diff --git a/tools/run_tests/filter_pull_request_tests.py b/tools/run_tests/filter_pull_request_tests.py
index b7ebe20..981fbe3 100644
--- a/tools/run_tests/filter_pull_request_tests.py
+++ b/tools/run_tests/filter_pull_request_tests.py
@@ -31,7 +31,7 @@
 """Filter out tests based on file differences compared to merge target branch"""
 
 import re
-from subprocess import call, check_output
+from subprocess import check_output
 
 
 class TestSuite:
@@ -105,7 +105,7 @@
   'config\.m4$': [_PHP_TEST_SUITE],
   'CONTRIBUTING\.md$': [],
   'Gemfile$': [_RUBY_TEST_SUITE],
-  'grpc.def$': [_WINDOWS_TEST_SUITE],
+  'grpc\.def$': [_WINDOWS_TEST_SUITE],
   'grpc\.gemspec$': [_RUBY_TEST_SUITE],
   'gRPC\.podspec$': [_OBJC_TEST_SUITE],
   'gRPC\-Core\.podspec$': [_OBJC_TEST_SUITE],
@@ -172,15 +172,11 @@
   :param tests: list of all tests generated by run_tests_matrix.py
   :return: list of relevant tests
   """
-  print("Finding file differences between gRPC %s branch and pull request...\n" % base_branch)
+  print('Finding file differences between gRPC %s branch and pull request...\n' % base_branch)
   changed_files = _get_changed_files(base_branch)
   for changed_file in changed_files:
-    print("  %s" % changed_file)
-  print
-
-  # todo(mattkwong): Remove this
-  # Faking changed files to test test filtering on Jenkins
-  changed_files = ['src/node/something', 'src/python/something']
+    print('  %s' % changed_file)
+  print('')
 
   # Regex that combines all keys in _WHITELIST_DICT
   all_triggers = "(" + ")|(".join(_WHITELIST_DICT.keys()) + ")"
@@ -193,8 +189,8 @@
   for test_suite in _ALL_TEST_SUITES:
     if _can_skip_tests(changed_files, test_suite.triggers):
       for label in test_suite.labels:
-        print("  %s tests safe to skip" % label)
+        print('  %s tests safe to skip' % label)
         skippable_labels.append(label)
-
   tests = _remove_irrelevant_tests(tests, skippable_labels)
   return tests
+
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index ae8cb85..25fbe81 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -231,112 +231,110 @@
   return sorted(all_labels)
 
 
-argp = argparse.ArgumentParser(description='Run a matrix of run_tests.py tests.')
-argp.add_argument('-j', '--jobs',
-                  default=multiprocessing.cpu_count()/_DEFAULT_INNER_JOBS,
-                  type=int,
-                  help='Number of concurrent run_tests.py instances.')
-argp.add_argument('-f', '--filter',
-                  choices=_allowed_labels(),
-                  nargs='+',
-                  default=[],
-                  help='Filter targets to run by label with AND semantics.')
-argp.add_argument('--build_only',
-                  default=False,
-                  action='store_const',
-                  const=True,
-                  help='Pass --build_only flag to run_tests.py instances.')
-argp.add_argument('--force_default_poller', default=False, action='store_const', const=True,
-                  help='Pass --force_default_poller to run_tests.py instances.')
-argp.add_argument('--dry_run',
-                  default=False,
-                  action='store_const',
-                  const=True,
-                  help='Only print what would be run.')
-argp.add_argument('--filter_pr_tests',
-	          default=False,
-		  action='store_const',	
-		  const=True,	  
-		  help='Filters out tests irrelavant to pull request changes.')
-argp.add_argument('--base_branch',
-                  default='origin/master',
-                  type=str,
-                  help='Branch that pull request is requesting to merge into')
-argp.add_argument('--inner_jobs',
-                  default=_DEFAULT_INNER_JOBS,
-                  type=int,
-                  help='Number of jobs in each run_tests.py instance')
-args = argp.parse_args()
+if __name__ == "__main__":
+  argp = argparse.ArgumentParser(description='Run a matrix of run_tests.py tests.')
+  argp.add_argument('-j', '--jobs',
+                    default=multiprocessing.cpu_count()/_DEFAULT_INNER_JOBS,
+                    type=int,
+                    help='Number of concurrent run_tests.py instances.')
+  argp.add_argument('-f', '--filter',
+                    choices=_allowed_labels(),
+                    nargs='+',
+                    default=[],
+                    help='Filter targets to run by label with AND semantics.')
+  argp.add_argument('--build_only',
+                    default=False,
+                    action='store_const',
+                    const=True,
+                    help='Pass --build_only flag to run_tests.py instances.')
+  argp.add_argument('--force_default_poller', default=False, action='store_const', const=True,
+                    help='Pass --force_default_poller to run_tests.py instances.')
+  argp.add_argument('--dry_run',
+                    default=False,
+                    action='store_const',
+                    const=True,
+                    help='Only print what would be run.')
+  argp.add_argument('--filter_pr_tests',
+                    default=False,
+                    action='store_const',
+                    const=True,
+                    help='Filters out tests irrelavant to pull request changes.')
+  argp.add_argument('--base_branch',
+                    default='origin/master',
+                    type=str,
+                    help='Branch that pull request is requesting to merge into')
+  argp.add_argument('--inner_jobs',
+                    default=_DEFAULT_INNER_JOBS,
+                    type=int,
+                    help='Number of jobs in each run_tests.py instance')
+  args = argp.parse_args()
 
+  extra_args = []
+  if args.build_only:
+    extra_args.append('--build_only')
+  if args.force_default_poller:
+    extra_args.append('--force_default_poller')
 
-extra_args = []
-if args.build_only:
-  extra_args.append('--build_only')
-if args.force_default_poller:
-  extra_args.append('--force_default_poller')
+  all_jobs = _create_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs) + \
+             _create_portability_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs)
 
-all_jobs = _create_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs) + \
-           _create_portability_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs)
+  jobs = []
+  for job in all_jobs:
+    if not args.filter or all(filter in job.labels for filter in args.filter):
+      jobs.append(job)
 
-jobs = []
-for job in all_jobs:
-  if not args.filter or all(filter in job.labels for filter in args.filter):
-    jobs.append(job)
+  if not jobs:
+    jobset.message('FAILED', 'No test suites match given criteria.',
+                   do_newline=True)
+    sys.exit(1)
 
-if not jobs:
-  jobset.message('FAILED', 'No test suites match given criteria.',
-                 do_newline=True)
-  sys.exit(1)
+  print('IMPORTANT: The changes you are testing need to be locally committed')
+  print('because only the committed changes in the current branch will be')
+  print('copied to the docker environment or into subworkspaces.')
 
-print('IMPORTANT: The changes you are testing need to be locally committed')
-print('because only the committed changes in the current branch will be')
-print('copied to the docker environment or into subworkspaces.')
+  skipped_jobs = []
 
-skipped_jobs = []
-if args.filter_pr_tests:
-  print 'Looking for irrelevant tests to skip...'
-  relevant_jobs = filter_tests(jobs, args.base_branch)
-  print
-  if len(relevant_jobs) == len(jobs):
-    print 'No tests will be skipped.'
-  else:
-    print 'These tests will be skipped:'
-    skipped_jobs = set(jobs) - set(relevant_jobs)
-    for job in list(skipped_jobs):
-      print '  %s' % job.shortname
-  jobs = relevant_jobs
+  if args.filter_pr_tests:
+    print('Looking for irrelevant tests to skip...')
+    relevant_jobs = filter_tests(jobs, args.base_branch)
+    if len(relevant_jobs) == len(jobs):
+      print('No tests will be skipped.')
+    else:
+      print('These tests will be skipped:')
+      skipped_jobs = [job for job in jobs if job not in relevant_jobs]
+      for job in list(skipped_jobs):
+        print('  %s' % job.shortname)
+    jobs = relevant_jobs
+
+  print('Will run these tests:')
+  for job in jobs:
+    if args.dry_run:
+      print('  %s: "%s"' % (job.shortname, ' '.join(job.cmdline)))
+    else:
+      print('  %s' % job.shortname)
   print
 
-print 'Will run these tests:'
-for job in jobs:
   if args.dry_run:
-    print '  %s: "%s"' % (job.shortname, ' '.join(job.cmdline))
+    print('--dry_run was used, exiting')
+    sys.exit(1)
+
+  jobset.message('START', 'Running test matrix.', do_newline=True)
+  num_failures, resultset = jobset.run(jobs,
+                                       newline_on_success=True,
+                                       travis=True,
+                                       maxjobs=args.jobs)
+  # Merge skipped tests into results to show skipped tests on report.xml
+  if skipped_jobs:
+    skipped_results = jobset.run(skipped_jobs,
+                                 skip_jobs=True)
+    resultset.update(skipped_results)
+  report_utils.render_junit_xml_report(resultset, 'report.xml',
+                                       suite_name='aggregate_tests')
+
+  if num_failures == 0:
+    jobset.message('SUCCESS', 'All run_tests.py instance finished successfully.',
+                   do_newline=True)
   else:
-    print '  %s' % job.shortname
-print
-
-if args.dry_run:
-  print '--dry_run was used, exiting'
-  sys.exit(1)
-
-jobset.message('START', 'Running test matrix.', do_newline=True)
-num_failures, resultset = jobset.run(jobs,
-                                     newline_on_success=True,
-                                     travis=True,
-                                     maxjobs=args.jobs)
-# Merge skipped tests into results to show skipped tests on report.xml
-if skipped_jobs:
-  skipped_results = jobset.run(skipped_jobs,
-                               skip_jobs=True)
-  resultset.update(skipped_results)
-report_utils.render_junit_xml_report(resultset, 'report.xml',
-                                     suite_name='aggregate_tests')
-
-
-if num_failures == 0:
-  jobset.message('SUCCESS', 'All run_tests.py instance finished successfully.',
-                 do_newline=True)
-else:
-  jobset.message('FAILED', 'Some run_tests.py instance have failed.',
-                 do_newline=True)
-  sys.exit(1)
+    jobset.message('FAILED', 'Some run_tests.py instance have failed.',
+                   do_newline=True)
+    sys.exit(1)
diff --git a/tools/run_tests/sanity/check_test_filtering.py b/tools/run_tests/sanity/check_test_filtering.py
new file mode 100755
index 0000000..adcdd33
--- /dev/null
+++ b/tools/run_tests/sanity/check_test_filtering.py
@@ -0,0 +1,138 @@
+#!/usr/bin/env python2.7
+
+# Copyright 2016, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+import os
+import sys
+import unittest
+import re
+
+# hack import paths to pick up extra code
+sys.path.insert(0, os.path.abspath('tools/run_tests/'))
+from run_tests_matrix import _create_test_jobs, _create_portability_test_jobs
+import filter_pull_request_tests
+
+_LIST_OF_LANGUAGE_LABELS = ['sanity', 'c', 'c++', 'csharp', 'node', 'objc', 'php', 'php7', 'python', 'ruby']
+_LIST_OF_PLATFORM_LABELS = ['linux', 'macos', 'windows']
+
+class TestFilteringTest(unittest.TestCase):
+
+  def generate_all_tests(self):
+    all_jobs = _create_test_jobs() + _create_portability_test_jobs()
+    self.assertIsNotNone(all_jobs)
+    return all_jobs
+
+  def test_filtering(self, changed_files=[], labels=_LIST_OF_LANGUAGE_LABELS):
+    """
+    Default args should filter no tests because changed_files is empty and
+    default labels should be able to match all jobs
+    :param changed_files: mock list of changed_files from pull request
+    :param labels: list of job labels that should be skipped
+    """
+    all_jobs = self.generate_all_tests()
+    # Replacing _get_changed_files function to allow specifying changed files in filter_tests function
+    def _get_changed_files(foo):
+      return changed_files
+    filter_pull_request_tests._get_changed_files = _get_changed_files
+    print
+    filtered_jobs = filter_pull_request_tests.filter_tests(all_jobs, "test")
+
+    for label in labels:
+      for job in filtered_jobs:
+        self.assertNotIn(label, job.labels)
+
+    jobs_matching_labels = 0
+    for label in labels:
+      for job in all_jobs:
+        if (label in job.labels):
+          jobs_matching_labels += 1
+    self.assertEquals(len(filtered_jobs), len(all_jobs) - jobs_matching_labels)
+
+  def test_individual_language_filters(self):
+    # Changing unlisted file should trigger all languages
+    self.test_filtering(['ffffoo/bar.baz'], [_LIST_OF_LANGUAGE_LABELS])
+    # Changing core should trigger all tests
+    self.test_filtering(['src/core/foo.bar'], [_LIST_OF_LANGUAGE_LABELS])
+    # Testing individual languages
+    self.test_filtering(['templates/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                                filter_pull_request_tests._SANITY_TEST_SUITE.labels])
+    self.test_filtering(['test/core/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                                filter_pull_request_tests._CORE_TEST_SUITE.labels])
+    self.test_filtering(['src/cpp/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                              filter_pull_request_tests._CPP_TEST_SUITE.labels])
+    self.test_filtering(['src/csharp/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                                 filter_pull_request_tests._CSHARP_TEST_SUITE.labels])
+    self.test_filtering(['src/node/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                               filter_pull_request_tests._NODE_TEST_SUITE.labels])
+    self.test_filtering(['src/objective-c/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                                      filter_pull_request_tests._OBJC_TEST_SUITE.labels])
+    self.test_filtering(['src/php/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                              filter_pull_request_tests._PHP_TEST_SUITE.labels])
+    self.test_filtering(['src/python/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                                 filter_pull_request_tests._PYTHON_TEST_SUITE.labels])
+    self.test_filtering(['src/ruby/foo.bar'], [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                                               filter_pull_request_tests._RUBY_TEST_SUITE.labels])
+
+  def test_combined_language_filters(self):
+    self.test_filtering(['templates/foo.bar', 'test/core/foo.bar'],
+                        [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                         filter_pull_request_tests._SANITY_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._CORE_TEST_SUITE.labels])
+    self.test_filtering(['src/node/foo.bar', 'src/cpp/foo.bar', "src/csharp/foo.bar"],
+                        [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                         filter_pull_request_tests._NODE_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._CPP_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._CSHARP_TEST_SUITE.labels])
+    self.test_filtering(['src/objective-c/foo.bar', 'src/php/foo.bar', "src/python/foo.bar", "src/ruby/foo.bar"],
+                        [label for label in _LIST_OF_LANGUAGE_LABELS if label not in
+                         filter_pull_request_tests._OBJC_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._PHP_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._PYTHON_TEST_SUITE.labels and label not in
+                         filter_pull_request_tests._RUBY_TEST_SUITE.labels])
+
+  def test_platform_filter(self):
+    self.test_filtering(['vsprojects/foo.bar'], [label for label in _LIST_OF_PLATFORM_LABELS if label not in
+                                                 filter_pull_request_tests._WINDOWS_TEST_SUITE.labels])
+
+  def test_whitelist(self):
+    whitelist = filter_pull_request_tests._WHITELIST_DICT
+    files_that_should_trigger_all_tests = ['src/core/foo.bar',
+                                           'some_file_not_on_the_white_list',
+                                           'BUILD',
+                                           'etc/roots.pem',
+                                           'Makefile',
+                                           'tools/foo']
+    for key in whitelist.keys():
+      for file_name in files_that_should_trigger_all_tests:
+        self.assertFalse(re.match(key, file_name))
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/tools/run_tests/sanity/sanity_tests.yaml b/tools/run_tests/sanity/sanity_tests.yaml
index e699c51..5c2bedc 100644
--- a/tools/run_tests/sanity/sanity_tests.yaml
+++ b/tools/run_tests/sanity/sanity_tests.yaml
@@ -2,6 +2,7 @@
 - script: tools/run_tests/sanity/check_cache_mk.sh
 - script: tools/run_tests/sanity/check_sources_and_headers.py
 - script: tools/run_tests/sanity/check_submodules.sh
+- script: tools/run_tests/sanity/check_test_filtering.py
 - script: tools/buildgen/generate_projects.sh -j 3
   cpu_cost: 3
 - script: tools/distrib/check_copyright.py