How to stop all tests from inside a test or setUp using unittest?

Question

I'm extending the python 2.7 unittest framework to do some function testing. One of the things I would like to do is to stop all the tests from running inside of a test, and inside of a setUpClass() method. Sometimes if a test fails, the program is so broken it is no longer of any use to keep testing, so I want to stop the tests from running.

I noticed that a TestResult has a shouldStop attribute, and a stop() method, but I'm not sure how to get access to that inside of a test.

Does anyone have any ideas? Is there a better way?

Answer 1

Here's another answer I came up with after a while:

First, I added a new exception:

class StopTests(Exception):
"""
Raise this exception in a test to stop the test run.

"""
    pass

then I added a new assert to my child test class:

def assertStopTestsIfFalse(self, statement, reason=''):
    try:
        assert statement            
    except AssertionError:
        result.addFailure(self, sys.exc_info())

and last I overrode the run function to include this right below the testMethod() call:

except StopTests:
    result.addFailure(self, sys.exc_info())
    result.stop()

I like this better since any test now has the ability to stop all the tests, and there is no cpython-specific code.

Answer 2

In case you are interested, here is a simple example how you could make a decision yourself about exiting a test suite cleanly with py.test:

# content of test_module.py
import pytest
counter = 0
def setup_function(func):
    global counter
    counter += 1
    if counter >=3:
        pytest.exit("decided to stop the test run")

def test_one():
    pass
def test_two():
    pass
def test_three():
    pass

and if you run this you get:

$ pytest test_module.py 
============== test session starts =================
platform linux2 -- Python 2.6.5 -- pytest-1.4.0a1
test path 1: test_module.py

test_module.py ..

!!!! Exit: decided to stop the test run !!!!!!!!!!!!
============= 2 passed in 0.08 seconds =============

You can also put the py.test.exit() call inside a test or into a project-specific plugin.

Sidenote: py.test natively supports py.test --maxfail=NUM to implement stopping after NUM failures.

Sidenote2: py.test has only limited support for running tests in the traditional unittest.TestCase style.

Answer 3

Currently, you can only stop the tests at the suite level. Once you are in a TestCase, the stop() method for the TestResult is not used when iterating through the tests.

Somewhat related to your question, if you are using python 2.7, you can use the -f/--failfast flag when calling your test with python -m unittest. This will stop the test at the first failure.

See 25.3.2.1. failfast, catch and buffer command line options

You can also consider using Nose to run your tests and use the -x, --stop flag to stop the test early.

Answer 4

In the test loop of unittest.TestSuite, there is a break condition at the start:

class TestSuite(BaseTestSuite):

    def run(self, result, debug=False):
        topLevel = False
        if getattr(result, '_testRunEntered', False) is False:
            result._testRunEntered = topLevel = True

        for test in self:
            if result.shouldStop:
                break

So I am using a custom test suite like this:

class CustomTestSuite(unittest.TestSuite):
    """ This variant registers the test result object with all ScriptedTests,
        so that a failed Loign test can abort the test suite by setting result.shouldStop
        to True
    """
    def run(self, result, debug=False):
        for test in self._tests:
            test.result = result

        return super(CustomTestSuite, self).run(result, debug)

with a custom test result class like this:

class CustomTestResult(TextTestResult):
    def __init__(self, stream, descriptions, verbosity):
        super(CustomTestResult, self).__init__(stream, descriptions, verbosity)
        self.verbosity = verbosity
        self.shouldStop = False

and my test classes are like:

class ScriptedTest(unittest.TestCase):
    def __init__(self, environment, test_cfg, module, test):
        super(ScriptedTest, self).__init__()
        self.result = None

Under certain conditions, I then abort the test suite; for example, the test suite starts with a login, and if that fails, I do not have to try the rest:

    try:
        test_case.execute_script(test_command_list)
    except AssertionError as e:
        if test_case.module == 'session' and test_case.test == 'Login':
            test_case.result.shouldStop = True
            raise TestFatal('Login failed, aborting test.')
        else:
            raise sys.exc_info()

Then I use the test suite in the following way:

    suite = CustomTestSuite()

    self.add_tests(suite)

    result = unittest.TextTestRunner(verbosity=self.environment.verbosity, stream=UnitTestLoggerStream(self.logger),
                                     resultclass=CustomTestResult).run(suite)

I'm not sure if there is a better way to do it, but it behaves correctly for my tests.

Answer 5

Though you won't get the usual test reports of the tests run so far, a very easy way to stop the test run from within a TestCase method is simply to raise KeyboardInterrupt inside the method.

You can see how only KeyboardInterrupt is allowed to bubble up inside unittest's test runner by looking at CPython's code here inside testPartExecutor().

Answer 6

The OP was about python 2.7. Skip ahead a decade, and for python 3.1 and above, the way to skip tests in python unittest has had an upgrade, but the documentation could use some clarification (IMHO):

The documentation covers the following:

• Skip All tests after first failure: use failfast (only useful if you really don't want to continue any further tests at all, including in other unrelated TestCase classes)
• Skip All tests in a TestCase class: decorate class with @unittest.skip(), etc.
• Skip a single method within a TestCase: decorate method with @unittest.skip(), etc.
• Conditionally skip a method or a class: decorate with @unittest.skipIf() or @unittest.skipUnless() etc.
• Conditionally skip a method, but not until something within that method runs: use self.skipTest() inside the method (this will skip that method, and ONLY that method, not subsequent methods)

The documentation does not cover the following (as of this writing):

1. Skip all tests within a TestCase class if a condition is met inside the setUpClass method: solution from this post raise unittest.SkipTest("skip all tests in this class") (there may be another way, but I'm unaware)
2. Skip all subsequent test methods in a TestCase class after a condition is met in one of the first tests, but still continue to test other unrelated TestCase classes. For this, I propose the following solution...

This solution assumes that you encounter the "bad state" in the middle of a test method, and which could only be noticed in a test method ONLY (i.e., it is not something that could have been determined in the setUpClass method, for whatever reason). Indeed the setUpClass method is the best location for determining whether to proceed if the initial conditions aren't right, but sometimes (as I've encountered) you just don't know until you run some test method. This solution assumes that test methods are in alphabetical order and that subsequent tests methods that you don't want to run after encountering the "bad" state follow alphabetically.

import unittest

class SkipMethodsConditionally(unittest.TestCase):

    @classmethod
    def setUpClass(cls):
        #this class variable maintains whether or not test methods should continue
        cls.should_continue = True
        #this class variable represents the state of your system. Replace with function of your own
        cls.some_bad_condition = False

    def setUp(self) -> None:
        """setUp runs before every single test method in this class"""
        if not self.__class__.should_continue:
            self.skipTest("no reason to go on.")

    def test_1_fail(self):
        #Do some work here. Let's assume you encounter a "bad state,"" that could 
        #only be noticed in this first test method only, (i.e., it's not something that
        #can be placed in the setUpClass method, for whatever reason)
        self.__class__.some_bad_condition = True

        if self.__class__.some_bad_condition:
            self.__class__.should_continue = False

        self.assertTrue(False,"this test should fail, rendering the rest of the tests irrelevant")

    def test_2_pass(self):
        self.assertFalse(self.__class__.some_bad_condition,"this test would pass normally if run, but should be skipped, because it would fail")

The above test will yield the following output:

test_1_fail (__main__.SkipMethodsConditionally) ... FAIL
test_2_pass (__main__.SkipMethodsConditionally) ... skipped 'no reason to go on.'
----------------------------------------------------------------------
Ran 2 tests in 0.001s

FAILED (failures=1, skipped=1)

Answer 7

I looked at the TestCase class and decided to subclass it. The class just overrides run(). I copied the method and starting at line 318 in the original class added this:

# this is CPython specific. Jython and IronPython may do this differently
if testMethod.func_code.co_argcount == 2:
    testMethod(result)
else:
    testMethod()

It has some CPython specific code in there to tell if the test method can accept another parameter, but since I'm using CPython everywhere, this isn't an issue for me.

Answer 8

Use:

if condition: 
   return 'pass'