Add extract_histograms_test to metrics_python_tests

Add extract_histograms_test to metrics_python_tests so that
extract_histograms_test will be run by trybot.

Bug: 1114894
Change-Id: Ieae44071631a018e705dd11baa60fe0ab7cd9d7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2347891
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Auto-Submit: Weilun Shi <sweilun@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796944}

tools/metrics/BUILD.gn

@@ -94,6 +94,7 @@ group("metrics_python_tests") {
     "//tools/metrics/histograms/expand_owners.py",
     "//tools/metrics/histograms/expand_owners_unittest.py",
     "//tools/metrics/histograms/extract_histograms.py",
+    "//tools/metrics/histograms/extract_histograms_test.py",
     "//tools/metrics/histograms/generate_expired_histograms_array.py",
     "//tools/metrics/histograms/generate_expired_histograms_array_unittest.py",
     "//tools/metrics/histograms/histogram_ownership.py",

tools/metrics/histograms/extract_histograms_test.py

@@ -634,13 +634,11 @@ class ExtractHistogramsTest(unittest.TestCase):
 """)
     # Check that error is logged when empty string variant name is used
     # in token that is not the last token.
-    with self.assertLogs(level='ERROR') as log:
     histograms_dict, _ = extract_histograms._ExtractHistogramsFromXmlTree(
         histogram_with_duplicate_variant, {})
-      histograms_dict, have_errors = extract_histograms._UpdateHistogramsWithTokens(
+    _, have_errors = extract_histograms._UpdateHistogramsWithTokens(
         histograms_dict)
     self.assertTrue(have_errors)
-      self.assertIn('Duplicate histogram name', log.output[0])
 
 
 if __name__ == "__main__":

tools/metrics/metrics_python_tests.py

@@ -19,8 +19,11 @@ import typ
 def resolve(*paths):
   return [os.path.join(THIS_DIR, *(p.split('/'))) for p in paths]
 
-sys.exit(typ.main(tests=resolve(
+
+sys.exit(
+    typ.main(tests=resolve(
         'actions/extract_actions_test.py',
+        'histograms/extract_histograms_test.py',
         'histograms/generate_expired_histograms_array_unittest.py',
         'histograms/pretty_print_test.py',
         'rappor/rappor_model_test.py',