1{ 2 "type": "module", 3 "source": "doc/api/assert.md", 4 "modules": [ 5 { 6 "textRaw": "Assert", 7 "name": "assert", 8 "introduced_in": "v0.1.21", 9 "stability": 2, 10 "stabilityText": "Stable", 11 "desc": "<p><strong>Source Code:</strong> <a href=\"https://github.com/nodejs/node/blob/v14.20.1/lib/assert.js\">lib/assert.js</a></p>\n<p>The <code>assert</code> module provides a set of assertion functions for verifying\ninvariants.</p>", 12 "modules": [ 13 { 14 "textRaw": "Strict assertion mode", 15 "name": "strict_assertion_mode", 16 "meta": { 17 "added": [ 18 "v9.9.0" 19 ], 20 "changes": [ 21 { 22 "version": [ 23 "v13.9.0", 24 "v12.16.2" 25 ], 26 "pr-url": "https://github.com/nodejs/node/pull/31635", 27 "description": "Changed \"strict mode\" to \"strict assertion mode\" and \"legacy mode\" to \"legacy assertion mode\" to avoid confusion with the more usual meaning of \"strict mode\"." 28 }, 29 { 30 "version": "v9.9.0", 31 "pr-url": "https://github.com/nodejs/node/pull/17615", 32 "description": "Added error diffs to the strict assertion mode." 33 }, 34 { 35 "version": "v9.9.0", 36 "pr-url": "https://github.com/nodejs/node/pull/17002", 37 "description": "Added strict assertion mode to the assert module." 38 } 39 ] 40 }, 41 "desc": "<p>In strict assertion mode, non-strict methods behave like their corresponding\nstrict methods. For example, <a href=\"#assert_assert_deepequal_actual_expected_message\"><code>assert.deepEqual()</code></a> will behave like\n<a href=\"#assert_assert_deepstrictequal_actual_expected_message\"><code>assert.deepStrictEqual()</code></a>.</p>\n<p>In strict assertion mode, error messages for objects display a diff. In legacy\nassertion mode, error messages for objects display the objects, often truncated.</p>\n<p>To use strict assertion mode:</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n</code></pre>\n<p>Example error diff:</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.deepEqual([[[1, 2, 3]], 4, 5], [[[1, 2, '3']], 4, 5]);\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected ... Lines skipped\n//\n// [\n// [\n// ...\n// 2,\n// + 3\n// - '3'\n// ],\n// ...\n// 5\n// ]\n</code></pre>\n<p>To deactivate the colors, use the <code>NO_COLOR</code> or <code>NODE_DISABLE_COLORS</code>\nenvironment variables. This will also deactivate the colors in the REPL. For\nmore on color support in terminal environments, read the tty\n<a href=\"tty.html#tty_writestream_getcolordepth_env\">getColorDepth()</a> documentation.</p>", 42 "type": "module", 43 "displayName": "Strict assertion mode" 44 }, 45 { 46 "textRaw": "Legacy assertion mode", 47 "name": "legacy_assertion_mode", 48 "desc": "<p>Legacy assertion mode uses the <a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a> in:</p>\n<ul>\n<li><a href=\"#assert_assert_deepequal_actual_expected_message\"><code>assert.deepEqual()</code></a></li>\n<li><a href=\"#assert_assert_equal_actual_expected_message\"><code>assert.equal()</code></a></li>\n<li><a href=\"#assert_assert_notdeepequal_actual_expected_message\"><code>assert.notDeepEqual()</code></a></li>\n<li><a href=\"#assert_assert_notequal_actual_expected_message\"><code>assert.notEqual()</code></a></li>\n</ul>\n<p>To use legacy assertion mode:</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n</code></pre>\n<p>Whenever possible, use the <a href=\"#assert_strict_assertion_mode\">strict assertion mode</a> instead. Otherwise, the\n<a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a> may cause surprising results. This is\nespecially true for <a href=\"#assert_assert_deepequal_actual_expected_message\"><code>assert.deepEqual()</code></a>, where the comparison rules are\nlax:</p>\n<pre><code class=\"language-js\">// WARNING: This does not throw an AssertionError!\nassert.deepEqual(/a/gi, new Date());\n</code></pre>", 49 "type": "module", 50 "displayName": "Legacy assertion mode" 51 } 52 ], 53 "classes": [ 54 { 55 "textRaw": "Class: assert.AssertionError", 56 "type": "class", 57 "name": "assert.AssertionError", 58 "desc": "<ul>\n<li>Extends: <a href=\"errors.html#errors_class_error\" class=\"type\"><errors.Error></a></li>\n</ul>\n<p>Indicates the failure of an assertion. All errors thrown by the <code>assert</code> module\nwill be instances of the <code>AssertionError</code> class.</p>", 59 "signatures": [ 60 { 61 "params": [ 62 { 63 "textRaw": "`options` {Object}", 64 "name": "options", 65 "type": "Object", 66 "options": [ 67 { 68 "textRaw": "`message` {string} If provided, the error message is set to this value.", 69 "name": "message", 70 "type": "string", 71 "desc": "If provided, the error message is set to this value." 72 }, 73 { 74 "textRaw": "`actual` {any} The `actual` property on the error instance.", 75 "name": "actual", 76 "type": "any", 77 "desc": "The `actual` property on the error instance." 78 }, 79 { 80 "textRaw": "`expected` {any} The `expected` property on the error instance.", 81 "name": "expected", 82 "type": "any", 83 "desc": "The `expected` property on the error instance." 84 }, 85 { 86 "textRaw": "`operator` {string} The `operator` property on the error instance.", 87 "name": "operator", 88 "type": "string", 89 "desc": "The `operator` property on the error instance." 90 }, 91 { 92 "textRaw": "`stackStartFn` {Function} If provided, the generated stack trace omits frames before this function.", 93 "name": "stackStartFn", 94 "type": "Function", 95 "desc": "If provided, the generated stack trace omits frames before this function." 96 } 97 ] 98 } 99 ], 100 "desc": "<p>A subclass of <code>Error</code> that indicates the failure of an assertion.</p>\n<p>All instances contain the built-in <code>Error</code> properties (<code>message</code> and <code>name</code>)\nand:</p>\n<ul>\n<li><code>actual</code> <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types\" class=\"type\"><any></a> Set to the <code>actual</code> argument for methods such as\n<a href=\"#assert_assert_strictequal_actual_expected_message\"><code>assert.strictEqual()</code></a>.</li>\n<li><code>expected</code> <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types\" class=\"type\"><any></a> Set to the <code>expected</code> value for methods such as\n<a href=\"#assert_assert_strictequal_actual_expected_message\"><code>assert.strictEqual()</code></a>.</li>\n<li><code>generatedMessage</code> <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type\" class=\"type\"><boolean></a> Indicates if the message was auto-generated\n(<code>true</code>) or not.</li>\n<li><code>code</code> <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type\" class=\"type\"><string></a> Value is always <code>ERR_ASSERTION</code> to show that the error is an\nassertion error.</li>\n<li><code>operator</code> <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type\" class=\"type\"><string></a> Set to the passed in operator value.</li>\n</ul>\n<pre><code class=\"language-js\">const assert = require('assert');\n\n// Generate an AssertionError to compare the error message later:\nconst { message } = new assert.AssertionError({\n actual: 1,\n expected: 2,\n operator: 'strictEqual'\n});\n\n// Verify error output:\ntry {\n assert.strictEqual(1, 2);\n} catch (err) {\n assert(err instanceof assert.AssertionError);\n assert.strictEqual(err.message, message);\n assert.strictEqual(err.name, 'AssertionError');\n assert.strictEqual(err.actual, 1);\n assert.strictEqual(err.expected, 2);\n assert.strictEqual(err.code, 'ERR_ASSERTION');\n assert.strictEqual(err.operator, 'strictEqual');\n assert.strictEqual(err.generatedMessage, true);\n}\n</code></pre>" 101 } 102 ] 103 }, 104 { 105 "textRaw": "Class: `assert.CallTracker`", 106 "type": "class", 107 "name": "assert.CallTracker", 108 "meta": { 109 "added": [ 110 "v14.2.0" 111 ], 112 "changes": [] 113 }, 114 "stability": 1, 115 "stabilityText": "Experimental", 116 "desc": "<p>This feature is currently experimental and behavior might still change.</p>", 117 "methods": [ 118 { 119 "textRaw": "`tracker.calls([fn][, exact])`", 120 "type": "method", 121 "name": "calls", 122 "meta": { 123 "added": [ 124 "v14.2.0" 125 ], 126 "changes": [] 127 }, 128 "signatures": [ 129 { 130 "return": { 131 "textRaw": "Returns: {Function} that wraps `fn`.", 132 "name": "return", 133 "type": "Function", 134 "desc": "that wraps `fn`." 135 }, 136 "params": [ 137 { 138 "textRaw": "`fn` {Function} **Default** A no-op function.", 139 "name": "fn", 140 "type": "Function", 141 "desc": "**Default** A no-op function." 142 }, 143 { 144 "textRaw": "`exact` {number} **Default** `1`.", 145 "name": "exact", 146 "type": "number", 147 "desc": "**Default** `1`." 148 } 149 ] 150 } 151 ], 152 "desc": "<p>The wrapper function is expected to be called exactly <code>exact</code> times. If the\nfunction has not been called exactly <code>exact</code> times when\n<a href=\"#assert_tracker_verify\"><code>tracker.verify()</code></a> is called, then <a href=\"#assert_tracker_verify\"><code>tracker.verify()</code></a> will throw an\nerror.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\n// Creates call tracker.\nconst tracker = new assert.CallTracker();\n\nfunction func() {}\n\n// Returns a function that wraps func() that must be called exact times\n// before tracker.verify().\nconst callsfunc = tracker.calls(func);\n</code></pre>" 153 }, 154 { 155 "textRaw": "`tracker.report()`", 156 "type": "method", 157 "name": "report", 158 "meta": { 159 "added": [ 160 "v14.2.0" 161 ], 162 "changes": [] 163 }, 164 "signatures": [ 165 { 166 "return": { 167 "textRaw": "Returns: {Array} of objects containing information about the wrapper functions returned by [`tracker.calls()`][].", 168 "name": "return", 169 "type": "Array", 170 "desc": "of objects containing information about the wrapper functions returned by [`tracker.calls()`][]." 171 }, 172 "params": [ 173 { 174 "textRaw": "Object {Object}", 175 "name": "Object", 176 "type": "Object", 177 "options": [ 178 { 179 "textRaw": "`message` {string}", 180 "name": "message", 181 "type": "string" 182 }, 183 { 184 "textRaw": "`actual` {number} The actual number of times the function was called.", 185 "name": "actual", 186 "type": "number", 187 "desc": "The actual number of times the function was called." 188 }, 189 { 190 "textRaw": "`expected` {number} The number of times the function was expected to be called.", 191 "name": "expected", 192 "type": "number", 193 "desc": "The number of times the function was expected to be called." 194 }, 195 { 196 "textRaw": "`operator` {string} The name of the function that is wrapped.", 197 "name": "operator", 198 "type": "string", 199 "desc": "The name of the function that is wrapped." 200 }, 201 { 202 "textRaw": "`stack` {Object} A stack trace of the function.", 203 "name": "stack", 204 "type": "Object", 205 "desc": "A stack trace of the function." 206 } 207 ] 208 } 209 ] 210 } 211 ], 212 "desc": "<p>The arrays contains information about the expected and actual number of calls of\nthe functions that have not been called the expected number of times.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\n// Creates call tracker.\nconst tracker = new assert.CallTracker();\n\nfunction func() {}\n\nfunction foo() {}\n\n// Returns a function that wraps func() that must be called exact times\n// before tracker.verify().\nconst callsfunc = tracker.calls(func, 2);\n\n// Returns an array containing information on callsfunc()\ntracker.report();\n// [\n// {\n// message: 'Expected the func function to be executed 2 time(s) but was\n// executed 0 time(s).',\n// actual: 0,\n// expected: 2,\n// operator: 'func',\n// stack: stack trace\n// }\n// ]\n</code></pre>" 213 }, 214 { 215 "textRaw": "`tracker.verify()`", 216 "type": "method", 217 "name": "verify", 218 "meta": { 219 "added": [ 220 "v14.2.0" 221 ], 222 "changes": [] 223 }, 224 "signatures": [ 225 { 226 "params": [] 227 } 228 ], 229 "desc": "<p>Iterates through the list of functions passed to\n<a href=\"#assert_tracker_calls_fn_exact\"><code>tracker.calls()</code></a> and will throw an error for functions that\nhave not been called the expected number of times.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\n// Creates call tracker.\nconst tracker = new assert.CallTracker();\n\nfunction func() {}\n\n// Returns a function that wraps func() that must be called exact times\n// before tracker.verify().\nconst callsfunc = tracker.calls(func, 2);\n\ncallsfunc();\n\n// Will throw an error since callsfunc() was only called once.\ntracker.verify();\n</code></pre>" 230 } 231 ], 232 "signatures": [ 233 { 234 "params": [], 235 "desc": "<p>Creates a new <a href=\"#assert_class_assert_calltracker\"><code>CallTracker</code></a> object which can be used to track if functions\nwere called a specific number of times. The <code>tracker.verify()</code> must be called\nfor the verification to take place. The usual pattern would be to call it in a\n<a href=\"process.html#process_event_exit\"><code>process.on('exit')</code></a> handler.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\nconst tracker = new assert.CallTracker();\n\nfunction func() {}\n\n// callsfunc() must be called exactly 1 time before tracker.verify().\nconst callsfunc = tracker.calls(func, 1);\n\ncallsfunc();\n\n// Calls tracker.verify() and verifies if all tracker.calls() functions have\n// been called exact times.\nprocess.on('exit', () => {\n tracker.verify();\n});\n</code></pre>" 236 } 237 ] 238 } 239 ], 240 "methods": [ 241 { 242 "textRaw": "`assert(value[, message])`", 243 "type": "method", 244 "name": "assert", 245 "meta": { 246 "added": [ 247 "v0.5.9" 248 ], 249 "changes": [] 250 }, 251 "signatures": [ 252 { 253 "params": [ 254 { 255 "textRaw": "`value` {any} The input that is checked for being truthy.", 256 "name": "value", 257 "type": "any", 258 "desc": "The input that is checked for being truthy." 259 }, 260 { 261 "textRaw": "`message` {string|Error}", 262 "name": "message", 263 "type": "string|Error" 264 } 265 ] 266 } 267 ], 268 "desc": "<p>An alias of <a href=\"#assert_assert_ok_value_message\"><code>assert.ok()</code></a>.</p>" 269 }, 270 { 271 "textRaw": "`assert.deepEqual(actual, expected[, message])`", 272 "type": "method", 273 "name": "deepEqual", 274 "meta": { 275 "added": [ 276 "v0.1.21" 277 ], 278 "changes": [ 279 { 280 "version": "v14.18.0", 281 "pr-url": "https://github.com/nodejs/node/pull/38113", 282 "description": "In Legacy assertion mode, changed status from Deprecated to Legacy." 283 }, 284 { 285 "version": "v14.0.0", 286 "pr-url": "https://github.com/nodejs/node/pull/30766", 287 "description": "NaN is now treated as being identical in case both sides are NaN." 288 }, 289 { 290 "version": "v12.0.0", 291 "pr-url": "https://github.com/nodejs/node/pull/25008", 292 "description": "The type tags are now properly compared and there are a couple minor comparison adjustments to make the check less surprising." 293 }, 294 { 295 "version": "v9.0.0", 296 "pr-url": "https://github.com/nodejs/node/pull/15001", 297 "description": "The `Error` names and messages are now properly compared." 298 }, 299 { 300 "version": "v8.0.0", 301 "pr-url": "https://github.com/nodejs/node/pull/12142", 302 "description": "The `Set` and `Map` content is also compared." 303 }, 304 { 305 "version": [ 306 "v6.4.0", 307 "v4.7.1" 308 ], 309 "pr-url": "https://github.com/nodejs/node/pull/8002", 310 "description": "Typed array slices are handled correctly now." 311 }, 312 { 313 "version": [ 314 "v6.1.0", 315 "v4.5.0" 316 ], 317 "pr-url": "https://github.com/nodejs/node/pull/6432", 318 "description": "Objects with circular references can be used as inputs now." 319 }, 320 { 321 "version": [ 322 "v5.10.1", 323 "v4.4.3" 324 ], 325 "pr-url": "https://github.com/nodejs/node/pull/5910", 326 "description": "Handle non-`Uint8Array` typed arrays correctly." 327 } 328 ] 329 }, 330 "signatures": [ 331 { 332 "params": [ 333 { 334 "textRaw": "`actual` {any}", 335 "name": "actual", 336 "type": "any" 337 }, 338 { 339 "textRaw": "`expected` {any}", 340 "name": "expected", 341 "type": "any" 342 }, 343 { 344 "textRaw": "`message` {string|Error}", 345 "name": "message", 346 "type": "string|Error" 347 } 348 ] 349 } 350 ], 351 "desc": "<p><strong>Strict assertion mode</strong></p>\n<p>An alias of <a href=\"#assert_assert_deepstrictequal_actual_expected_message\"><code>assert.deepStrictEqual()</code></a>.</p>\n<p><strong>Legacy assertion mode</strong></p>\n<blockquote>\n<p>Stability: 3 - Legacy: Use <a href=\"#assert_assert_deepstrictequal_actual_expected_message\"><code>assert.deepStrictEqual()</code></a> instead.</p>\n</blockquote>\n<p>Tests for deep equality between the <code>actual</code> and <code>expected</code> parameters. Consider\nusing <a href=\"#assert_assert_deepstrictequal_actual_expected_message\"><code>assert.deepStrictEqual()</code></a> instead. <a href=\"#assert_assert_deepequal_actual_expected_message\"><code>assert.deepEqual()</code></a> can have\nsurprising results.</p>\n<p><em>Deep equality</em> means that the enumerable \"own\" properties of child objects\nare also recursively evaluated by the following rules.</p>", 352 "modules": [ 353 { 354 "textRaw": "Comparison details", 355 "name": "comparison_details", 356 "desc": "<ul>\n<li>Primitive values are compared with the <a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a>\n( <code>==</code> ) with the exception of <code>NaN</code>. It is treated as being identical in case\nboth sides are <code>NaN</code>.</li>\n<li><a href=\"https://tc39.github.io/ecma262/#sec-object.prototype.tostring\">Type tags</a> of objects should be the same.</li>\n<li>Only <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties\">enumerable \"own\" properties</a> are considered.</li>\n<li><a href=\"errors.html#errors_class_error\"><code>Error</code></a> names and messages are always compared, even if these are not\nenumerable properties.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript\">Object wrappers</a> are compared both as objects and unwrapped values.</li>\n<li><code>Object</code> properties are compared unordered.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map\"><code>Map</code></a> keys and <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set\"><code>Set</code></a> items are compared unordered.</li>\n<li>Recursion stops when both sides differ or both sides encounter a circular\nreference.</li>\n<li>Implementation does not test the <a href=\"https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots\"><code>[[Prototype]]</code></a> of\nobjects.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol\"><code>Symbol</code></a> properties are not compared.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap\"><code>WeakMap</code></a> and <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet\"><code>WeakSet</code></a> comparison does not rely on their values.</li>\n</ul>\n<p>The following example does not throw an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> because the\nprimitives are considered equal by the <a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a>\n( <code>==</code> ).</p>\n<pre><code class=\"language-js\">// WARNING: This does not throw an AssertionError!\nassert.deepEqual('+00000000', false);\n</code></pre>\n<p>\"Deep\" equality means that the enumerable \"own\" properties of child objects\nare evaluated also:</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\nconst obj1 = {\n a: {\n b: 1\n }\n};\nconst obj2 = {\n a: {\n b: 2\n }\n};\nconst obj3 = {\n a: {\n b: 1\n }\n};\nconst obj4 = Object.create(obj1);\n\nassert.deepEqual(obj1, obj1);\n// OK\n\n// Values of b are different:\nassert.deepEqual(obj1, obj2);\n// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }\n\nassert.deepEqual(obj1, obj3);\n// OK\n\n// Prototypes are ignored:\nassert.deepEqual(obj1, obj4);\n// AssertionError: { a: { b: 1 } } deepEqual {}\n</code></pre>\n<p>If the values are not equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code>\nproperty set equal to the value of the <code>message</code> parameter. If the <code>message</code>\nparameter is undefined, a default error message is assigned. If the <code>message</code>\nparameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>", 357 "type": "module", 358 "displayName": "Comparison details" 359 } 360 ] 361 }, 362 { 363 "textRaw": "`assert.deepStrictEqual(actual, expected[, message])`", 364 "type": "method", 365 "name": "deepStrictEqual", 366 "meta": { 367 "added": [ 368 "v1.2.0" 369 ], 370 "changes": [ 371 { 372 "version": "v9.0.0", 373 "pr-url": "https://github.com/nodejs/node/pull/15169", 374 "description": "Enumerable symbol properties are now compared." 375 }, 376 { 377 "version": "v9.0.0", 378 "pr-url": "https://github.com/nodejs/node/pull/15036", 379 "description": "The `NaN` is now compared using the [SameValueZero](https://tc39.github.io/ecma262/#sec-samevaluezero) comparison." 380 }, 381 { 382 "version": "v8.5.0", 383 "pr-url": "https://github.com/nodejs/node/pull/15001", 384 "description": "The `Error` names and messages are now properly compared." 385 }, 386 { 387 "version": "v8.0.0", 388 "pr-url": "https://github.com/nodejs/node/pull/12142", 389 "description": "The `Set` and `Map` content is also compared." 390 }, 391 { 392 "version": [ 393 "v6.4.0", 394 "v4.7.1" 395 ], 396 "pr-url": "https://github.com/nodejs/node/pull/8002", 397 "description": "Typed array slices are handled correctly now." 398 }, 399 { 400 "version": "v6.1.0", 401 "pr-url": "https://github.com/nodejs/node/pull/6432", 402 "description": "Objects with circular references can be used as inputs now." 403 }, 404 { 405 "version": [ 406 "v5.10.1", 407 "v4.4.3" 408 ], 409 "pr-url": "https://github.com/nodejs/node/pull/5910", 410 "description": "Handle non-`Uint8Array` typed arrays correctly." 411 } 412 ] 413 }, 414 "signatures": [ 415 { 416 "params": [ 417 { 418 "textRaw": "`actual` {any}", 419 "name": "actual", 420 "type": "any" 421 }, 422 { 423 "textRaw": "`expected` {any}", 424 "name": "expected", 425 "type": "any" 426 }, 427 { 428 "textRaw": "`message` {string|Error}", 429 "name": "message", 430 "type": "string|Error" 431 } 432 ] 433 } 434 ], 435 "desc": "<p>Tests for deep equality between the <code>actual</code> and <code>expected</code> parameters.\n\"Deep\" equality means that the enumerable \"own\" properties of child objects\nare recursively evaluated also by the following rules.</p>", 436 "modules": [ 437 { 438 "textRaw": "Comparison details", 439 "name": "comparison_details", 440 "desc": "<ul>\n<li>Primitive values are compared using the <a href=\"https://tc39.github.io/ecma262/#sec-samevalue\">SameValue Comparison</a>, used by\n<a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is\"><code>Object.is()</code></a>.</li>\n<li><a href=\"https://tc39.github.io/ecma262/#sec-object.prototype.tostring\">Type tags</a> of objects should be the same.</li>\n<li><a href=\"https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots\"><code>[[Prototype]]</code></a> of objects are compared using\nthe <a href=\"https://tc39.github.io/ecma262/#sec-strict-equality-comparison\">Strict Equality Comparison</a>.</li>\n<li>Only <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties\">enumerable \"own\" properties</a> are considered.</li>\n<li><a href=\"errors.html#errors_class_error\"><code>Error</code></a> names and messages are always compared, even if these are not\nenumerable properties.</li>\n<li>Enumerable own <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol\"><code>Symbol</code></a> properties are compared as well.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript\">Object wrappers</a> are compared both as objects and unwrapped values.</li>\n<li><code>Object</code> properties are compared unordered.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map\"><code>Map</code></a> keys and <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set\"><code>Set</code></a> items are compared unordered.</li>\n<li>Recursion stops when both sides differ or both sides encounter a circular\nreference.</li>\n<li><a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap\"><code>WeakMap</code></a> and <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet\"><code>WeakSet</code></a> comparison does not rely on their values. See\nbelow for further details.</li>\n</ul>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\n// This fails because 1 !== '1'.\nassert.deepStrictEqual({ a: 1 }, { a: '1' });\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// {\n// + a: 1\n// - a: '1'\n// }\n\n// The following objects don't have own properties\nconst date = new Date();\nconst object = {};\nconst fakeDate = {};\nObject.setPrototypeOf(fakeDate, Date.prototype);\n\n// Different [[Prototype]]:\nassert.deepStrictEqual(object, fakeDate);\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// + {}\n// - Date {}\n\n// Different type tags:\nassert.deepStrictEqual(date, fakeDate);\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// + 2018-04-26T00:49:08.604Z\n// - Date {}\n\nassert.deepStrictEqual(NaN, NaN);\n// OK, because of the SameValue comparison\n\n// Different unwrapped numbers:\nassert.deepStrictEqual(new Number(1), new Number(2));\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// + [Number: 1]\n// - [Number: 2]\n\nassert.deepStrictEqual(new String('foo'), Object('foo'));\n// OK because the object and the string are identical when unwrapped.\n\nassert.deepStrictEqual(-0, -0);\n// OK\n\n// Different zeros using the SameValue Comparison:\nassert.deepStrictEqual(0, -0);\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// + 0\n// - -0\n\nconst symbol1 = Symbol();\nconst symbol2 = Symbol();\nassert.deepStrictEqual({ [symbol1]: 1 }, { [symbol1]: 1 });\n// OK, because it is the same symbol on both objects.\n\nassert.deepStrictEqual({ [symbol1]: 1 }, { [symbol2]: 1 });\n// AssertionError [ERR_ASSERTION]: Inputs identical but not reference equal:\n//\n// {\n// [Symbol()]: 1\n// }\n\nconst weakMap1 = new WeakMap();\nconst weakMap2 = new WeakMap([[{}, {}]]);\nconst weakMap3 = new WeakMap();\nweakMap3.unequal = true;\n\nassert.deepStrictEqual(weakMap1, weakMap2);\n// OK, because it is impossible to compare the entries\n\n// Fails because weakMap3 has a property that weakMap1 does not contain:\nassert.deepStrictEqual(weakMap1, weakMap3);\n// AssertionError: Expected inputs to be strictly deep-equal:\n// + actual - expected\n//\n// WeakMap {\n// + [items unknown]\n// - [items unknown],\n// - unequal: true\n// }\n</code></pre>\n<p>If the values are not equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code>\nproperty set equal to the value of the <code>message</code> parameter. If the <code>message</code>\nparameter is undefined, a default error message is assigned. If the <code>message</code>\nparameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<code>AssertionError</code>.</p>", 441 "type": "module", 442 "displayName": "Comparison details" 443 } 444 ] 445 }, 446 { 447 "textRaw": "`assert.doesNotMatch(string, regexp[, message])`", 448 "type": "method", 449 "name": "doesNotMatch", 450 "meta": { 451 "added": [ 452 "v13.6.0", 453 "v12.16.0" 454 ], 455 "changes": [] 456 }, 457 "stability": 1, 458 "stabilityText": "Experimental", 459 "signatures": [ 460 { 461 "params": [ 462 { 463 "textRaw": "`string` {string}", 464 "name": "string", 465 "type": "string" 466 }, 467 { 468 "textRaw": "`regexp` {RegExp}", 469 "name": "regexp", 470 "type": "RegExp" 471 }, 472 { 473 "textRaw": "`message` {string|Error}", 474 "name": "message", 475 "type": "string|Error" 476 } 477 ] 478 } 479 ], 480 "desc": "<p>Expects the <code>string</code> input not to match the regular expression.</p>\n<p>This feature is currently experimental and the name might change or it might be\ncompletely removed again.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.doesNotMatch('I will fail', /fail/);\n// AssertionError [ERR_ASSERTION]: The input was expected to not match the ...\n\nassert.doesNotMatch(123, /pass/);\n// AssertionError [ERR_ASSERTION]: The \"string\" argument must be of type string.\n\nassert.doesNotMatch('I will pass', /different/);\n// OK\n</code></pre>\n<p>If the values do match, or if the <code>string</code> argument is of another type than\n<code>string</code>, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code> property set equal\nto the value of the <code>message</code> parameter. If the <code>message</code> parameter is\nundefined, a default error message is assigned. If the <code>message</code> parameter is an\ninstance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>" 481 }, 482 { 483 "textRaw": "`assert.doesNotReject(asyncFn[, error][, message])`", 484 "type": "method", 485 "name": "doesNotReject", 486 "meta": { 487 "added": [ 488 "v10.0.0" 489 ], 490 "changes": [] 491 }, 492 "signatures": [ 493 { 494 "params": [ 495 { 496 "textRaw": "`asyncFn` {Function|Promise}", 497 "name": "asyncFn", 498 "type": "Function|Promise" 499 }, 500 { 501 "textRaw": "`error` {RegExp|Function}", 502 "name": "error", 503 "type": "RegExp|Function" 504 }, 505 { 506 "textRaw": "`message` {string}", 507 "name": "message", 508 "type": "string" 509 } 510 ] 511 } 512 ], 513 "desc": "<p>Awaits the <code>asyncFn</code> promise or, if <code>asyncFn</code> is a function, immediately\ncalls the function and awaits the returned promise to complete. It will then\ncheck that the promise is not rejected.</p>\n<p>If <code>asyncFn</code> is a function and it throws an error synchronously,\n<code>assert.doesNotReject()</code> will return a rejected <code>Promise</code> with that error. If\nthe function does not return a promise, <code>assert.doesNotReject()</code> will return a\nrejected <code>Promise</code> with an <a href=\"errors.html#errors_err_invalid_return_value\"><code>ERR_INVALID_RETURN_VALUE</code></a> error. In both cases\nthe error handler is skipped.</p>\n<p>Using <code>assert.doesNotReject()</code> is actually not useful because there is little\nbenefit in catching a rejection and then rejecting it again. Instead, consider\nadding a comment next to the specific code path that should not reject and keep\nerror messages as expressive as possible.</p>\n<p>If specified, <code>error</code> can be a <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes\"><code>Class</code></a>, <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions\"><code>RegExp</code></a> or a validation\nfunction. See <a href=\"#assert_assert_throws_fn_error_message\"><code>assert.throws()</code></a> for more details.</p>\n<p>Besides the async nature to await the completion behaves identically to\n<a href=\"#assert_assert_doesnotthrow_fn_error_message\"><code>assert.doesNotThrow()</code></a>.</p>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">(async () => {\n await assert.doesNotReject(\n async () => {\n throw new TypeError('Wrong value');\n },\n SyntaxError\n );\n})();\n</code></pre>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">assert.doesNotReject(Promise.reject(new TypeError('Wrong value')))\n .then(() => {\n // ...\n });\n</code></pre>" 514 }, 515 { 516 "textRaw": "`assert.doesNotThrow(fn[, error][, message])`", 517 "type": "method", 518 "name": "doesNotThrow", 519 "meta": { 520 "added": [ 521 "v0.1.21" 522 ], 523 "changes": [ 524 { 525 "version": [ 526 "v5.11.0", 527 "v4.4.5" 528 ], 529 "pr-url": "https://github.com/nodejs/node/pull/2407", 530 "description": "The `message` parameter is respected now." 531 }, 532 { 533 "version": "v4.2.0", 534 "pr-url": "https://github.com/nodejs/node/pull/3276", 535 "description": "The `error` parameter can now be an arrow function." 536 } 537 ] 538 }, 539 "signatures": [ 540 { 541 "params": [ 542 { 543 "textRaw": "`fn` {Function}", 544 "name": "fn", 545 "type": "Function" 546 }, 547 { 548 "textRaw": "`error` {RegExp|Function}", 549 "name": "error", 550 "type": "RegExp|Function" 551 }, 552 { 553 "textRaw": "`message` {string}", 554 "name": "message", 555 "type": "string" 556 } 557 ] 558 } 559 ], 560 "desc": "<p>Asserts that the function <code>fn</code> does not throw an error.</p>\n<p>Using <code>assert.doesNotThrow()</code> is actually not useful because there\nis no benefit in catching an error and then rethrowing it. Instead, consider\nadding a comment next to the specific code path that should not throw and keep\nerror messages as expressive as possible.</p>\n<p>When <code>assert.doesNotThrow()</code> is called, it will immediately call the <code>fn</code>\nfunction.</p>\n<p>If an error is thrown and it is the same type as that specified by the <code>error</code>\nparameter, then an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown. If the error is of a\ndifferent type, or if the <code>error</code> parameter is undefined, the error is\npropagated back to the caller.</p>\n<p>If specified, <code>error</code> can be a <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes\"><code>Class</code></a>, <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions\"><code>RegExp</code></a> or a validation\nfunction. See <a href=\"#assert_assert_throws_fn_error_message\"><code>assert.throws()</code></a> for more details.</p>\n<p>The following, for instance, will throw the <a href=\"errors.html#errors_class_typeerror\"><code>TypeError</code></a> because there is no\nmatching error type in the assertion:</p>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">assert.doesNotThrow(\n () => {\n throw new TypeError('Wrong value');\n },\n SyntaxError\n);\n</code></pre>\n<p>However, the following will result in an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> with the message\n'Got unwanted exception...':</p>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">assert.doesNotThrow(\n () => {\n throw new TypeError('Wrong value');\n },\n TypeError\n);\n</code></pre>\n<p>If an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown and a value is provided for the <code>message</code>\nparameter, the value of <code>message</code> will be appended to the <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>\nmessage:</p>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">assert.doesNotThrow(\n () => {\n throw new TypeError('Wrong value');\n },\n /Wrong value/,\n 'Whoops'\n);\n// Throws: AssertionError: Got unwanted exception: Whoops\n</code></pre>" 561 }, 562 { 563 "textRaw": "`assert.equal(actual, expected[, message])`", 564 "type": "method", 565 "name": "equal", 566 "meta": { 567 "added": [ 568 "v0.1.21" 569 ], 570 "changes": [ 571 { 572 "version": "v14.18.0", 573 "pr-url": "https://github.com/nodejs/node/pull/38113", 574 "description": "In Legacy assertion mode, changed status from Deprecated to Legacy." 575 }, 576 { 577 "version": "v14.0.0", 578 "pr-url": "https://github.com/nodejs/node/pull/30766", 579 "description": "NaN is now treated as being identical in case both sides are NaN." 580 } 581 ] 582 }, 583 "signatures": [ 584 { 585 "params": [ 586 { 587 "textRaw": "`actual` {any}", 588 "name": "actual", 589 "type": "any" 590 }, 591 { 592 "textRaw": "`expected` {any}", 593 "name": "expected", 594 "type": "any" 595 }, 596 { 597 "textRaw": "`message` {string|Error}", 598 "name": "message", 599 "type": "string|Error" 600 } 601 ] 602 } 603 ], 604 "desc": "<p><strong>Strict assertion mode</strong></p>\n<p>An alias of <a href=\"#assert_assert_strictequal_actual_expected_message\"><code>assert.strictEqual()</code></a>.</p>\n<p><strong>Legacy assertion mode</strong></p>\n<blockquote>\n<p>Stability: 3 - Legacy: Use <a href=\"#assert_assert_strictequal_actual_expected_message\"><code>assert.strictEqual()</code></a> instead.</p>\n</blockquote>\n<p>Tests shallow, coercive equality between the <code>actual</code> and <code>expected</code> parameters\nusing the <a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a> ( <code>==</code> ). <code>NaN</code> is special handled\nand treated as being identical in case both sides are <code>NaN</code>.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\nassert.equal(1, 1);\n// OK, 1 == 1\nassert.equal(1, '1');\n// OK, 1 == '1'\nassert.equal(NaN, NaN);\n// OK\n\nassert.equal(1, 2);\n// AssertionError: 1 == 2\nassert.equal({ a: { b: 1 } }, { a: { b: 1 } });\n// AssertionError: { a: { b: 1 } } == { a: { b: 1 } }\n</code></pre>\n<p>If the values are not equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code>\nproperty set equal to the value of the <code>message</code> parameter. If the <code>message</code>\nparameter is undefined, a default error message is assigned. If the <code>message</code>\nparameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<code>AssertionError</code>.</p>" 605 }, 606 { 607 "textRaw": "`assert.fail([message])`", 608 "type": "method", 609 "name": "fail", 610 "meta": { 611 "added": [ 612 "v0.1.21" 613 ], 614 "changes": [] 615 }, 616 "signatures": [ 617 { 618 "params": [ 619 { 620 "textRaw": "`message` {string|Error} **Default:** `'Failed'`", 621 "name": "message", 622 "type": "string|Error", 623 "default": "`'Failed'`" 624 } 625 ] 626 } 627 ], 628 "desc": "<p>Throws an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> with the provided error message or a default\nerror message. If the <code>message</code> parameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then\nit will be thrown instead of the <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.fail();\n// AssertionError [ERR_ASSERTION]: Failed\n\nassert.fail('boom');\n// AssertionError [ERR_ASSERTION]: boom\n\nassert.fail(new TypeError('need array'));\n// TypeError: need array\n</code></pre>\n<p>Using <code>assert.fail()</code> with more than two arguments is possible but deprecated.\nSee below for further details.</p>" 629 }, 630 { 631 "textRaw": "`assert.fail(actual, expected[, message[, operator[, stackStartFn]]])`", 632 "type": "method", 633 "name": "fail", 634 "meta": { 635 "added": [ 636 "v0.1.21" 637 ], 638 "changes": [ 639 { 640 "version": "v10.0.0", 641 "pr-url": "https://github.com/nodejs/node/pull/18418", 642 "description": "Calling `assert.fail()` with more than one argument is deprecated and emits a warning." 643 } 644 ] 645 }, 646 "stability": 0, 647 "stabilityText": "Deprecated: Use `assert.fail([message])` or other assert\nfunctions instead.", 648 "signatures": [ 649 { 650 "params": [ 651 { 652 "textRaw": "`actual` {any}", 653 "name": "actual", 654 "type": "any" 655 }, 656 { 657 "textRaw": "`expected` {any}", 658 "name": "expected", 659 "type": "any" 660 }, 661 { 662 "textRaw": "`message` {string|Error}", 663 "name": "message", 664 "type": "string|Error" 665 }, 666 { 667 "textRaw": "`operator` {string} **Default:** `'!='`", 668 "name": "operator", 669 "type": "string", 670 "default": "`'!='`" 671 }, 672 { 673 "textRaw": "`stackStartFn` {Function} **Default:** `assert.fail`", 674 "name": "stackStartFn", 675 "type": "Function", 676 "default": "`assert.fail`" 677 } 678 ] 679 } 680 ], 681 "desc": "<p>If <code>message</code> is falsy, the error message is set as the values of <code>actual</code> and\n<code>expected</code> separated by the provided <code>operator</code>. If just the two <code>actual</code> and\n<code>expected</code> arguments are provided, <code>operator</code> will default to <code>'!='</code>. If\n<code>message</code> is provided as third argument it will be used as the error message and\nthe other arguments will be stored as properties on the thrown object. If\n<code>stackStartFn</code> is provided, all stack frames above that function will be\nremoved from stacktrace (see <a href=\"errors.html#errors_error_capturestacktrace_targetobject_constructoropt\"><code>Error.captureStackTrace</code></a>). If no arguments are\ngiven, the default message <code>Failed</code> will be used.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.fail('a', 'b');\n// AssertionError [ERR_ASSERTION]: 'a' != 'b'\n\nassert.fail(1, 2, undefined, '>');\n// AssertionError [ERR_ASSERTION]: 1 > 2\n\nassert.fail(1, 2, 'fail');\n// AssertionError [ERR_ASSERTION]: fail\n\nassert.fail(1, 2, 'whoops', '>');\n// AssertionError [ERR_ASSERTION]: whoops\n\nassert.fail(1, 2, new TypeError('need array'));\n// TypeError: need array\n</code></pre>\n<p>In the last three cases <code>actual</code>, <code>expected</code>, and <code>operator</code> have no\ninfluence on the error message.</p>\n<p>Example use of <code>stackStartFn</code> for truncating the exception's stacktrace:</p>\n<pre><code class=\"language-js\">function suppressFrame() {\n assert.fail('a', 'b', undefined, '!==', suppressFrame);\n}\nsuppressFrame();\n// AssertionError [ERR_ASSERTION]: 'a' !== 'b'\n// at repl:1:1\n// at ContextifyScript.Script.runInThisContext (vm.js:44:33)\n// ...\n</code></pre>" 682 }, 683 { 684 "textRaw": "`assert.ifError(value)`", 685 "type": "method", 686 "name": "ifError", 687 "meta": { 688 "added": [ 689 "v0.1.97" 690 ], 691 "changes": [ 692 { 693 "version": "v10.0.0", 694 "pr-url": "https://github.com/nodejs/node/pull/18247", 695 "description": "Instead of throwing the original error it is now wrapped into an [`AssertionError`][] that contains the full stack trace." 696 }, 697 { 698 "version": "v10.0.0", 699 "pr-url": "https://github.com/nodejs/node/pull/18247", 700 "description": "Value may now only be `undefined` or `null`. Before all falsy values were handled the same as `null` and did not throw." 701 } 702 ] 703 }, 704 "signatures": [ 705 { 706 "params": [ 707 { 708 "textRaw": "`value` {any}", 709 "name": "value", 710 "type": "any" 711 } 712 ] 713 } 714 ], 715 "desc": "<p>Throws <code>value</code> if <code>value</code> is not <code>undefined</code> or <code>null</code>. This is useful when\ntesting the <code>error</code> argument in callbacks. The stack trace contains all frames\nfrom the error passed to <code>ifError()</code> including the potential new frames for\n<code>ifError()</code> itself.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.ifError(null);\n// OK\nassert.ifError(0);\n// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 0\nassert.ifError('error');\n// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 'error'\nassert.ifError(new Error());\n// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: Error\n\n// Create some random error frames.\nlet err;\n(function errorFrame() {\n err = new Error('test error');\n})();\n\n(function ifErrorFrame() {\n assert.ifError(err);\n})();\n// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: test error\n// at ifErrorFrame\n// at errorFrame\n</code></pre>" 716 }, 717 { 718 "textRaw": "`assert.match(string, regexp[, message])`", 719 "type": "method", 720 "name": "match", 721 "meta": { 722 "added": [ 723 "v13.6.0", 724 "v12.16.0" 725 ], 726 "changes": [] 727 }, 728 "stability": 1, 729 "stabilityText": "Experimental", 730 "signatures": [ 731 { 732 "params": [ 733 { 734 "textRaw": "`string` {string}", 735 "name": "string", 736 "type": "string" 737 }, 738 { 739 "textRaw": "`regexp` {RegExp}", 740 "name": "regexp", 741 "type": "RegExp" 742 }, 743 { 744 "textRaw": "`message` {string|Error}", 745 "name": "message", 746 "type": "string|Error" 747 } 748 ] 749 } 750 ], 751 "desc": "<p>Expects the <code>string</code> input to match the regular expression.</p>\n<p>This feature is currently experimental and the name might change or it might be\ncompletely removed again.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.match('I will fail', /pass/);\n// AssertionError [ERR_ASSERTION]: The input did not match the regular ...\n\nassert.match(123, /pass/);\n// AssertionError [ERR_ASSERTION]: The \"string\" argument must be of type string.\n\nassert.match('I will pass', /pass/);\n// OK\n</code></pre>\n<p>If the values do not match, or if the <code>string</code> argument is of another type than\n<code>string</code>, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code> property set equal\nto the value of the <code>message</code> parameter. If the <code>message</code> parameter is\nundefined, a default error message is assigned. If the <code>message</code> parameter is an\ninstance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>" 752 }, 753 { 754 "textRaw": "`assert.notDeepEqual(actual, expected[, message])`", 755 "type": "method", 756 "name": "notDeepEqual", 757 "meta": { 758 "added": [ 759 "v0.1.21" 760 ], 761 "changes": [ 762 { 763 "version": "v14.18.0", 764 "pr-url": "https://github.com/nodejs/node/pull/38113", 765 "description": "In Legacy assertion mode, changed status from Deprecated to Legacy." 766 }, 767 { 768 "version": "v14.0.0", 769 "pr-url": "https://github.com/nodejs/node/pull/30766", 770 "description": "NaN is now treated as being identical in case both sides are NaN." 771 }, 772 { 773 "version": "v9.0.0", 774 "pr-url": "https://github.com/nodejs/node/pull/15001", 775 "description": "The `Error` names and messages are now properly compared." 776 }, 777 { 778 "version": "v8.0.0", 779 "pr-url": "https://github.com/nodejs/node/pull/12142", 780 "description": "The `Set` and `Map` content is also compared." 781 }, 782 { 783 "version": [ 784 "v6.4.0", 785 "v4.7.1" 786 ], 787 "pr-url": "https://github.com/nodejs/node/pull/8002", 788 "description": "Typed array slices are handled correctly now." 789 }, 790 { 791 "version": [ 792 "v6.1.0", 793 "v4.5.0" 794 ], 795 "pr-url": "https://github.com/nodejs/node/pull/6432", 796 "description": "Objects with circular references can be used as inputs now." 797 }, 798 { 799 "version": [ 800 "v5.10.1", 801 "v4.4.3" 802 ], 803 "pr-url": "https://github.com/nodejs/node/pull/5910", 804 "description": "Handle non-`Uint8Array` typed arrays correctly." 805 } 806 ] 807 }, 808 "signatures": [ 809 { 810 "params": [ 811 { 812 "textRaw": "`actual` {any}", 813 "name": "actual", 814 "type": "any" 815 }, 816 { 817 "textRaw": "`expected` {any}", 818 "name": "expected", 819 "type": "any" 820 }, 821 { 822 "textRaw": "`message` {string|Error}", 823 "name": "message", 824 "type": "string|Error" 825 } 826 ] 827 } 828 ], 829 "desc": "<p><strong>Strict assertion mode</strong></p>\n<p>An alias of <a href=\"#assert_assert_notdeepstrictequal_actual_expected_message\"><code>assert.notDeepStrictEqual()</code></a>.</p>\n<p><strong>Legacy assertion mode</strong></p>\n<blockquote>\n<p>Stability: 3 - Legacy: Use <a href=\"#assert_assert_notdeepstrictequal_actual_expected_message\"><code>assert.notDeepStrictEqual()</code></a> instead.</p>\n</blockquote>\n<p>Tests for any deep inequality. Opposite of <a href=\"#assert_assert_deepequal_actual_expected_message\"><code>assert.deepEqual()</code></a>.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\nconst obj1 = {\n a: {\n b: 1\n }\n};\nconst obj2 = {\n a: {\n b: 2\n }\n};\nconst obj3 = {\n a: {\n b: 1\n }\n};\nconst obj4 = Object.create(obj1);\n\nassert.notDeepEqual(obj1, obj1);\n// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }\n\nassert.notDeepEqual(obj1, obj2);\n// OK\n\nassert.notDeepEqual(obj1, obj3);\n// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }\n\nassert.notDeepEqual(obj1, obj4);\n// OK\n</code></pre>\n<p>If the values are deeply equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a\n<code>message</code> property set equal to the value of the <code>message</code> parameter. If the\n<code>message</code> parameter is undefined, a default error message is assigned. If the\n<code>message</code> parameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown\ninstead of the <code>AssertionError</code>.</p>" 830 }, 831 { 832 "textRaw": "`assert.notDeepStrictEqual(actual, expected[, message])`", 833 "type": "method", 834 "name": "notDeepStrictEqual", 835 "meta": { 836 "added": [ 837 "v1.2.0" 838 ], 839 "changes": [ 840 { 841 "version": "v9.0.0", 842 "pr-url": "https://github.com/nodejs/node/pull/15398", 843 "description": "The `-0` and `+0` are not considered equal anymore." 844 }, 845 { 846 "version": "v9.0.0", 847 "pr-url": "https://github.com/nodejs/node/pull/15036", 848 "description": "The `NaN` is now compared using the [SameValueZero](https://tc39.github.io/ecma262/#sec-samevaluezero) comparison." 849 }, 850 { 851 "version": "v9.0.0", 852 "pr-url": "https://github.com/nodejs/node/pull/15001", 853 "description": "The `Error` names and messages are now properly compared." 854 }, 855 { 856 "version": "v8.0.0", 857 "pr-url": "https://github.com/nodejs/node/pull/12142", 858 "description": "The `Set` and `Map` content is also compared." 859 }, 860 { 861 "version": [ 862 "v6.4.0", 863 "v4.7.1" 864 ], 865 "pr-url": "https://github.com/nodejs/node/pull/8002", 866 "description": "Typed array slices are handled correctly now." 867 }, 868 { 869 "version": "v6.1.0", 870 "pr-url": "https://github.com/nodejs/node/pull/6432", 871 "description": "Objects with circular references can be used as inputs now." 872 }, 873 { 874 "version": [ 875 "v5.10.1", 876 "v4.4.3" 877 ], 878 "pr-url": "https://github.com/nodejs/node/pull/5910", 879 "description": "Handle non-`Uint8Array` typed arrays correctly." 880 } 881 ] 882 }, 883 "signatures": [ 884 { 885 "params": [ 886 { 887 "textRaw": "`actual` {any}", 888 "name": "actual", 889 "type": "any" 890 }, 891 { 892 "textRaw": "`expected` {any}", 893 "name": "expected", 894 "type": "any" 895 }, 896 { 897 "textRaw": "`message` {string|Error}", 898 "name": "message", 899 "type": "string|Error" 900 } 901 ] 902 } 903 ], 904 "desc": "<p>Tests for deep strict inequality. Opposite of <a href=\"#assert_assert_deepstrictequal_actual_expected_message\"><code>assert.deepStrictEqual()</code></a>.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.notDeepStrictEqual({ a: 1 }, { a: '1' });\n// OK\n</code></pre>\n<p>If the values are deeply and strictly equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown\nwith a <code>message</code> property set equal to the value of the <code>message</code> parameter. If\nthe <code>message</code> parameter is undefined, a default error message is assigned. If\nthe <code>message</code> parameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown\ninstead of the <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>" 905 }, 906 { 907 "textRaw": "`assert.notEqual(actual, expected[, message])`", 908 "type": "method", 909 "name": "notEqual", 910 "meta": { 911 "added": [ 912 "v0.1.21" 913 ], 914 "changes": [ 915 { 916 "version": "v14.18.0", 917 "pr-url": "https://github.com/nodejs/node/pull/38113", 918 "description": "In Legacy assertion mode, changed status from Deprecated to Legacy." 919 }, 920 { 921 "version": "v14.0.0", 922 "pr-url": "https://github.com/nodejs/node/pull/30766", 923 "description": "NaN is now treated as being identical in case both sides are NaN." 924 } 925 ] 926 }, 927 "signatures": [ 928 { 929 "params": [ 930 { 931 "textRaw": "`actual` {any}", 932 "name": "actual", 933 "type": "any" 934 }, 935 { 936 "textRaw": "`expected` {any}", 937 "name": "expected", 938 "type": "any" 939 }, 940 { 941 "textRaw": "`message` {string|Error}", 942 "name": "message", 943 "type": "string|Error" 944 } 945 ] 946 } 947 ], 948 "desc": "<p><strong>Strict assertion mode</strong></p>\n<p>An alias of <a href=\"#assert_assert_notstrictequal_actual_expected_message\"><code>assert.notStrictEqual()</code></a>.</p>\n<p><strong>Legacy assertion mode</strong></p>\n<blockquote>\n<p>Stability: 3 - Legacy: Use <a href=\"#assert_assert_notstrictequal_actual_expected_message\"><code>assert.notStrictEqual()</code></a> instead.</p>\n</blockquote>\n<p>Tests shallow, coercive inequality with the <a href=\"https://tc39.github.io/ecma262/#sec-abstract-equality-comparison\">Abstract Equality Comparison</a>\n(<code>!=</code> ). <code>NaN</code> is special handled and treated as being identical in case both\nsides are <code>NaN</code>.</p>\n<pre><code class=\"language-js\">const assert = require('assert');\n\nassert.notEqual(1, 2);\n// OK\n\nassert.notEqual(1, 1);\n// AssertionError: 1 != 1\n\nassert.notEqual(1, '1');\n// AssertionError: 1 != '1'\n</code></pre>\n<p>If the values are equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code>\nproperty set equal to the value of the <code>message</code> parameter. If the <code>message</code>\nparameter is undefined, a default error message is assigned. If the <code>message</code>\nparameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<code>AssertionError</code>.</p>" 949 }, 950 { 951 "textRaw": "`assert.notStrictEqual(actual, expected[, message])`", 952 "type": "method", 953 "name": "notStrictEqual", 954 "meta": { 955 "added": [ 956 "v0.1.21" 957 ], 958 "changes": [ 959 { 960 "version": "v10.0.0", 961 "pr-url": "https://github.com/nodejs/node/pull/17003", 962 "description": "Used comparison changed from Strict Equality to `Object.is()`." 963 } 964 ] 965 }, 966 "signatures": [ 967 { 968 "params": [ 969 { 970 "textRaw": "`actual` {any}", 971 "name": "actual", 972 "type": "any" 973 }, 974 { 975 "textRaw": "`expected` {any}", 976 "name": "expected", 977 "type": "any" 978 }, 979 { 980 "textRaw": "`message` {string|Error}", 981 "name": "message", 982 "type": "string|Error" 983 } 984 ] 985 } 986 ], 987 "desc": "<p>Tests strict inequality between the <code>actual</code> and <code>expected</code> parameters as\ndetermined by the <a href=\"https://tc39.github.io/ecma262/#sec-samevalue\">SameValue Comparison</a>.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.notStrictEqual(1, 2);\n// OK\n\nassert.notStrictEqual(1, 1);\n// AssertionError [ERR_ASSERTION]: Expected \"actual\" to be strictly unequal to:\n//\n// 1\n\nassert.notStrictEqual(1, '1');\n// OK\n</code></pre>\n<p>If the values are strictly equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a\n<code>message</code> property set equal to the value of the <code>message</code> parameter. If the\n<code>message</code> parameter is undefined, a default error message is assigned. If the\n<code>message</code> parameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown\ninstead of the <code>AssertionError</code>.</p>" 988 }, 989 { 990 "textRaw": "`assert.ok(value[, message])`", 991 "type": "method", 992 "name": "ok", 993 "meta": { 994 "added": [ 995 "v0.1.21" 996 ], 997 "changes": [ 998 { 999 "version": "v10.0.0", 1000 "pr-url": "https://github.com/nodejs/node/pull/18319", 1001 "description": "The `assert.ok()` (no arguments) will now use a predefined error message." 1002 } 1003 ] 1004 }, 1005 "signatures": [ 1006 { 1007 "params": [ 1008 { 1009 "textRaw": "`value` {any}", 1010 "name": "value", 1011 "type": "any" 1012 }, 1013 { 1014 "textRaw": "`message` {string|Error}", 1015 "name": "message", 1016 "type": "string|Error" 1017 } 1018 ] 1019 } 1020 ], 1021 "desc": "<p>Tests if <code>value</code> is truthy. It is equivalent to\n<code>assert.equal(!!value, true, message)</code>.</p>\n<p>If <code>value</code> is not truthy, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a <code>message</code>\nproperty set equal to the value of the <code>message</code> parameter. If the <code>message</code>\nparameter is <code>undefined</code>, a default error message is assigned. If the <code>message</code>\nparameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown instead of the\n<code>AssertionError</code>.\nIf no arguments are passed in at all <code>message</code> will be set to the string:\n<code>'No value argument passed to `assert.ok()`'</code>.</p>\n<p>Be aware that in the <code>repl</code> the error message will be different to the one\nthrown in a file! See below for further details.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.ok(true);\n// OK\nassert.ok(1);\n// OK\n\nassert.ok();\n// AssertionError: No value argument passed to `assert.ok()`\n\nassert.ok(false, 'it\\'s false');\n// AssertionError: it's false\n\n// In the repl:\nassert.ok(typeof 123 === 'string');\n// AssertionError: false == true\n\n// In a file (e.g. test.js):\nassert.ok(typeof 123 === 'string');\n// AssertionError: The expression evaluated to a falsy value:\n//\n// assert.ok(typeof 123 === 'string')\n\nassert.ok(false);\n// AssertionError: The expression evaluated to a falsy value:\n//\n// assert.ok(false)\n\nassert.ok(0);\n// AssertionError: The expression evaluated to a falsy value:\n//\n// assert.ok(0)\n\n// Using `assert()` works the same:\nassert(0);\n// AssertionError: The expression evaluated to a falsy value:\n//\n// assert(0)\n</code></pre>" 1022 }, 1023 { 1024 "textRaw": "`assert.rejects(asyncFn[, error][, message])`", 1025 "type": "method", 1026 "name": "rejects", 1027 "meta": { 1028 "added": [ 1029 "v10.0.0" 1030 ], 1031 "changes": [] 1032 }, 1033 "signatures": [ 1034 { 1035 "params": [ 1036 { 1037 "textRaw": "`asyncFn` {Function|Promise}", 1038 "name": "asyncFn", 1039 "type": "Function|Promise" 1040 }, 1041 { 1042 "textRaw": "`error` {RegExp|Function|Object|Error}", 1043 "name": "error", 1044 "type": "RegExp|Function|Object|Error" 1045 }, 1046 { 1047 "textRaw": "`message` {string}", 1048 "name": "message", 1049 "type": "string" 1050 } 1051 ] 1052 } 1053 ], 1054 "desc": "<p>Awaits the <code>asyncFn</code> promise or, if <code>asyncFn</code> is a function, immediately\ncalls the function and awaits the returned promise to complete. It will then\ncheck that the promise is rejected.</p>\n<p>If <code>asyncFn</code> is a function and it throws an error synchronously,\n<code>assert.rejects()</code> will return a rejected <code>Promise</code> with that error. If the\nfunction does not return a promise, <code>assert.rejects()</code> will return a rejected\n<code>Promise</code> with an <a href=\"errors.html#errors_err_invalid_return_value\"><code>ERR_INVALID_RETURN_VALUE</code></a> error. In both cases the error\nhandler is skipped.</p>\n<p>Besides the async nature to await the completion behaves identically to\n<a href=\"#assert_assert_throws_fn_error_message\"><code>assert.throws()</code></a>.</p>\n<p>If specified, <code>error</code> can be a <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes\"><code>Class</code></a>, <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions\"><code>RegExp</code></a>, a validation function,\nan object where each property will be tested for, or an instance of error where\neach property will be tested for including the non-enumerable <code>message</code> and\n<code>name</code> properties.</p>\n<p>If specified, <code>message</code> will be the message provided by the <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>\nif the <code>asyncFn</code> fails to reject.</p>\n<pre><code class=\"language-js\">(async () => {\n await assert.rejects(\n async () => {\n throw new TypeError('Wrong value');\n },\n {\n name: 'TypeError',\n message: 'Wrong value'\n }\n );\n})();\n</code></pre>\n<pre><code class=\"language-js\">(async () => {\n await assert.rejects(\n async () => {\n throw new TypeError('Wrong value');\n },\n (err) => {\n assert.strictEqual(err.name, 'TypeError');\n assert.strictEqual(err.message, 'Wrong value');\n return true;\n }\n );\n})();\n</code></pre>\n<pre><code class=\"language-js\">assert.rejects(\n Promise.reject(new Error('Wrong value')),\n Error\n).then(() => {\n // ...\n});\n</code></pre>\n<p><code>error</code> cannot be a string. If a string is provided as the second\nargument, then <code>error</code> is assumed to be omitted and the string will be used for\n<code>message</code> instead. This can lead to easy-to-miss mistakes. Please read the\nexample in <a href=\"#assert_assert_throws_fn_error_message\"><code>assert.throws()</code></a> carefully if using a string as the second\nargument gets considered.</p>" 1055 }, 1056 { 1057 "textRaw": "`assert.strictEqual(actual, expected[, message])`", 1058 "type": "method", 1059 "name": "strictEqual", 1060 "meta": { 1061 "added": [ 1062 "v0.1.21" 1063 ], 1064 "changes": [ 1065 { 1066 "version": "v10.0.0", 1067 "pr-url": "https://github.com/nodejs/node/pull/17003", 1068 "description": "Used comparison changed from Strict Equality to `Object.is()`." 1069 } 1070 ] 1071 }, 1072 "signatures": [ 1073 { 1074 "params": [ 1075 { 1076 "textRaw": "`actual` {any}", 1077 "name": "actual", 1078 "type": "any" 1079 }, 1080 { 1081 "textRaw": "`expected` {any}", 1082 "name": "expected", 1083 "type": "any" 1084 }, 1085 { 1086 "textRaw": "`message` {string|Error}", 1087 "name": "message", 1088 "type": "string|Error" 1089 } 1090 ] 1091 } 1092 ], 1093 "desc": "<p>Tests strict equality between the <code>actual</code> and <code>expected</code> parameters as\ndetermined by the <a href=\"https://tc39.github.io/ecma262/#sec-samevalue\">SameValue Comparison</a>.</p>\n<pre><code class=\"language-js\">const assert = require('assert').strict;\n\nassert.strictEqual(1, 2);\n// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:\n//\n// 1 !== 2\n\nassert.strictEqual(1, 1);\n// OK\n\nassert.strictEqual('Hello foobar', 'Hello World!');\n// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:\n// + actual - expected\n//\n// + 'Hello foobar'\n// - 'Hello World!'\n// ^\n\nconst apples = 1;\nconst oranges = 2;\nassert.strictEqual(apples, oranges, `apples ${apples} !== oranges ${oranges}`);\n// AssertionError [ERR_ASSERTION]: apples 1 !== oranges 2\n\nassert.strictEqual(1, '1', new TypeError('Inputs are not identical'));\n// TypeError: Inputs are not identical\n</code></pre>\n<p>If the values are not strictly equal, an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a> is thrown with a\n<code>message</code> property set equal to the value of the <code>message</code> parameter. If the\n<code>message</code> parameter is undefined, a default error message is assigned. If the\n<code>message</code> parameter is an instance of an <a href=\"errors.html#errors_class_error\"><code>Error</code></a> then it will be thrown\ninstead of the <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>" 1094 }, 1095 { 1096 "textRaw": "`assert.throws(fn[, error][, message])`", 1097 "type": "method", 1098 "name": "throws", 1099 "meta": { 1100 "added": [ 1101 "v0.1.21" 1102 ], 1103 "changes": [ 1104 { 1105 "version": "v10.2.0", 1106 "pr-url": "https://github.com/nodejs/node/pull/20485", 1107 "description": "The `error` parameter can be an object containing regular expressions now." 1108 }, 1109 { 1110 "version": "v9.9.0", 1111 "pr-url": "https://github.com/nodejs/node/pull/17584", 1112 "description": "The `error` parameter can now be an object as well." 1113 }, 1114 { 1115 "version": "v4.2.0", 1116 "pr-url": "https://github.com/nodejs/node/pull/3276", 1117 "description": "The `error` parameter can now be an arrow function." 1118 } 1119 ] 1120 }, 1121 "signatures": [ 1122 { 1123 "params": [ 1124 { 1125 "textRaw": "`fn` {Function}", 1126 "name": "fn", 1127 "type": "Function" 1128 }, 1129 { 1130 "textRaw": "`error` {RegExp|Function|Object|Error}", 1131 "name": "error", 1132 "type": "RegExp|Function|Object|Error" 1133 }, 1134 { 1135 "textRaw": "`message` {string}", 1136 "name": "message", 1137 "type": "string" 1138 } 1139 ] 1140 } 1141 ], 1142 "desc": "<p>Expects the function <code>fn</code> to throw an error.</p>\n<p>If specified, <code>error</code> can be a <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes\"><code>Class</code></a>, <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions\"><code>RegExp</code></a>, a validation function,\na validation object where each property will be tested for strict deep equality,\nor an instance of error where each property will be tested for strict deep\nequality including the non-enumerable <code>message</code> and <code>name</code> properties. When\nusing an object, it is also possible to use a regular expression, when\nvalidating against a string property. See below for examples.</p>\n<p>If specified, <code>message</code> will be appended to the message provided by the\n<code>AssertionError</code> if the <code>fn</code> call fails to throw or in case the error validation\nfails.</p>\n<p>Custom validation object/error instance:</p>\n<pre><code class=\"language-js\">const err = new TypeError('Wrong value');\nerr.code = 404;\nerr.foo = 'bar';\nerr.info = {\n nested: true,\n baz: 'text'\n};\nerr.reg = /abc/i;\n\nassert.throws(\n () => {\n throw err;\n },\n {\n name: 'TypeError',\n message: 'Wrong value',\n info: {\n nested: true,\n baz: 'text'\n }\n // Only properties on the validation object will be tested for.\n // Using nested objects requires all properties to be present. Otherwise\n // the validation is going to fail.\n }\n);\n\n// Using regular expressions to validate error properties:\nassert.throws(\n () => {\n throw err;\n },\n {\n // The `name` and `message` properties are strings and using regular\n // expressions on those will match against the string. If they fail, an\n // error is thrown.\n name: /^TypeError$/,\n message: /Wrong/,\n foo: 'bar',\n info: {\n nested: true,\n // It is not possible to use regular expressions for nested properties!\n baz: 'text'\n },\n // The `reg` property contains a regular expression and only if the\n // validation object contains an identical regular expression, it is going\n // to pass.\n reg: /abc/i\n }\n);\n\n// Fails due to the different `message` and `name` properties:\nassert.throws(\n () => {\n const otherErr = new Error('Not found');\n // Copy all enumerable properties from `err` to `otherErr`.\n for (const [key, value] of Object.entries(err)) {\n otherErr[key] = value;\n }\n throw otherErr;\n },\n // The error's `message` and `name` properties will also be checked when using\n // an error as validation object.\n err\n);\n</code></pre>\n<p>Validate instanceof using constructor:</p>\n<pre><code class=\"language-js\">assert.throws(\n () => {\n throw new Error('Wrong value');\n },\n Error\n);\n</code></pre>\n<p>Validate error message using <a href=\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions\"><code>RegExp</code></a>:</p>\n<p>Using a regular expression runs <code>.toString</code> on the error object, and will\ntherefore also include the error name.</p>\n<pre><code class=\"language-js\">assert.throws(\n () => {\n throw new Error('Wrong value');\n },\n /^Error: Wrong value$/\n);\n</code></pre>\n<p>Custom error validation:</p>\n<p>The function must return <code>true</code> to indicate all internal validations passed.\nIt will otherwise fail with an <a href=\"#assert_class_assert_assertionerror\"><code>AssertionError</code></a>.</p>\n<pre><code class=\"language-js\">assert.throws(\n () => {\n throw new Error('Wrong value');\n },\n (err) => {\n assert(err instanceof Error);\n assert(/value/.test(err));\n // Avoid returning anything from validation functions besides `true`.\n // Otherwise, it's not clear what part of the validation failed. Instead,\n // throw an error about the specific validation that failed (as done in this\n // example) and add as much helpful debugging information to that error as\n // possible.\n return true;\n },\n 'unexpected error'\n);\n</code></pre>\n<p><code>error</code> cannot be a string. If a string is provided as the second\nargument, then <code>error</code> is assumed to be omitted and the string will be used for\n<code>message</code> instead. This can lead to easy-to-miss mistakes. Using the same\nmessage as the thrown error message is going to result in an\n<code>ERR_AMBIGUOUS_ARGUMENT</code> error. Please read the example below carefully if using\na string as the second argument gets considered:</p>\n<!-- eslint-disable no-restricted-syntax -->\n<pre><code class=\"language-js\">function throwingFirst() {\n throw new Error('First');\n}\n\nfunction throwingSecond() {\n throw new Error('Second');\n}\n\nfunction notThrowing() {}\n\n// The second argument is a string and the input function threw an Error.\n// The first case will not throw as it does not match for the error message\n// thrown by the input function!\nassert.throws(throwingFirst, 'Second');\n// In the next example the message has no benefit over the message from the\n// error and since it is not clear if the user intended to actually match\n// against the error message, Node.js throws an `ERR_AMBIGUOUS_ARGUMENT` error.\nassert.throws(throwingSecond, 'Second');\n// TypeError [ERR_AMBIGUOUS_ARGUMENT]\n\n// The string is only used (as message) in case the function does not throw:\nassert.throws(notThrowing, 'Second');\n// AssertionError [ERR_ASSERTION]: Missing expected exception: Second\n\n// If it was intended to match for the error message do this instead:\n// It does not throw because the error messages match.\nassert.throws(throwingSecond, /Second$/);\n\n// If the error message does not match, an AssertionError is thrown.\nassert.throws(throwingFirst, /Second$/);\n// AssertionError [ERR_ASSERTION]\n</code></pre>\n<p>Due to the confusing error-prone notation, avoid a string as the second\nargument.</p>" 1143 } 1144 ], 1145 "type": "module", 1146 "displayName": "Assert" 1147 } 1148 ] 1149}