improve pull request test filtering
diff --git a/tools/run_tests/filter_pull_request_tests.py b/tools/run_tests/filter_pull_request_tests.py
index 55dab42..128370e 100644
--- a/tools/run_tests/filter_pull_request_tests.py
+++ b/tools/run_tests/filter_pull_request_tests.py
@@ -57,44 +57,68 @@
     self.triggers.append(trigger)
 
 # Create test suites
-_core_test_suite = TestSuite(['_c_'])
-_cpp_test_suite = TestSuite(['_c++_'])
-_csharp_test_suite = TestSuite(['_csharp_'])
-_node_test_suite = TestSuite(['_node_'])
-_objc_test_suite = TestSuite(['_objc_'])
-_php_test_suite = TestSuite(['_php_', '_php7_'])
-_python_test_suite = TestSuite(['_python_'])
-_ruby_test_suite = TestSuite(['_ruby'])
-_all_test_suites = [_core_test_suite, _cpp_test_suite, _csharp_test_suite,
-                    _node_test_suite, _objc_test_suite, _php_test_suite,
-                    _python_test_suite, _ruby_test_suite]
+_CORE_TEST_SUITE = TestSuite(['_c_'])
+_CPP_TEST_SUITE = TestSuite(['_c++_'])
+_CSHARP_TEST_SUITE = TestSuite(['_csharp_'])
+_NODE_TEST_SUITE = TestSuite(['_node_'])
+_OBJC_TEST_SUITE = TestSuite(['_objc_'])
+_PHP_TEST_SUITE = TestSuite(['_php_', '_php7_'])
+_PYTHON_TEST_SUITE = TestSuite(['_python_'])
+_RUBY_TEST_SUITE = TestSuite(['_ruby'])
+_ALL_TEST_SUITES = [_CORE_TEST_SUITE, _CPP_TEST_SUITE, _CSHARP_TEST_SUITE,
+                    _NODE_TEST_SUITE, _OBJC_TEST_SUITE, _PHP_TEST_SUITE,
+                    _PYTHON_TEST_SUITE, _RUBY_TEST_SUITE]
 
 # Dictionary of whitelistable files where the key is a regex matching changed files
 # and the value is a list of tests that should be run. An empty list means that
 # the changed files should not trigger any tests. Any changed file that does not
 # match any of these regexes will trigger all tests
 _WHITELIST_DICT = {
-  '^templates/.*': [],
-  '^doc/.*': [],
-  '^examples/.*': [],
-  '^summerofcode/.*': [],
-  '.*README.md$': [],
-  '.*LICENSE$': [],
-  '^src/cpp.*': [_cpp_test_suite],
-  '^src/csharp.*': [_csharp_test_suite],
-  '^src/node.*': [_node_test_suite],
-  '^src/objective-c.*': [_objc_test_suite],
-  '^src/php.*': [_php_test_suite],
-  '^src/python.*': [_python_test_suite],
-  '^src/ruby.*': [_ruby_test_suite],
-  '^test/core.*': [_core_test_suite],
-  '^test/cpp.*': [_cpp_test_suite],
-  '^test/distrib/cpp.*': [_cpp_test_suite],
-  '^test/distrib/csharp.*': [_csharp_test_suite],
-  '^test/distrib/node.*': [_node_test_suite],
-  '^test/distrib/php.*': [_php_test_suite],
-  '^test/distrib/python.*': [_python_test_suite],
-  '^test/distrib/ruby.*': [_ruby_test_suite]
+  #'^templates/.*': [_sanity_test_suite],
+  # todo(mattkwong): add sanity test suite
+  '^doc/': [],
+  '^examples/': [],
+  '^summerofcode/': [],
+  'README\.md$': [],
+  'CONTRIBUTING\.md$': [],
+  'LICENSE$': [],
+  'INSTALL\.md$': [],
+  'MANIFEST\.md$': [],
+  'PATENTS$': [],
+  'binding\.grp$': [_NODE_TEST_SUITE],
+  'gRPC\-Core\.podspec$': [_OBJC_TEST_SUITE],
+  'gRPC\-ProtoRPC\.podspec$': [_OBJC_TEST_SUITE],
+  'gRPC\-RxLibrary\.podspec$': [_OBJC_TEST_SUITE],
+  'gRPC\.podspec$': [_OBJC_TEST_SUITE],
+  'composer\.json$': [_PHP_TEST_SUITE],
+  'config\.m4$': [_PHP_TEST_SUITE],
+  'package\.json$': [_PHP_TEST_SUITE],
+  'package\.xml$': [_PHP_TEST_SUITE],
+  'PYTHON\-MANIFEST\.in$': [_PYTHON_TEST_SUITE],
+  'requirements\.txt$': [_PYTHON_TEST_SUITE],
+  'setup\.cfg$': [_PYTHON_TEST_SUITE],
+  'setup\.py$': [_PYTHON_TEST_SUITE],
+  'grpc\.gemspec$': [_RUBY_TEST_SUITE],
+  'Gemfile$': [_RUBY_TEST_SUITE],
+  # 'grpc.def$': [_WINDOWS_TEST_SUITE],
+  '^src/cpp/': [_CPP_TEST_SUITE],
+  '^src/csharp/': [_CSHARP_TEST_SUITE],
+  '^src/node/': [_NODE_TEST_SUITE],
+  '^src/objective\-c/': [_OBJC_TEST_SUITE],
+  '^src/php/': [_PHP_TEST_SUITE],
+  '^src/python/': [_PYTHON_TEST_SUITE],
+  '^src/ruby/': [_RUBY_TEST_SUITE],
+  '^test/core/': [_CORE_TEST_SUITE],
+  '^test/cpp/': [_CPP_TEST_SUITE],
+  '^test/distrib/cpp/': [_CPP_TEST_SUITE],
+  '^test/distrib/csharp/': [_CSHARP_TEST_SUITE],
+  '^test/distrib/node/': [_NODE_TEST_SUITE],
+  '^test/distrib/php/': [_PHP_TEST_SUITE],
+  '^test/distrib/python/': [_PYTHON_TEST_SUITE],
+  '^test/distrib/ruby/': [_RUBY_TEST_SUITE],
+  '^include/grpc\+\+/': [_CPP_TEST_SUITE]
+  #'^vsprojects/': [_WINDOWS_TEST_SUITE]
+  # todo(mattkwong): add windows test suite
 }
 # Add all triggers to their respective test suites
 for trigger, test_suites in _WHITELIST_DICT.iteritems():
@@ -108,7 +132,7 @@
   """
   # git fetch might need to be called on Jenkins slave
   # todo(mattkwong): remove or uncomment below after seeing if Jenkins needs this
-  # call(['git', 'fetch'])
+  call(['git', 'fetch'])
 
   # Get file changes between branch and merge-base of specified branch
   # Not combined to be Windows friendly
@@ -137,19 +161,7 @@
   :return: list of relevant tests
   """
   # todo(mattkwong): find a more reliable way to filter tests - don't use shortname
-  return [test for test in tests if tag not in test.shortname or
-          any(san_tag in test.shortname for san_tag in ['_asan', '_tsan', '_msan'])]
-
-
-def _remove_sanitizer_tests(tests):
-  """
-  Filters out sanitizer tests
-  :param tests: list of all tests generated by run_tests_matrix.py
-  :return: list of relevant tests
-  """
-  # todo(mattkwong): find a more reliable way to filter tests - don't use shortname
-  return [test for test in tests if
-          all(san_tag not in test.shortname for san_tag in ['_asan', '_tsan', '_msan'])]
+  return [test for test in tests if tag not in test.shortname]
 
 
 def filter_tests(tests, base_branch):
@@ -171,14 +183,10 @@
     if not re.match(all_triggers, changed_file):
       return(tests)
   # Filter out tests by language
-  for test_suite in _all_test_suites:
+  for test_suite in _ALL_TEST_SUITES:
     if _can_skip_tests(changed_files, test_suite.triggers):
       for tag in test_suite.tags:
         print("  Filtering %s tests" % tag)
         tests = _remove_irrelevant_tests(tests, tag)
-  # Sanitizer tests skipped if core and c++ are skipped
-  if _can_skip_tests(changed_files, _cpp_test_suite.triggers + _core_test_suite.triggers):
-    print("  Filtering Sanitizer tests")
-    tests = _remove_sanitizer_tests(tests)
 
   return tests