src/third_party/WebKit/Tools/Scripts/webkitpy/common/system/outputcapture.py

   1 # Copyright (c) 2009, Google Inc. All rights reserved.
   2 #
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   4 # modification, are permitted provided that the following conditions are
   5 # met:
   6 #
   7 #     * Redistributions of source code must retain the above copyright
   8 # notice, this list of conditions and the following disclaimer.
   9 #     * Redistributions in binary form must reproduce the above
  10 # copyright notice, this list of conditions and the following disclaimer
  11 # in the documentation and/or other materials provided with the
  12 # distribution.
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  14 # contributors may be used to endorse or promote products derived from
  15 # this software without specific prior written permission.
  16 #
  17 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28 #
  29 # Class for unittest support.  Used for capturing stderr/stdout.
  30
  31 import logging
  32 import sys
  33 import unittest
  34
  35 from StringIO import StringIO
  36
  37
  38 class OutputCapture(object):
  39
  40     def __init__(self):
  41         self.saved_outputs = dict()
  42         self._log_level = logging.INFO
  43
  44     def set_log_level(self, log_level):
  45         self._log_level = log_level
  46         if hasattr(self, '_logs_handler'):
  47             self._logs_handler.setLevel(self._log_level)
  48
  49     def _capture_output_with_name(self, output_name):
  50         stream = getattr(sys, output_name)
  51         captured_output = StringIO()
  52         self.saved_outputs[output_name] = stream
  53         setattr(sys, output_name, captured_output)
  54         return captured_output
  55
  56     def _restore_output_with_name(self, output_name):
  57         captured_output = getattr(sys, output_name).getvalue()
  58         setattr(sys, output_name, self.saved_outputs[output_name])
  59         del self.saved_outputs[output_name]
  60         return captured_output
  61
  62     def capture_output(self):
  63         self._logs = StringIO()
  64         self._logs_handler = logging.StreamHandler(self._logs)
  65         self._logs_handler.setLevel(self._log_level)
  66         self._logger = logging.getLogger()
  67         self._orig_log_level = self._logger.level
  68         self._logger.addHandler(self._logs_handler)
  69         self._logger.setLevel(min(self._log_level, self._orig_log_level))
  70         return (self._capture_output_with_name("stdout"), self._capture_output_with_name("stderr"))
  71
  72     def restore_output(self):
  73         self._logger.removeHandler(self._logs_handler)
  74         self._logger.setLevel(self._orig_log_level)
  75         self._logs_handler.flush()
  76         self._logs.flush()
  77         logs_string = self._logs.getvalue()
  78         delattr(self, '_logs_handler')
  79         delattr(self, '_logs')
  80         return (self._restore_output_with_name("stdout"), self._restore_output_with_name("stderr"), logs_string)
  81
  82     def assert_outputs(self, testcase, function, args=[], kwargs={}, expected_stdout="", expected_stderr="", expected_exception=None, expected_logs=None):
  83         self.capture_output()
  84         try:
  85             if expected_exception:
  86                 return_value = testcase.assertRaises(expected_exception, function, *args, **kwargs)
  87             else:
  88                 return_value = function(*args, **kwargs)
  89         finally:
  90             (stdout_string, stderr_string, logs_string) = self.restore_output()
  91
  92         if hasattr(testcase, 'assertMultiLineEqual'):
  93             testassert = testcase.assertMultiLineEqual
  94         else:
  95             testassert = testcase.assertEqual
  96
  97         testassert(stdout_string, expected_stdout)
  98         testassert(stderr_string, expected_stderr)
  99         if expected_logs is not None:
 100             testassert(logs_string, expected_logs)
 101         # This is a little strange, but I don't know where else to return this information.
 102         return return_value
 103
 104
 105 class OutputCaptureTestCaseBase(unittest.TestCase):
 106     maxDiff = None
 107
 108     def setUp(self):
 109         unittest.TestCase.setUp(self)
 110         self.output_capture = OutputCapture()
 111         (self.__captured_stdout, self.__captured_stderr) = self.output_capture.capture_output()
 112
 113     def tearDown(self):
 114         del self.__captured_stdout
 115         del self.__captured_stderr
 116         self.output_capture.restore_output()
 117         unittest.TestCase.tearDown(self)
 118
 119     def assertStdout(self, expected_stdout):
 120         self.assertEqual(expected_stdout, self.__captured_stdout.getvalue())
 121
 122     def assertStderr(self, expected_stderr):
 123         self.assertEqual(expected_stderr, self.__captured_stderr.getvalue())