unittest: Exit with non-zero code on failures.

`unittest.main()` will now cause the process to exit with a non-zero
status code on test failure. This behaviour is assumed by the test
framework used in this repo (in `tools/ci.sh`), is what happens when
using the unittest-discover module, and is what CPython does.

Removing `unittest/tests/exception.py` as this test always fails (by
design). This functionality (a bare function being used as a test raises
an error that is not a subclass of `AssertionError`) had a test added in
the previous commit (`test_basics.Basics.test_bare_function__error`).

Signed-off-by: Greg Darke <micropython@me.tsukasa.au>

Author: tsukasa-au

python-stdlib/unittest/tests/exception.py

@@ -593,4 +593,7 @@ def main(module="__main__", testRunner=None):
         module = __import__(module)
     suite = TestSuite(module.__name__)
     suite._load_module(module)
-    return testRunner.run(suite)
+    result = testRunner.run(suite)
+    if not result.wasSuccessful():
+        sys.exit(result.failuresNum + result.errorsNum)
+    return result

python-stdlib/unittest/unittest/__init__.py

@@ -63,7 +63,6 @@ function ci_package_tests_run {
         python-stdlib/os-path/test_path.py \
         python-stdlib/pickle/test_pickle.py \
         python-stdlib/string/test_translate.py \
-        python-stdlib/unittest/tests/exception.py \
         unix-ffi/gettext/test_gettext.py \
         unix-ffi/pwd/test_getpwnam.py \
         unix-ffi/re/test_re.py \