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Diffstat (limited to 'nova/testing')
| -rw-r--r-- | nova/testing/README.rst | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/nova/testing/README.rst b/nova/testing/README.rst index 67fa33d1d..4c341b7ed 100644 --- a/nova/testing/README.rst +++ b/nova/testing/README.rst @@ -54,13 +54,33 @@ Writing Integration Tests TBD -Tests and assertRaises ----------------------- -When asserting that a test should raise an exception, test against the -most specific exception possible. An overly broad exception type (like -Exception) can mask errors in the unit test itself. +Tests and Exceptions +-------------------- +A properly written test asserts that particular behavior occurs. This can +be a success condition or a failure condition, including an exception. +When asserting that a particular exception is raised, the most specific +exception possible should be used. + +In particular, testing for Exception being raised is almost always a +mistake since it will match (almost) every exception, even those +unrelated to the exception intended to be tested. + +This applies to catching exceptions manually with a try/except block, +or using assertRaises(). Example:: self.assertRaises(exception.InstanceNotFound, db.instance_get_by_uuid, elevated, instance_uuid) + +If a stubbed function/method needs a generic exception for testing +purposes, test.TestingException is available. + +Example:: + + def stubbed_method(self): + raise test.TestingException() + self.stubs.Set(cls, 'inner_method', stubbed_method) + + obj = cls() + self.assertRaises(test.TestingException, obj.outer_method) |