test-bots: Add option to use pytest for running tests.

* Add pytest to requirements.txt
* Add pass-through option to run pytest in verbose mode
* Use various default pytest options
* Exclude merels bot for now

requirements.txt

@@ -3,6 +3,7 @@ twine
 coverage>=4.4.1
 pycodestyle==2.3.1
 mock
+pytest
 -e ./zulip
 -e ./zulip_bots
 -e ./zulip_botserver

tools/test-bots

@@ -9,6 +9,7 @@ import argparse
 import glob
 import unittest
 from unittest import TestCase, TestSuite
+import pytest
 
 def parse_args():
     description = """
@@ -50,6 +51,14 @@ the tests for xkcd and wikipedia bots):
                         default=False,
                         action="store_true",
                         help="whether to exit if a bot has tests which won't run due to no __init__.py")
+    parser.add_argument('--pytest', '-p',
+                        default=False,
+                        action='store_true',
+                        help="run tests with pytest")
+    parser.add_argument('--verbose', '-v',
+                        default=False,
+                        action='store_true',
+                        help='show verbose output (with pytest)')
     return parser.parse_args()
 
 
@@ -80,6 +89,21 @@ def main():
 
     bots_to_test = filter(lambda bot: bot not in options.exclude, specified_bots)
 
+    if options.pytest:
+        excluded_bots = ['merels']
+        pytest_bots_to_test = sorted([bot for bot in bots_to_test if bot not in excluded_bots])
+        pytest_options = [
+            '-s',    # show output from tests; this hides the progress bar though
+            '-x',    # stop on first test failure
+            '--ff',  # runs last failure first
+        ]
+        pytest_options += (['-v'] if options.verbose else [])
+        os.chdir(bots_dir)
+        result = pytest.main(pytest_bots_to_test + pytest_options)
+        if result != 0:
+            sys.exit(1)
+        failures = False
+    else:
         # Codecov seems to work only when using loader.discover. It failed to
         # capture line executions for functions like loader.loadTestFromModule
         # or loader.loadTestFromNames.
@@ -98,10 +122,11 @@ def main():
         suite = unittest.TestSuite(test_suites)
         runner = unittest.TextTestRunner(verbosity=2)
         result = runner.run(suite)
-    if result.failures or result.errors:
+        failures = result.failures
+        if failures or result.errors:
             sys.exit(1)
 
-    if not result.failures and options.coverage:
+    if not failures and options.coverage:
         cov.stop()
         cov.data_suffix = False  # Disable suffix so that filename is .coverage
         cov.save()