1<a id="top"></a> 2# Logging macros 3 4Additional messages can be logged during a test case. Note that the messages logged with `INFO` are scoped and thus will not be reported if failure occurs in scope preceding the message declaration. An example: 5 6```cpp 7TEST_CASE("Foo") { 8 INFO("Test case start"); 9 for (int i = 0; i < 2; ++i) { 10 INFO("The number is " << i); 11 CHECK(i == 0); 12 } 13} 14 15TEST_CASE("Bar") { 16 INFO("Test case start"); 17 for (int i = 0; i < 2; ++i) { 18 INFO("The number is " << i); 19 CHECK(i == i); 20 } 21 CHECK(false); 22} 23``` 24When the `CHECK` fails in the "Foo" test case, then two messages will be printed. 25``` 26Test case start 27The number is 1 28``` 29When the last `CHECK` fails in the "Bar" test case, then only one message will be printed: `Test case start`. 30 31## Logging without local scope 32 33`UNSCOPED_INFO` is similar to `INFO` with two key differences: 34 35- Lifetime of an unscoped message is not tied to its own scope. 36- An unscoped message can be reported by the first following assertion only, regardless of the result of that assertion. 37 38In other words, lifetime of `UNSCOPED_INFO` is limited by the following assertion (or by the end of test case/section, whichever comes first) whereas lifetime of `INFO` is limited by its own scope. 39 40These differences make this macro useful for reporting information from helper functions or inner scopes. An example: 41 42```cpp 43void print_some_info() { 44 UNSCOPED_INFO("Info from helper"); 45} 46 47TEST_CASE("Baz") { 48 print_some_info(); 49 for (int i = 0; i < 2; ++i) { 50 UNSCOPED_INFO("The number is " << i); 51 } 52 CHECK(false); 53} 54 55TEST_CASE("Qux") { 56 INFO("First info"); 57 UNSCOPED_INFO("First unscoped info"); 58 CHECK(false); 59 60 INFO("Second info"); 61 UNSCOPED_INFO("Second unscoped info"); 62 CHECK(false); 63} 64``` 65 66"Baz" test case prints: 67``` 68Info from helper 69The number is 0 70The number is 1 71``` 72 73With "Qux" test case, two messages will be printed when the first `CHECK` fails: 74``` 75First info 76First unscoped info 77``` 78 79"First unscoped info" message will be cleared after the first `CHECK`, while "First info" message will persist until the end of the test case. Therefore, when the second `CHECK` fails, three messages will be printed: 80``` 81First info 82Second info 83Second unscoped info 84``` 85 86## Streaming macros 87 88All these macros allow heterogeneous sequences of values to be streaming using the insertion operator (```<<```) in the same way that std::ostream, std::cout, etc support it. 89 90E.g.: 91```c++ 92INFO( "The number is " << i ); 93``` 94 95(Note that there is no initial ```<<``` - instead the insertion sequence is placed in parentheses.) 96These macros come in three forms: 97 98**INFO(** _message expression_ **)** 99 100The message is logged to a buffer, but only reported with next assertions that are logged. This allows you to log contextual information in case of failures which is not shown during a successful test run (for the console reporter, without -s). Messages are removed from the buffer at the end of their scope, so may be used, for example, in loops. 101 102_Note that in Catch2 2.x.x `INFO` can be used without a trailing semicolon as there is a trailing semicolon inside macro. 103This semicolon will be removed with next major version. It is highly advised to use a trailing semicolon after `INFO` macro._ 104 105**UNSCOPED_INFO(** _message expression_ **)** 106 107Similar to `INFO`, but messages are not limited to their own scope: They are removed from the buffer after each assertion, section or test case, whichever comes first. 108 109**WARN(** _message expression_ **)** 110 111The message is always reported but does not fail the test. 112 113**FAIL(** _message expression_ **)** 114 115The message is reported and the test case fails. 116 117**FAIL_CHECK(** _message expression_ **)** 118 119AS `FAIL`, but does not abort the test 120 121## Quickly capture value of variables or expressions 122 123**CAPTURE(** _expression1_, _expression2_, ... **)** 124 125Sometimes you just want to log a value of variable, or expression. For 126convenience, we provide the `CAPTURE` macro, that can take a variable, 127or an expression, and prints out that variable/expression and its value 128at the time of capture. 129 130e.g. `CAPTURE( theAnswer );` will log message "theAnswer := 42", while 131```cpp 132int a = 1, b = 2, c = 3; 133CAPTURE( a, b, c, a + b, c > b, a == 1); 134``` 135will log a total of 6 messages: 136``` 137a := 1 138b := 2 139c := 3 140a + b := 3 141c > b := true 142a == 1 := true 143``` 144 145You can also capture expressions that use commas inside parentheses 146(e.g. function calls), brackets, or braces (e.g. initializers). To 147properly capture expression that contains template parameters list 148(in other words, it contains commas between angle brackets), you need 149to enclose the expression inside parentheses: 150`CAPTURE( (std::pair<int, int>{1, 2}) );` 151 152 153--- 154 155[Home](Readme.md#top) 156