webkitpy: Add contextmanager to disable logging for a block

https://bugs.webkit.org/show_bug.cgi?id=172876

Reviewed by Daniel Bates.

Add a context manager which will use an OutputCapture object to capture logging
in a block and hold it in a variable.

* Scripts/webkitpy/common/system/outputcapture.py:
(OutputCaptureScope):
(OutputCaptureScope.__init__): Construct with OutputCapture object.
(OutputCaptureScope.__enter__): Begin capturing output.
(OutputCaptureScope.__exit__): Restore output and save captured output to a variable.
output and retain the resulting log.
* Scripts/webkitpy/common/system/outputcapture_unittest.py:
(OutputCaptureTest.test_output_capture_scope): Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@217758 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Tools/ChangeLog

@@ -1,3 +1,22 @@
+2017-06-03  Jonathan Bedard  <jbedard@apple.com>
+
+        webkitpy: Add contextmanager to disable logging for a block
+        https://bugs.webkit.org/show_bug.cgi?id=172876
+
+        Reviewed by Daniel Bates.
+
+        Add a context manager which will use an OutputCapture object to capture logging
+        in a block and hold it in a variable.
+
+        * Scripts/webkitpy/common/system/outputcapture.py:
+        (OutputCaptureScope):
+        (OutputCaptureScope.__init__): Construct with OutputCapture object.
+        (OutputCaptureScope.__enter__): Begin capturing output. 
+        (OutputCaptureScope.__exit__): Restore output and save captured output to a variable.
+        output and retain the resulting log.
+        * Scripts/webkitpy/common/system/outputcapture_unittest.py:
+        (OutputCaptureTest.test_output_capture_scope): Added.
+
 2017-06-02  Zalan Bujtas  <zalan@apple.com>
 
         Cleanup FrameView::autoSizeIfEnabled.

Tools/Scripts/webkitpy/common/system/outputcapture.py

@@ -107,6 +107,19 @@ def assert_outputs(self, testcase, function, args=[], kwargs={}, expected_stdout
         return return_value
 
 
+class OutputCaptureScope(object):
+
+    def __init__(self, output_capture=OutputCapture()):
+        self._output_capture = output_capture
+        self.captured_output = (None, None, None)
+
+    def __enter__(self):
+        self._output_capture.capture_output()
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.captured_output = self._output_capture.restore_output()
+
+
 class OutputCaptureTestCaseBase(unittest.TestCase):
     maxDiff = None
 

Tools/Scripts/webkitpy/common/system/outputcapture_unittest.py

@@ -23,7 +23,7 @@
 import logging
 import unittest
 
-from webkitpy.common.system.outputcapture import OutputCapture
+from webkitpy.common.system.outputcapture import OutputCapture, OutputCaptureScope
 
 
 _log = logging.getLogger(__name__)
@@ -57,3 +57,19 @@ def test_set_log_level(self):
         self.output.set_log_level(logging.WARN)
         self.log_all_levels()
         self.assertLogged('ERROR\nCRITICAL\nWARN\nERROR\nCRITICAL\n')
+
+    def test_output_capture_scope(self):
+        scope = OutputCaptureScope()
+        with scope:
+            print 'STRING 1'
+        self.assertEqual(('STRING 1\n', '', ''), scope.captured_output)
+
+        with scope:
+            print 'STRING 2'
+        self.assertEqual(('STRING 2\n', '', ''), scope.captured_output)
+
+    def test_output_capture_scope_from_output_capture(self):
+        scope = OutputCaptureScope(self.output)
+        with scope:
+            self.log_all_levels()
+        self.assertEqual(('', '', 'INFO\nWARN\nERROR\nCRITICAL\n'), scope.captured_output)