Add PRESUBMIT check if modified UMA histogram name can be found (2)

This CL is an iteration of http://crrev.com/766713004, that got reverted
after http://crbug.com/445265 because it could not cope correctly
with structures of the type:

<histogram_suffixes name="SafeBrowsingStores.SBWhiteLists" separator=".">
  <suffix name="CSD" label="CSD"/>
  <suffix name="DownloadWhitelist" label="DownloadWhitelist"/>
  <affected-histogram name="SB2.DatabaseKilobytes"/>
</histogram_suffixes>

(in particular: affected-histogram-suffixes).

Limitation that should be solved now.

Original description ---------------------------------------------------

Add PRESUBMIT check if modified UMA histogram name can be found

This Presubmit checks if some diffs affect any UMA_HISTOGRAM_*
macro and, if so, checks if the histogram name is to be found
in either tools/metrics/histograms/histograms.xml or in the
CL diffs.

Addresses the problem of someone modifying code and
inadvertently forgetting a corresponding histograms.xml
adaptation, that has happened in the past.

BUG=434420, 445265

Review URL: https://codereview.chromium.org/885783007

Cr-Commit-Position: refs/heads/master@{#314557}

1 files changed, 67 insertions, 0 deletions

diff --git a/PRESUBMIT_test.py b/PRESUBMIT_test.py
index 58ca402..00997b4 100755
--- a/PRESUBMIT_test.py
+++ b/PRESUBMIT_test.py
@@ -270,6 +270,73 @@ class VersionControlConflictsTest(unittest.TestCase):
     self.assertTrue('3' in errors[1])
     self.assertTrue('5' in errors[2])
 
+class UmaHistogramChangeMatchedOrNotTest(unittest.TestCase):
+  def testTypicalCorrectlyMatchedChange(self):
+    diff_cc = ['UMA_HISTOGRAM_BOOL("Bla.Foo.Dummy", true)']
+    diff_xml = ['<histogram name="Bla.Foo.Dummy"> </histogram>']
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [
+      MockFile('some/path/foo.cc', diff_cc),
+      MockFile('tools/metrics/histograms/histograms.xml', diff_xml),
+    ]
+    warnings = PRESUBMIT._CheckUmaHistogramChanges(mock_input_api,
+                                                   MockOutputApi())
+    self.assertEqual(0, len(warnings))
+
+  def testTypicalNotMatchedChange(self):
+    diff_cc = ['UMA_HISTOGRAM_BOOL("Bla.Foo.Dummy", true)']
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [MockFile('some/path/foo.cc', diff_cc)]
+    warnings = PRESUBMIT._CheckUmaHistogramChanges(mock_input_api,
+                                                   MockOutputApi())
+    self.assertEqual(1, len(warnings))
+    self.assertEqual('warning', warnings[0].type)
+
+  def testTypicalNotMatchedChangeViaSuffixes(self):
+    diff_cc = ['UMA_HISTOGRAM_BOOL("Bla.Foo.Dummy", true)']
+    diff_xml = ['<histogram_suffixes name="SuperHistogram">',
+                '  <suffix name="Dummy"/>',
+                '  <affected-histogram name="Snafu.Dummy"/>',
+                '</histogram>']
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [
+      MockFile('some/path/foo.cc', diff_cc),
+      MockFile('tools/metrics/histograms/histograms.xml', diff_xml),
+    ]
+    warnings = PRESUBMIT._CheckUmaHistogramChanges(mock_input_api,
+                                                   MockOutputApi())
+    self.assertEqual(1, len(warnings))
+    self.assertEqual('warning', warnings[0].type)
+
+  def testTypicalCorrectlyMatchedChangeViaSuffixes(self):
+    diff_cc = ['UMA_HISTOGRAM_BOOL("Bla.Foo.Dummy", true)']
+    diff_xml = ['<histogram_suffixes name="SuperHistogram">',
+                '  <suffix name="Dummy"/>',
+                '  <affected-histogram name="Bla.Foo"/>',
+                '</histogram>']
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [
+      MockFile('some/path/foo.cc', diff_cc),
+      MockFile('tools/metrics/histograms/histograms.xml', diff_xml),
+    ]
+    warnings = PRESUBMIT._CheckUmaHistogramChanges(mock_input_api,
+                                                   MockOutputApi())
+    self.assertEqual(0, len(warnings))
+
+  def testTypicalCorrectlyMatchedChangeViaSuffixesWithSeparator(self):
+    diff_cc = ['UMA_HISTOGRAM_BOOL("Snafu_Dummy", true)']
+    diff_xml = ['<histogram_suffixes name="SuperHistogram" separator="_">',
+                '  <suffix name="Dummy"/>',
+                '  <affected-histogram name="Snafu"/>',
+                '</histogram>']
+    mock_input_api = MockInputApi()
+    mock_input_api.files = [
+      MockFile('some/path/foo.cc', diff_cc),
+      MockFile('tools/metrics/histograms/histograms.xml', diff_xml),
+    ]
+    warnings = PRESUBMIT._CheckUmaHistogramChanges(mock_input_api,
+                                                   MockOutputApi())
+    self.assertEqual(0, len(warnings))
 
 class BadExtensionsTest(unittest.TestCase):
   def testBadRejFile(self):