Checking config file actually exist or not in tempest run

This PS will check config file passed from command line is actually
existing or not in tempest run command. If file exists, only then it
will go for set config path otherwise will fail with value error.
Also adding and modifying unit test cases for this change.

Partially-Implements: blueprint tempest-cli-unit-test-coverage

Change-Id: I09d756be69cb3a9be8d0638c41d45a089d62b238
Closes-Bug: #1808473

releasenotes/notes/bug-1808473-54ada26ab78e7b02.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed bug #1808473. ``tempest run`` CLI will error if a non-exist config file is
+    input to parameter --config-file. Earlier non-exist config value was silently
+    getting ignored and the default config file was used instead which used to give
+    false behavior to the user on using the passed config file.

tempest/cmd/run.py

@@ -103,6 +103,9 @@ from tempest.cmd import workspace
 from tempest.common import credentials_factory as credentials
 from tempest import config
 
+if six.PY2:
+    # Python 2 has not FileNotFoundError exception
+    FileNotFoundError = IOError
 
 CONF = config.CONF
 SAVED_STATE_JSON = "saved_state.json"
@@ -112,7 +115,12 @@ class TempestRun(command.Command):
 
     def _set_env(self, config_file=None):
         if config_file:
-            CONF.set_config_path(os.path.abspath(config_file))
+            if os.path.exists(os.path.abspath(config_file)):
+                CONF.set_config_path(os.path.abspath(config_file))
+            else:
+                raise FileNotFoundError(
+                    "Config file: %s doesn't exist" % config_file)
+
         # NOTE(mtreinish): This is needed so that stestr doesn't gobble up any
         # stacktraces on failure.
         if 'TESTR_PDB' in os.environ:

tempest/tests/cmd/test_run.py

@@ -29,6 +29,10 @@ from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.tests import base
 
+if six.PY2:
+    # Python 2 has not FileNotFoundError exception
+    FileNotFoundError = IOError
+
 DEVNULL = open(os.devnull, 'wb')
 atexit.register(DEVNULL.close)
 
@@ -244,14 +248,22 @@ class TestConfigPathCheck(base.TestCase):
         # getting set in os environment when some data has passed to
         # set the environment.
 
-        self.run_cmd._set_env("/fakedir/fakefile")
-        self.assertEqual("/fakedir/fakefile", CONF._path)
-        self.assertIn('TEMPEST_CONFIG_DIR', os.environ)
-        self.assertEqual("/fakedir/fakefile",
-                         os.path.join(os.environ['TEMPEST_CONFIG_DIR'],
-                                      os.environ['TEMPEST_CONFIG']))
+        _, path = tempfile.mkstemp()
+        self.addCleanup(os.remove, path)
 
-    def test_tempest_run_set_config_no_path(self):
+        self.run_cmd._set_env(path)
+        self.assertEqual(path, CONF._path)
+        self.assertIn('TEMPEST_CONFIG_DIR', os.environ)
+        self.assertEqual(path, os.path.join(os.environ['TEMPEST_CONFIG_DIR'],
+                                            os.environ['TEMPEST_CONFIG']))
+
+    def test_tempest_run_set_config_no_exist_path(self):
+        path = "fake/path"
+        self.assertRaisesRegex(FileNotFoundError,
+                               'Config file: .* doesn\'t exist',
+                               self.run_cmd._set_env, path)
+
+    def test_tempest_run_no_config_path(self):
         # Note: (mbindlish) This test is created for the bug id: 1783751
         # Checking TEMPEST_CONFIG_DIR and TEMPEST_CONFIG should have no value
         # in os environment when no data has passed to set the environment.
@@ -313,13 +325,15 @@ class TestTakeAction(base.TestCase):
 
     def test_config_file_specified(self):
         self._setup_test_dirs()
+        _, path = tempfile.mkstemp()
+        self.addCleanup(os.remove, path)
         tempest_run = run.TempestRun(app=mock.Mock(), app_args=mock.Mock())
         parsed_args = mock.Mock()
 
         parsed_args.workspace = None
         parsed_args.state = None
         parsed_args.list_tests = False
-        parsed_args.config_file = '.stestr.conf'
+        parsed_args.config_file = path
 
         with mock.patch('stestr.commands.run_command') as m:
             m.return_value = 0
@@ -341,13 +355,15 @@ class TestTakeAction(base.TestCase):
 
     def test_config_file_workspace_registered(self):
         self._setup_test_dirs()
+        _, path = tempfile.mkstemp()
+        self.addCleanup(os.remove, path)
         tempest_run = run.TempestRun(app=mock.Mock(), app_args=mock.Mock())
         parsed_args = mock.Mock()
         parsed_args.workspace = self.name
         parsed_args.workspace_path = self.store_file
         parsed_args.state = None
         parsed_args.list_tests = False
-        parsed_args.config_file = '.stestr.conf'
+        parsed_args.config_file = path
 
         with mock.patch('stestr.commands.run_command') as m:
             m.return_value = 0
@@ -406,13 +422,15 @@ class TestTakeAction(base.TestCase):
     @mock.patch('tempest.cmd.run.TempestRun._init_state')
     def test_no_workspace_config_file_state_true(self, mock_init_state):
         self._setup_test_dirs()
+        _, path = tempfile.mkstemp()
+        self.addCleanup(os.remove, path)
         tempest_run = run.TempestRun(app=mock.Mock(), app_args=mock.Mock())
         parsed_args = mock.Mock()
         parsed_args.workspace = None
         parsed_args.workspace_path = self.store_file
         parsed_args.state = True
         parsed_args.list_tests = False
-        parsed_args.config_file = '.stestr.conf'
+        parsed_args.config_file = path
 
         with mock.patch('stestr.commands.run_command') as m:
             m.return_value = 0