Lib/test/test_tabnanny.py

"""Testing `tabnanny` module.

Glossary:
    * errored    : Whitespace related problems present in file.
"""
from unittest import TestCase, mock
import errno
import os
import tabnanny
import tokenize
import tempfile
import textwrap
from test.support import (captured_stderr, captured_stdout, script_helper,
                          findfile)
from test.support.os_helper import unlink


SOURCE_CODES = {
    "incomplete_expression": (
        'fruits = [\n'
        '    "Apple",\n'
        '    "Orange",\n'
        '    "Banana",\n'
        '\n'
        'print(fruits)\n'
    ),
    "wrong_indented": (
        'if True:\n'
        '    print("hello")\n'
        '  print("world")\n'
        'else:\n'
        '    print("else called")\n'
    ),
    "nannynag_errored": (
        'if True:\n'
        ' \tprint("hello")\n'
        '\tprint("world")\n'
        'else:\n'
        '    print("else called")\n'
    ),
    "error_free": (
        'if True:\n'
        '    print("hello")\n'
        '    print("world")\n'
        'else:\n'
        '    print("else called")\n'
    ),
    "tab_space_errored_1": (
        'def my_func():\n'
        '\t  print("hello world")\n'
        '\t  if True:\n'
        '\t\tprint("If called")'
    ),
    "tab_space_errored_2": (
        'def my_func():\n'
        '\t\tprint("Hello world")\n'
        '\t\tif True:\n'
        '\t        print("If called")'
    )
}


class TemporaryPyFile:
    """Create a temporary python source code file."""

    def __init__(self, source_code='', directory=None):
        self.source_code = source_code
        self.dir = directory

    def __enter__(self):
        with tempfile.NamedTemporaryFile(
            mode='w', dir=self.dir, suffix=".py", delete=False
        ) as f:
            f.write(self.source_code)
        self.file_path = f.name
        return self.file_path

    def __exit__(self, exc_type, exc_value, exc_traceback):
        unlink(self.file_path)


class TestFormatWitnesses(TestCase):
    """Testing `tabnanny.format_witnesses()`."""

    def test_format_witnesses(self):
        """Asserting formatter result by giving various input samples."""
        tests = [
            ('Test', 'at tab sizes T, e, s, t'),
            ('', 'at tab size '),
            ('t', 'at tab size t'),
            ('  t  ', 'at tab sizes  ,  , t,  ,  '),
        ]

        for words, expected in tests:
            with self.subTest(words=words, expected=expected):
                self.assertEqual(tabnanny.format_witnesses(words), expected)


class TestErrPrint(TestCase):
    """Testing `tabnanny.errprint()`."""

    def test_errprint(self):
        """Asserting result of `tabnanny.errprint()` by giving sample inputs."""
        tests = [
            (['first', 'second'], 'first second\n'),
            (['first'], 'first\n'),
            ([1, 2, 3], '1 2 3\n'),
            ([], '\n')
        ]

        for args, expected in tests:
            with self.subTest(arguments=args, expected=expected):
                with self.assertRaises(SystemExit):
                    with captured_stderr() as stderr:
                        tabnanny.errprint(*args)
                    self.assertEqual(stderr.getvalue() , expected)


class TestNannyNag(TestCase):
    def test_all_methods(self):
        """Asserting behaviour of `tabnanny.NannyNag` exception."""
        tests = [
            (
                tabnanny.NannyNag(0, "foo", "bar"),
                {'lineno': 0, 'msg': 'foo', 'line': 'bar'}
            ),
            (
                tabnanny.NannyNag(5, "testmsg", "testline"),
                {'lineno': 5, 'msg': 'testmsg', 'line': 'testline'}
            )
        ]
        for nanny, expected in tests:
            line_number = nanny.get_lineno()
            msg = nanny.get_msg()
            line = nanny.get_line()
            with self.subTest(
                line_number=line_number, expected=expected['lineno']
            ):
                self.assertEqual(expected['lineno'], line_number)
            with self.subTest(msg=msg, expected=expected['msg']):
                self.assertEqual(expected['msg'], msg)
            with self.subTest(line=line, expected=expected['line']):
                self.assertEqual(expected['line'], line)


class TestCheck(TestCase):
    """Testing tabnanny.check()."""

    def setUp(self):
        self.addCleanup(setattr, tabnanny, 'verbose', tabnanny.verbose)
        tabnanny.verbose = 0  # Forcefully deactivating verbose mode.

    def verify_tabnanny_check(self, dir_or_file, out="", err=""):
        """Common verification for tabnanny.check().

        Use this method to assert expected values of `stdout` and `stderr` after
        running tabnanny.check() on given `dir` or `file` path. Because
        tabnanny.check() captures exceptions and writes to `stdout` and
        `stderr`, asserting standard outputs is the only way.
        """
        with captured_stdout() as stdout, captured_stderr() as stderr:
            tabnanny.check(dir_or_file)
        self.assertEqual(stdout.getvalue(), out)
        self.assertEqual(stderr.getvalue(), err)

    def test_correct_file(self):
        """A python source code file without any errors."""
        with TemporaryPyFile(SOURCE_CODES["error_free"]) as file_path:
            self.verify_tabnanny_check(file_path)

    def test_correct_directory_verbose(self):
        """Directory containing few error free python source code files.

        Because order of files returned by `os.lsdir()` is not fixed, verify the
        existence of each output lines at `stdout` using `in` operator.
        `verbose` mode of `tabnanny.verbose` asserts `stdout`.
        """
        with tempfile.TemporaryDirectory() as tmp_dir:
            lines = [f"{tmp_dir!r}: listing directory\n",]
            file1 = TemporaryPyFile(SOURCE_CODES["error_free"], directory=tmp_dir)
            file2 = TemporaryPyFile(SOURCE_CODES["error_free"], directory=tmp_dir)
            with file1 as file1_path, file2 as file2_path:
                for file_path in (file1_path, file2_path):
                    lines.append(f"{file_path!r}: Clean bill of health.\n")

                tabnanny.verbose = 1
                with captured_stdout() as stdout, captured_stderr() as stderr:
                    tabnanny.check(tmp_dir)
                stdout = stdout.getvalue()
                for line in lines:
                    with self.subTest(line=line):
                        self.assertIn(line, stdout)
                self.assertEqual(stderr.getvalue(), "")

    def test_correct_directory(self):
        """Directory which contains few error free python source code files."""
        with tempfile.TemporaryDirectory() as tmp_dir:
            with TemporaryPyFile(SOURCE_CODES["error_free"], directory=tmp_dir):
                self.verify_tabnanny_check(tmp_dir)

    def test_when_wrong_indented(self):
        """A python source code file eligible for raising `IndentationError`."""
        with TemporaryPyFile(SOURCE_CODES["wrong_indented"]) as file_path:
            err = ('unindent does not match any outer indentation level'
                ' (<tokenize>, line 3)\n')
            err = f"{file_path!r}: Indentation Error: {err}"
            with self.assertRaises(SystemExit):
                self.verify_tabnanny_check(file_path, err=err)

    def test_when_tokenize_tokenerror(self):
        """A python source code file eligible for raising 'tokenize.TokenError'."""
        with TemporaryPyFile(SOURCE_CODES["incomplete_expression"]) as file_path:
            err = "('EOF in multi-line statement', (7, 0))\n"
            err = f"{file_path!r}: Token Error: {err}"
            with self.assertRaises(SystemExit):
                self.verify_tabnanny_check(file_path, err=err)

    def test_when_nannynag_error_verbose(self):
        """A python source code file eligible for raising `tabnanny.NannyNag`.

        Tests will assert `stdout` after activating `tabnanny.verbose` mode.
        """
        with TemporaryPyFile(SOURCE_CODES["nannynag_errored"]) as file_path:
            out = f"{file_path!r}: *** Line 3: trouble in tab city! ***\n"
            out += "offending line: '\\tprint(\"world\")'\n"
            out += "inconsistent use of tabs and spaces in indentation\n"

            tabnanny.verbose = 1
            self.verify_tabnanny_check(file_path, out=out)

    def test_when_nannynag_error(self):
        """A python source code file eligible for raising `tabnanny.NannyNag`."""
        with TemporaryPyFile(SOURCE_CODES["nannynag_errored"]) as file_path:
            out = f"{file_path} 3 '\\tprint(\"world\")'\n"
            self.verify_tabnanny_check(file_path, out=out)

    def test_when_no_file(self):
        """A python file which does not exist actually in system."""
        path = 'no_file.py'
        err = (f"{path!r}: I/O Error: [Errno {errno.ENOENT}] "
              f"{os.strerror(errno.ENOENT)}: {path!r}\n")
        with self.assertRaises(SystemExit):
            self.verify_tabnanny_check(path, err=err)

    def test_errored_directory(self):
        """Directory containing wrongly indented python source code files."""
        with tempfile.TemporaryDirectory() as tmp_dir:
            error_file = TemporaryPyFile(
                SOURCE_CODES["wrong_indented"], directory=tmp_dir
            )
            code_file = TemporaryPyFile(
                SOURCE_CODES["error_free"], directory=tmp_dir
            )
            with error_file as e_file, code_file as c_file:
                err = ('unindent does not match any outer indentation level'
                            ' (<tokenize>, line 3)\n')
                err = f"{e_file!r}: Indentation Error: {err}"
                with self.assertRaises(SystemExit):
                    self.verify_tabnanny_check(tmp_dir, err=err)


class TestProcessTokens(TestCase):
    """Testing `tabnanny.process_tokens()`."""

    @mock.patch('tabnanny.NannyNag')
    def test_with_correct_code(self, MockNannyNag):
        """A python source code without any whitespace related problems."""

        with TemporaryPyFile(SOURCE_CODES["error_free"]) as file_path:
            with open(file_path) as f:
                tabnanny.process_tokens(tokenize.generate_tokens(f.readline))
            self.assertFalse(MockNannyNag.called)

    def test_with_errored_codes_samples(self):
        """A python source code with whitespace related sampled problems."""

        # "tab_space_errored_1": executes block under type == tokenize.INDENT
        #                        at `tabnanny.process_tokens()`.
        # "tab space_errored_2": executes block under
        #                        `check_equal and type not in JUNK` condition at
        #                        `tabnanny.process_tokens()`.

        for key in ["tab_space_errored_1", "tab_space_errored_2"]:
            with self.subTest(key=key):
                with TemporaryPyFile(SOURCE_CODES[key]) as file_path:
                    with open(file_path) as f:
                        tokens = tokenize.generate_tokens(f.readline)
                        with self.assertRaises(tabnanny.NannyNag):
                            tabnanny.process_tokens(tokens)


class TestCommandLine(TestCase):
    """Tests command line interface of `tabnanny`."""

    def validate_cmd(self, *args, stdout="", stderr="", partial=False, expect_failure=False):
        """Common function to assert the behaviour of command line interface."""
        if expect_failure:
            _, out, err = script_helper.assert_python_failure('-m', 'tabnanny', *args)
        else:
            _, out, err = script_helper.assert_python_ok('-m', 'tabnanny', *args)
        # Note: The `splitlines()` will solve the problem of CRLF(\r) added
        # by OS Windows.
        out = os.fsdecode(out)
        err = os.fsdecode(err)
        if partial:
            for std, output in ((stdout, out), (stderr, err)):
                _output = output.splitlines()
                for _std in std.splitlines():
                    with self.subTest(std=_std, output=_output):
                        self.assertIn(_std, _output)
        else:
            self.assertListEqual(out.splitlines(), stdout.splitlines())
            self.assertListEqual(err.splitlines(), stderr.splitlines())

    def test_with_errored_file(self):
        """Should displays error when errored python file is given."""
        with TemporaryPyFile(SOURCE_CODES["wrong_indented"]) as file_path:
            stderr  = f"{file_path!r}: Indentation Error: "
            stderr += ('unindent does not match any outer indentation level'
                       ' (<string>, line 3)')
            self.validate_cmd(file_path, stderr=stderr, expect_failure=True)

    def test_with_error_free_file(self):
        """Should not display anything if python file is correctly indented."""
        with TemporaryPyFile(SOURCE_CODES["error_free"]) as file_path:
            self.validate_cmd(file_path)

    def test_command_usage(self):
        """Should display usage on no arguments."""
        path = findfile('tabnanny.py')
        stderr = f"Usage: {path} [-v] file_or_directory ..."
        self.validate_cmd(stderr=stderr, expect_failure=True)

    def test_quiet_flag(self):
        """Should display less when quite mode is on."""
        with TemporaryPyFile(SOURCE_CODES["nannynag_errored"]) as file_path:
            stdout = f"{file_path}\n"
            self.validate_cmd("-q", file_path, stdout=stdout)

    def test_verbose_mode(self):
        """Should display more error information if verbose mode is on."""
        with TemporaryPyFile(SOURCE_CODES["nannynag_errored"]) as path:
            stdout = textwrap.dedent(
                "offending line: '\\tprint(\"world\")'"
            ).strip()
            self.validate_cmd("-v", path, stdout=stdout, partial=True)

    def test_double_verbose_mode(self):
        """Should display detailed error information if double verbose is on."""
        with TemporaryPyFile(SOURCE_CODES["nannynag_errored"]) as path:
            stdout = textwrap.dedent(
                "offending line: '\\tprint(\"world\")'"
            ).strip()
            self.validate_cmd("-vv", path, stdout=stdout, partial=True)