Simplify and add comments to copy-existing-baselines-internal test.

The purpose of this CL is to improve the readability of this test, to
try to better indicate what webkit-patch copy-existing-baselines-internal
does.

Review-Url: https://codereview.chromium.org/2392173002
Cr-Commit-Position: refs/heads/master@{#423747}

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_unittest.py

@@ -109,150 +109,120 @@ class TestCopyExistingBaselinesInternal(BaseTestCase):
     def setUp(self):
         super(TestCopyExistingBaselinesInternal, self).setUp()
 
-    def test_copying_overwritten_baseline(self):
-        self.tool.executive = MockExecutive2()
+    def options(self, **kwargs):
+        options_dict = {
+            'results_directory': None,
+            'suffixes': 'txt',
+            'verbose': False,
+        }
+        options_dict.update(kwargs)
+        return optparse.Values(options_dict)
 
-        port = self.tool.port_factory.get('test-mac-mac10.10')
+    def test_copy_baseline_mac(self):
+        port = self.tool.port_factory.get('test-mac-mac10.11')
         self._write(
             port.host.filesystem.join(
                 port.layout_tests_dir(),
-                'platform/test-mac-mac10.10/failures/expected/image-expected.txt'),
+                'platform/test-mac-mac10.11/failures/expected/image-expected.txt'),
             'original mac10.11 result')
+        self.assertFalse(self.tool.filesystem.exists(
+            self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-mac-mac10.10/failures/expected/image-expected.txt')))
 
-        oc = OutputCapture()
-        try:
-            options = optparse.Values({
-                'builder': "MOCK Mac10.11",
-                'suffixes': 'txt',
-                'verbose': True,
-                'test': "failures/expected/image.html",
-                'results_directory': None
-            })
-            oc.capture_output()
-            self.command.execute(options, [], self.tool)
-        finally:
-            out, _, _ = oc.restore_output()
+        self.command.execute(self.options(builder='MOCK Mac10.11', test='failures/expected/image.html'), [], self.tool)
 
-        self.assertMultiLineEqual(
+        # The Mac 10.11 baseline is copied over to the Mac 10.10 directory,
+        # because Mac10.10 is the "immediate predecessor" in the fallback tree.
+        # That means that normally for Mac10.10 if there's no Mac10.10-specific
+        # baseline, then we fall back to the Mac10.11 baseline.
+        # The idea is, if in the next step we download new baselines for Mac10.11
+        # but not Mac10.10, then mac10.10 will still have the correct baseline.
+        self.assertEqual(
+            self._read(self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-mac-mac10.11/failures/expected/image-expected.txt')),
+            'original mac10.11 result')
+        self.assertEqual(
             self._read(self.tool.filesystem.join(
                 port.layout_tests_dir(),
                 'platform/test-mac-mac10.10/failures/expected/image-expected.txt')),
             'original mac10.11 result')
-        self.assertMultiLineEqual(out, '{"add": [], "remove-lines": [], "delete": []}\n')
-
-    def test_copying_overwritten_baseline_to_multiple_locations(self):
-        self.tool.executive = MockExecutive2()
 
+    def test_copy_baseline_win7_to_linux_trusty(self):
         port = self.tool.port_factory.get('test-win-win7')
         self._write(
-            port.host.filesystem.join(port.layout_tests_dir(), 'platform/test-win-win7/failures/expected/image-expected.txt'),
+            self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-win-win7/failures/expected/image-expected.txt'),
             'original win7 result')
+        self.assertFalse(self.tool.filesystem.exists(
+            self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-linux-trusty/failures/expected/image-expected.txt')))
 
-        oc = OutputCapture()
-        try:
-            options = optparse.Values({
-                'builder': "MOCK Win7",
-                'suffixes': "txt",
-                'verbose': True,
-                'test': "failures/expected/image.html",
-                'results_directory': None
-            })
-            oc.capture_output()
-            self.command.execute(options, [], self.tool)
-        finally:
-            out, _, _ = oc.restore_output()
+        self.command.execute(self.options(builder='MOCK Win7', test='failures/expected/image.html'), [], self.tool)
 
-        self.assertMultiLineEqual(
+        # The Mac Win7 baseline is copied over to the Linux Trusty directory,
+        # because Linux Trusty is the baseline fallback "immediate predecessor" of Win7.
+        self.assertEqual(
+            self._read(self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-win-win7/failures/expected/image-expected.txt')),
+            'original win7 result')
+        self.assertEqual(
             self._read(self.tool.filesystem.join(
                 port.layout_tests_dir(),
                 'platform/test-linux-trusty/failures/expected/image-expected.txt')),
             'original win7 result')
-        self.assertFalse(self.tool.filesystem.exists(self.tool.filesystem.join(
-            port.layout_tests_dir(), 'platform/test-linux-precise/userscripts/another-test-expected.txt')))
-        self.assertFalse(self.tool.filesystem.exists(self.tool.filesystem.join(
-            port.layout_tests_dir(), 'platform/test-mac-mac10.10/userscripts/another-test-expected.txt')))
-        self.assertMultiLineEqual(out, '{"add": [], "remove-lines": [], "delete": []}\n')
 
     def test_no_copy_existing_baseline(self):
-        self.tool.executive = MockExecutive2()
-
         port = self.tool.port_factory.get('test-win-win7')
         self._write(
-            port.host.filesystem.join(
+            self.tool.filesystem.join(
                 port.layout_tests_dir(),
                 'platform/test-win-win7/failures/expected/image-expected.txt'),
             'original win7 result')
+        self._write(
+            self.tool.filesystem.join(
+                port.layout_tests_dir(),
+                'platform/test-linux-trusty/failures/expected/image-expected.txt'),
+            'original linux trusty result')
 
-        oc = OutputCapture()
-        try:
-            options = optparse.Values({
-                'builder': "MOCK Win7",
-                'suffixes': "txt",
-                'verbose': True,
-                'test': "failures/expected/image.html",
-                'results_directory': None
-            })
-            oc.capture_output()
-            self.command.execute(options, [], self.tool)
-        finally:
-            out, _, _ = oc.restore_output()
+        self.command.execute(self.options(builder='MOCK Win7', test='failures/expected/image.html'), [], self.tool)
 
-        self.assertMultiLineEqual(
+        # Since a baseline existed already for Linux Trusty, the Win7 baseline is not copied over.
+        self.assertEqual(
             self._read(self.tool.filesystem.join(
                 port.layout_tests_dir(),
-                'platform/test-linux-trusty/failures/expected/image-expected.txt')),
+                'platform/test-win-win7/failures/expected/image-expected.txt')),
             'original win7 result')
-        self.assertMultiLineEqual(
+        self.assertEqual(
             self._read(self.tool.filesystem.join(
                 port.layout_tests_dir(),
-                'platform/test-win-win7/failures/expected/image-expected.txt')),
-            'original win7 result')
-        self.assertFalse(self.tool.filesystem.exists(self.tool.filesystem.join(
-            port.layout_tests_dir(), 'platform/test-mac-mac10.10/userscripts/another-test-expected.txt')))
-        self.assertMultiLineEqual(out, '{"add": [], "remove-lines": [], "delete": []}\n')
+                'platform/test-linux-trusty/failures/expected/image-expected.txt')),
+            'original linux trusty result')
 
     def test_no_copy_skipped_test(self):
-        self.tool.executive = MockExecutive2()
         port = self.tool.port_factory.get('test-win-win7')
-        fs = self.tool.filesystem
         self._write(
-            fs.join(
+            self.tool.filesystem.join(
                 port.layout_tests_dir(),
                 'platform/test-win-win7/failures/expected/image-expected.txt'),
             'original win7 result')
-        expectations_path = fs.join(port.path_to_generic_test_expectations_file())
         self._write(
-            expectations_path,
+            port.path_to_generic_test_expectations_file(),
             ("[ Win ] failures/expected/image.html [ Failure ]\n"
              "[ Linux ] failures/expected/image.html [ Skip ]\n"))
-        oc = OutputCapture()
-        try:
-            options = optparse.Values({
-                'builder': "MOCK Win7",
-                'suffixes': "txt", 'verbose': True,
-                'test': "failures/expected/image.html",
-                'results_directory': None
-            })
-            oc.capture_output()
-            self.command.execute(options, [], self.tool)
-        finally:
-            oc.restore_output()
 
+        self.command.execute(self.options(builder='MOCK Win7', test='failures/expected/image.html'), [], self.tool)
+
+        # The Win7 baseline is not copied over to the Linux Trusty directory
+        # because the test is skipped on linux.
         self.assertFalse(
-            fs.exists(fs.join(
-                port.layout_tests_dir(),
-                'platform/test-mac-mac10.10/failures/expected/image-expected.txt')))
-        self.assertFalse(
-            fs.exists(fs.join(
+            self.tool.filesystem.exists(self.tool.filesystem.join(
                 port.layout_tests_dir(),
                 'platform/test-linux-trusty/failures/expected/image-expected.txt')))
-        self.assertFalse(
-            fs.exists(fs.join(
-                port.layout_tests_dir(),
-                'platform/test-linux-precise/failures/expected/image-expected.txt')))
-        self.assertEqual(
-            self._read(fs.join(port.layout_tests_dir(), 'platform/test-win-win7/failures/expected/image-expected.txt')),
-            'original win7 result')
 
 
 class TestRebaselineTest(BaseTestCase):