[python] Running a single test from unittest.TestCase via the command line

Inspired by yarkee, I combined it with some of the code I already got. You can also call this from another script, just by calling the function run_unit_tests() without requiring to use the command line, or just call it from the command line with python3 my_test_file.py.

import my_test_file
my_test_file.run_unit_tests()

Sadly this only works for Python 3.3 or above:

import unittest

class LineBalancingUnitTests(unittest.TestCase):

    @classmethod
    def setUp(self):
        self.maxDiff = None

    def test_it_is_sunny(self):
        self.assertTrue("a" == "a")

    def test_it_is_hot(self):
        self.assertTrue("a" != "b")

Runner code:

#! /usr/bin/env python3
# -*- coding: utf-8 -*-
import unittest
from .somewhere import LineBalancingUnitTests

def create_suite(classes, unit_tests_to_run):
    suite = unittest.TestSuite()
    unit_tests_to_run_count = len( unit_tests_to_run )

    for _class in classes:
        _object = _class()
        for function_name in dir( _object ):
            if function_name.lower().startswith( "test" ):
                if unit_tests_to_run_count > 0 \
                        and function_name not in unit_tests_to_run:
                    continue
                suite.addTest( _class( function_name ) )
    return suite

def run_unit_tests():
    runner = unittest.TextTestRunner()
    classes =  [
        LineBalancingUnitTests,
    ]

    # Comment all the tests names on this list, to run all Unit Tests
    unit_tests_to_run =  [
        "test_it_is_sunny",
        # "test_it_is_hot",
    ]
    runner.run( create_suite( classes, unit_tests_to_run ) )

if __name__ == "__main__":
    print( "\n\n" )
    run_unit_tests()

Editing the code a little, you can pass an array with all unit tests you would like to call:

...
def run_unit_tests(unit_tests_to_run):
    runner = unittest.TextTestRunner()

    classes = \
    [
        LineBalancingUnitTests,
    ]

    runner.run( suite( classes, unit_tests_to_run ) )
...

And another file:

import my_test_file

# Comment all the tests names on this list, to run all unit tests
unit_tests_to_run = \
[
    "test_it_is_sunny",
    # "test_it_is_hot",
]

my_test_file.run_unit_tests( unit_tests_to_run )

Alternatively, you can use load_tests Protocol and define the following method in your test module/file:

def load_tests(loader, standard_tests, pattern):
    suite = unittest.TestSuite()

    # To add a single test from this file
    suite.addTest( LineBalancingUnitTests( 'test_it_is_sunny' ) )

    # To add a single test class from this file
    suite.addTests( unittest.TestLoader().loadTestsFromTestCase( LineBalancingUnitTests ) )

    return suite

If you want to limit the execution to one single test file, you just need to set the test discovery pattern to the only file where you defined the load_tests() function.

#! /usr/bin/env python3
# -*- coding: utf-8 -*-
import os
import sys
import unittest

test_pattern = 'mytest/module/name.py'
PACKAGE_ROOT_DIRECTORY = os.path.dirname( os.path.realpath( __file__ ) )

loader = unittest.TestLoader()
start_dir = os.path.join( PACKAGE_ROOT_DIRECTORY, 'testing' )

suite = loader.discover( start_dir, test_pattern )
runner = unittest.TextTestRunner( verbosity=2 )
results = runner.run( suite )

print( "results: %s" % results )
print( "results.wasSuccessful: %s" % results.wasSuccessful() )

sys.exit( not results.wasSuccessful() )

References:

1. Problem with sys.argv[1] when unittest module is in a script
2. Is there a way to loop through and execute all of the functions in a Python class?
3. looping over all member variables of a class in python

Alternatively, to the last main program example, I came up with the following variation after reading the unittest.main() method implementation:

1. https://github.com/python/cpython/blob/master/Lib/unittest/main.py#L65

#! /usr/bin/env python3
# -*- coding: utf-8 -*-

import os
import sys
import unittest

PACKAGE_ROOT_DIRECTORY = os.path.dirname( os.path.realpath( __file__ ) )
start_dir = os.path.join( PACKAGE_ROOT_DIRECTORY, 'testing' )

from testing_package import main_unit_tests_module
testNames = ["TestCaseClassName.test_nameHelloWorld"]

loader = unittest.TestLoader()
suite = loader.loadTestsFromNames( testNames, main_unit_tests_module )

runner = unittest.TextTestRunner(verbosity=2)
results = runner.run( suite )

print( "results: %s" % results )
print( "results.wasSuccessful: %s" % results.wasSuccessful() )
sys.exit( not results.wasSuccessful() )