Refactor gpu_tests unit tests by using mock.patch

Instead of setting class member functions to MagicMock classes and making
sure that they are set back to their original values at the end of a test
within a finally block, we can use a with block by using mock.patch.object
to patch member functions of a class. Also updates the sanitization of the
tags returned from GetPlatformTags. Since tags are case insensitive we can
remove the lower function call. We can also replace the chain of replace
calls with one re.sub call to change spaces and underscores to dashes.

Bug: chromium:976505
Change-Id: Ic8b5da86ef711d5698916fef40da0ed439b8ce49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1670024
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671508}

content/test/gpu/gpu_tests/gpu_integration_test.py

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import logging
+import re
 
 from telemetry.testing import serially_executed_browser_test_case
 from telemetry.util import screenshot
@@ -303,9 +304,8 @@ class GpuIntegrationTest(
         gpu_device_tag = '%s-%s' % (gpu_vendor, gpu_device_id)
       angle_renderer = gpu_helper.GetANGLERenderer(gpu_info)
       cmd_decoder = gpu_helper.GetCommandDecoder(gpu_info)
-      # all spaces in the tag will be replaced by '-', and all letters will
-      # be converted to its lower case form.
-      tags.extend([tag.lower().replace(' ', '-').replace('_', '-') for tag in [
+      # all spaces and underscores in the tag will be replaced by dashes
+      tags.extend([re.sub('[ _]', '-', tag) for tag in [
           gpu_vendor, gpu_device_tag, angle_renderer, cmd_decoder]])
     # If additional options have been set via '--extra-browser-args' check for
     # those which map to expectation tags. The '_browser_backend' attribute may

content/test/gpu/gpu_tests/gpu_integration_test_unittest.py

@@ -52,34 +52,24 @@ def _GetSystemInfo(
 
 
 def _GetTagsToTest(browser, test_class=None, args=None):
-  gpu_tests = test_class or gpu_integration_test.GpuIntegrationTest
-  expectations_fn = gpu_tests.ExpectationsFiles
-  gpu_tests.ExpectationsFiles = mock.MagicMock(return_value=['exp.txt'])
-  ret = None
-  try:
+  test_class = test_class or gpu_integration_test.GpuIntegrationTest
+  with mock.patch.object(
+      test_class, 'ExpectationsFiles', return_value=['exp.txt']):
     possible_browser = fakes.FakePossibleBrowser()
     possible_browser._returned_browser = browser
     args = args or gpu_helper.GetMockArgs()
-    ret = set(gpu_tests.GenerateTags(args, possible_browser))
-  finally:
-    gpu_tests.ExpectationsFiles = expectations_fn
-  return ret
+    return set(test_class.GenerateTags(args, possible_browser))
 
 
 def _GenerateNvidiaExampleTagsForTestClassAndArgs(test_class, args):
-  exp_files_fn = test_class.ExpectationsFiles
-  ret = None
-  try:
-    test_class.ExpectationsFiles = mock.MagicMock(return_value=['exp.txt'])
+  with mock.patch.object(
+      test_class, 'ExpectationsFiles', return_value=['exp.txt']):
     _ = [_ for _ in test_class.GenerateGpuTests(args)]
     platform = fakes.FakePlatform('win', 'win10')
     browser = fakes.FakeBrowser(platform, 'release')
     browser._returned_system_info = _GetSystemInfo(
         gpu=VENDOR_NVIDIA, device=0x1cb3, gl_renderer='ANGLE Direct3D9')
-    ret = _GetTagsToTest(browser, test_class)
-  finally:
-    test_class.ExpectationsFiles = exp_files_fn
-  return ret
+    return _GetTagsToTest(browser, test_class)
 
 
 class GpuIntegrationTestUnittest(unittest.TestCase):
@@ -195,7 +185,7 @@ class GpuIntegrationTestUnittest(unittest.TestCase):
     self.assertEqual(
         _GetTagsToTest(browser),
         set(['mac', 'mojave', 'release', 'imagination',
-             'imagination-powervr-sgx-554',
+             'imagination-PowerVR-SGX-554',
              'opengles', 'passthrough']))
 
   def testGenerateVendorTagUsingDeviceString(self):
@@ -207,7 +197,7 @@ class GpuIntegrationTestUnittest(unittest.TestCase):
     self.assertEqual(
         _GetTagsToTest(browser),
         set(['mac', 'mojave', 'release', 'imagination',
-             'imagination-triangle-monster-3000',
+             'imagination-Triangle-Monster-3000',
              'no-angle', 'no-passthrough']))
 
   def testSimpleIntegrationTest(self):

content/test/gpu/gpu_tests/test_expectations_unittest.py

@@ -207,16 +207,11 @@ def _TestCheckTestExpectationsAreForExistingTests(expectations):
   expectations_file.write(expectations)
   expectations_file.close()
   gpu_tests = gpu_integration_test.GpuIntegrationTest
-  generate_gpu_fn = gpu_tests.GenerateGpuTests
-  expectations_files_fn = gpu_tests.ExpectationsFiles
-  gpu_tests.GenerateGpuTests = mock.MagicMock(return_value=[('a/b/c', ())])
-  gpu_tests.ExpectationsFiles = mock.MagicMock(
-      return_value=[expectations_file.name])
-  try:
-    CheckTestExpectationsAreForExistingTests(gpu_tests, options)
-  finally:
-    gpu_tests.GenerateGpuTests = generate_gpu_fn
-    gpu_tests.ExpectationsFiles = expectations_files_fn
+  with mock.patch.object(
+      gpu_tests, 'GenerateGpuTests', return_value=[('a/b/c', ())]):
+    with mock.patch.object(
+        gpu_tests, 'ExpectationsFiles', return_value=[expectations_file.name]):
+      CheckTestExpectationsAreForExistingTests(gpu_tests, options)
 
 
 def _CheckPatternIsValid(pattern):