avocado: Add fail_on_error decorator

Give to test writers the fail_on_error decorator, which
should turn any generic exception into an avocado
TestFail.

This is important for some tests that can raise
any exception during a complex operation, and any of those
exceptions can be considered a test failure.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/__init__.py

@@ -13,9 +13,10 @@
 # Author: Lucas Meneghel Rodrigues <lmr@redhat.com>
 
 
-__all__ = ['main', 'Test', 'VERSION']
+__all__ = ['main', 'Test', 'VERSION', 'fail_on_error']
 
 
 from avocado.core.job import main
 from avocado.core.test import Test
 from avocado.core.version import VERSION
+from avocado.core.exceptions import fail_on_error

avocado/core/exceptions.py

@@ -17,6 +17,29 @@ Exception classes, useful for tests, and other parts of the framework code.
 """
 
 
+def fail_on_error(fn):
+    """
+    Apply to any test you want to FAIL upon any exception raised.
+
+    Normally only TestFail called explicitly will mark an avocado test with the
+    FAIL state, but this decorator is provided as a convenience for people
+    that need a more relaxed behavior.
+
+    :param fn: Function that will be decorated
+    """
+    def new_fn(*args, **kwargs):
+        try:
+            return fn(*args, **kwargs)
+        except TestBaseException:
+            raise
+        except Exception, e:
+            raise TestFail(str(e))
+    new_fn.__name__ = fn.__name__
+    new_fn.__doc__ = fn.__doc__
+    new_fn.__dict__.update(fn.__dict__)
+    return new_fn
+
+
 class JobBaseException(Exception):
 
     """

examples/tests/fail_on_error.py

+#!/usr/bin/python
+
+import avocado
+
+
+class FailOnError(avocado.Test):
+
+    """
+    Test illustrating the behavior of the fail_on_error decorator.
+    """
+
+    @avocado.fail_on_error
+    def test(self):
+        """
+        This should end with FAIL.
+
+        Avocado tests should end with ERROR when a generic exception such as
+        ValueError is raised. The avocado.fail_on_error decorator allows you
+        to override this behavior, and turn your generic exceptions into
+        errors.
+        """
+        raise ValueError('This raises a ValueError and should end as a FAIL')
+
+if __name__ == "__main__":
+    avocado.main()

selftests/all/functional/avocado/basic_tests.py

@@ -126,6 +126,17 @@ class RunnerOperationTest(unittest.TestCase):
                                                                 result))
         self.assertIn('"status": "ERROR"', result.stdout)
 
+    def test_fail_on_error(self):
+        os.chdir(basedir)
+        cmd_line = ("./scripts/avocado run --sysinfo=off --job-results-dir %s "
+                    "--json - fail_on_error" % self.tmpdir)
+        result = process.run(cmd_line, ignore_status=True)
+        expected_rc = 1
+        self.assertEqual(result.exit_status, expected_rc,
+                         "Avocado did not return rc %d:\n%s" % (expected_rc,
+                                                                result))
+        self.assertIn('"status": "FAIL"', result.stdout)
+
     def test_runner_timeout(self):
         os.chdir(basedir)
         cmd_line = './scripts/avocado run --sysinfo=off --job-results-dir %s --xunit - timeouttest' % self.tmpdir