#10535: Enable silenced warnings in unittest by default

Lib/unittest/test/test_runner.py

@@ -1,5 +1,8 @@
 import io
+import os
+import sys
 import pickle
+import subprocess
 
 import unittest
 
@@ -144,6 +147,7 @@ class Test_TextTestRunner(unittest.TestCase):
         self.assertFalse(runner.failfast)
         self.assertFalse(runner.buffer)
         self.assertEqual(runner.verbosity, 1)
+        self.assertEqual(runner.warnings, None)
         self.assertTrue(runner.descriptions)
         self.assertEqual(runner.resultclass, unittest.TextTestResult)
 
@@ -244,3 +248,57 @@ class Test_TextTestRunner(unittest.TestCase):
 
         expectedresult = (runner.stream, DESCRIPTIONS, VERBOSITY)
         self.assertEqual(runner._makeResult(), expectedresult)
+
+    def test_warnings(self):
+        """
+        Check that warnings argument of TextTestRunner correctly affects the
+        behavior of the warnings.
+        """
+        # see #10535 and the _test_warnings file for more information
+
+        def get_parse_out_err(p):
+            return [b.splitlines() for b in p.communicate()]
+        opts = dict(stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                    cwd=os.path.dirname(__file__))
+        ae_msg = b'Please use assertEqual instead.'
+        at_msg = b'Please use assertTrue instead.'
+
+        # no args -> all the warnings are printed, unittest warnings only once
+        p = subprocess.Popen([sys.executable, '_test_warnings.py'], **opts)
+        out, err = get_parse_out_err(p)
+        self.assertEqual(err[-1], b'OK')
+        # check that the total number of warnings in the output is correct
+        self.assertEqual(len(out), 12)
+        # check that the numbers of the different kind of warnings is correct
+        for msg in [b'dw', b'iw', b'uw']:
+            self.assertEqual(out.count(msg), 3)
+        for msg in [ae_msg, at_msg, b'rw']:
+            self.assertEqual(out.count(msg), 1)
+
+        args_list = (
+            # passing 'ignore' as warnings arg -> no warnings
+            [sys.executable, '_test_warnings.py', 'ignore'],
+            # -W doesn't affect the result if the arg is passed
+            [sys.executable, '-Wa', '_test_warnings.py', 'ignore'],
+            # -W affects the result if the arg is not passed
+            [sys.executable, '-Wi', '_test_warnings.py']
+        )
+        # in all these cases no warnings are printed
+        for args in args_list:
+            p = subprocess.Popen(args, **opts)
+            out, err = get_parse_out_err(p)
+            self.assertEqual(err[-1], b'OK')
+            self.assertEqual(len(out), 0)
+
+
+        # passing 'always' as warnings arg -> all the warnings printed,
+        #                                     unittest warnings only once
+        p = subprocess.Popen([sys.executable, '_test_warnings.py', 'always'],
+                             **opts)
+        out, err = get_parse_out_err(p)
+        self.assertEqual(err[-1], b'OK')
+        self.assertEqual(len(out), 14)
+        for msg in [b'dw', b'iw', b'uw', b'rw']:
+            self.assertEqual(out.count(msg), 3)
+        for msg in [ae_msg, at_msg]:
+            self.assertEqual(out.count(msg), 1)