Add functional test for analyze-isolation flag

The --analyze-isolation stestr run flag is fairly complex and unit tests
don't really go far enough to test it's operation. So, in addition to the
unit tests it is useful to have some functional test coverage for the
flag to verify end to end operation. This commit starts the file for
doing this with a single functional test. This gives us the groundwork
to expand the testing in the future as we find more corner cases in it's
operation.

stestr/tests/files/bisect-fail-serial-tests

@@ -0,0 +1,29 @@
+# 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.
+
+import testtools
+
+FOO = None
+
+class TestFakeClass(testtools.TestCase):
+
+
+    def test_A(self):
+        global FOO
+        FOO = True
+        self.assertTrue(self.foo)
+
+    def test_B(self):
+        global FOO
+        print(FOO)
+        self.assertFalse(FOO)
+

stestr/tests/test_bisect_return_codes.py

@@ -0,0 +1,67 @@
+# 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.
+
+import os
+import shutil
+import subprocess
+import tempfile
+
+import six
+
+from stestr.tests import base
+
+
+class TestBisectReturnCodes(base.TestCase):
+    def setUp(self):
+        super(TestBisectReturnCodes, self).setUp()
+        # Setup test dirs
+        self.directory = tempfile.mkdtemp(prefix='stestr-unit')
+        self.addCleanup(shutil.rmtree, self.directory)
+        self.test_dir = os.path.join(self.directory, 'tests')
+        os.mkdir(self.test_dir)
+        # Setup Test files
+        self.testr_conf_file = os.path.join(self.directory, '.stestr.conf')
+        self.setup_cfg_file = os.path.join(self.directory, 'setup.cfg')
+        self.init_file = os.path.join(self.test_dir, '__init__.py')
+        self.setup_py = os.path.join(self.directory, 'setup.py')
+        shutil.copy('stestr/tests/files/testr-conf', self.testr_conf_file)
+        shutil.copy('setup.py', self.setup_py)
+        shutil.copy('stestr/tests/files/setup.cfg', self.setup_cfg_file)
+        shutil.copy('stestr/tests/files/__init__.py', self.init_file)
+
+        # Move around the test code
+        self.serial_fail_file = os.path.join(self.test_dir,
+                                             'test_serial_fails.py')
+        shutil.copy('stestr/tests/files/bisect-fail-serial-tests',
+                    self.serial_fail_file)
+
+        # Change directory, run wrapper and check result
+        self.addCleanup(os.chdir, os.path.abspath(os.curdir))
+        os.chdir(self.directory)
+        subprocess.call('stestr init', shell=True)
+
+    def test_bisect_serial_fail_detected(self):
+        p = subprocess.Popen(
+            "stestr run --serial", shell=True, stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+        out, err = p.communicate()
+        self.assertEqual(1, p.returncode)
+        p_analyze = subprocess.Popen(
+            "stestr run --analyze-isolation", shell=True,
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        out, err = p_analyze.communicate()
+        out = out.decode('utf-8')
+        lines = six.text_type(out.rstrip()).splitlines()
+        self.assertEqual(3, p_analyze.returncode)
+        last_line = ('tests.test_serial_fails.TestFakeClass.test_B  '
+                     'tests.test_serial_fails.TestFakeClass.test_A')
+        self.assertEqual(last_line, lines[-1])