Add TESTBRIDGE_TEST_RUNNER_FAIL_FAST to Python tests

 - Suppport Bazel protocol to stop test runner execution upon first failure.
 - Reduces test failure result latency by returning the test action as soon as it fails
 - Implemented using TESTBRIDGE env variable (similar to --testonly bazel protocol)

  Bazel flag: --test_runner_fail_fast
  Environment variable: TESTBRIDGE_TEST_RUNNER_FAIL_FAST=1
  Change on test runners: Stop and return upon first test failure if TESTBRIDGE_TEST_FAIL_FAST=1

PiperOrigin-RevId: 296536496
Change-Id: I6d9002525625eed8c137230097bcefd73961e969

2 files changed, 153 insertions, 0 deletions

diff --git a/absl/testing/tests/absltest_fail_fast_test.py b/absl/testing/tests/absltest_fail_fast_test.py
new file mode 100644
index 0000000..83a6c76
--- /dev/null
+++ b/absl/testing/tests/absltest_fail_fast_test.py
@@ -0,0 +1,106 @@
+# Copyright 2020 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for test fail fast protocol."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+import subprocess
+
+from absl import logging
+from absl.testing import _bazelize_command
+from absl.testing import absltest
+
+
+class TestFailFastTest(absltest.TestCase):
+  """Integration tests: Runs a test binary with fail fast.
+
+  This is done by setting the fail fast environment variable
+  """
+
+  def setUp(self):
+    self._test_name = 'absl/testing/tests/absltest_fail_fast_test_helper'
+
+  def _run_fail_fast(self, fail_fast):
+    """Runs the py_test binary in a subprocess.
+
+    Args:
+      fail_fast: string, the fail fast value.
+
+    Returns:
+      (stdout, exit_code) tuple of (string, int).
+    """
+    env = {}
+    if 'SYSTEMROOT' in os.environ:
+      # This is used by the random module on Windows to locate crypto
+      # libraries.
+      env['SYSTEMROOT'] = os.environ['SYSTEMROOT']
+    additional_args = []
+    if fail_fast is not None:
+      env['TESTBRIDGE_TEST_RUNNER_FAIL_FAST'] = fail_fast
+
+    proc = subprocess.Popen(
+        args=([_bazelize_command.get_executable_path(self._test_name)]
+              + additional_args),
+        env=env,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+        universal_newlines=True)
+    stdout = proc.communicate()[0]
+
+    logging.info('output: %s', stdout)
+    return stdout, proc.wait()
+
+  def test_no_fail_fast(self):
+    out, exit_code = self._run_fail_fast(None)
+    self.assertEqual(1, exit_code)
+    self.assertIn('class A test A', out)
+    self.assertIn('class A test B', out)
+    self.assertIn('class A test C', out)
+    self.assertIn('class A test D', out)
+    self.assertIn('class A test E', out)
+
+  def test_empty_fail_fast(self):
+    out, exit_code = self._run_fail_fast('')
+    self.assertEqual(1, exit_code)
+    self.assertIn('class A test A', out)
+    self.assertIn('class A test B', out)
+    self.assertIn('class A test C', out)
+    self.assertIn('class A test D', out)
+    self.assertIn('class A test E', out)
+
+  def test_fail_fast_1(self):
+    out, exit_code = self._run_fail_fast('1')
+    self.assertEqual(1, exit_code)
+    self.assertIn('class A test A', out)
+    self.assertIn('class A test B', out)
+    self.assertIn('class A test C', out)
+    self.assertNotIn('class A test D', out)
+    self.assertNotIn('class A test E', out)
+
+  def test_fail_fast_0(self):
+    out, exit_code = self._run_fail_fast('0')
+    self.assertEqual(1, exit_code)
+    self.assertIn('class A test A', out)
+    self.assertIn('class A test B', out)
+    self.assertIn('class A test C', out)
+    self.assertIn('class A test D', out)
+    self.assertIn('class A test E', out)
+
+
+if __name__ == '__main__':
+  absltest.main()
diff --git a/absl/testing/tests/absltest_fail_fast_test_helper.py b/absl/testing/tests/absltest_fail_fast_test_helper.py
new file mode 100644
index 0000000..c684d12
--- /dev/null
+++ b/absl/testing/tests/absltest_fail_fast_test_helper.py
@@ -0,0 +1,47 @@
+# Copyright 2020 The Abseil Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""A helper test program for absltest_fail_fast_test."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import sys
+
+from absl.testing import absltest
+
+
+class ClassA(absltest.TestCase):
+  """Helper test case A for absltest_fail_fast_test."""
+
+  def testA(self):
+    sys.stderr.write('\nclass A test A\n')
+
+  def testB(self):
+    sys.stderr.write('\nclass A test B\n')
+
+  def testC(self):
+    sys.stderr.write('\nclass A test C\n')
+    self.fail('Force failure')
+
+  def testD(self):
+    sys.stderr.write('\nclass A test D\n')
+
+  def testE(self):
+    sys.stderr.write('\nclass A test E\n')
+
+
+if __name__ == '__main__':
+  absltest.main()