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unittest Testing Framework

Qualified supports the unittest unit testing framework.

Note

From Python 3.7, the solution module is no longer imported implicitly to avoid confusing error messages. Tests must use import solution from the solution module and optional preloaded code can be accessed using import preloaded.

Basic Example

Here is a minimal example of unit testing in Qualified's Python 3.7 environment (or more recent) by explicitly importing the solution and preloaded modules. For Project Code Challenges, these imports can be any module name in the workspace.

from unittest import TestCase

import preloaded # preloaded code you can provide the solution 
                 # and/or test module (omit if preloaded is empty)

import solution  # the candidate's solution

TestCase.maxDiff = None

class Test(TestCase):
    def test_add(self):
        "add two numbers"
        self.assertEqual(solution.add(2, 1), 3)
        
    def test_subtract(self):
        "subtract two numbers"
        self.assertEqual(solution.subtract(2, 1), 1)
        
    def test_division_by_zero(self):
        "divide by zero"
        self.assertRaises(ZeroDivisionError, solution.divide, 42, 0)

As demonstrated above, methods intended to be tested must begin with the prefix test. The Test class name is flexible. You can add multiple classes. Verbose test descriptions can be provided with a simple docstring.

If you're using Python versions older than 3.7 in our code runner, the solution and preloaded modules are implicitly imported into the testing module as from solution import *.

Visit unittest — Basic Example for a simple, platform-agnostic example of unittest.

Assertions

The crux of each test is a call to assertEqual() to check for an expected result; assertTrue() or assertFalse() to verify a condition; or assertRaises() to verify that a specific exception gets raised. These methods are used instead of the assert statement so the test runner can accumulate all test results and produce a report.

Setup and Tear Down

The setUp() and tearDown() methods allow you to execute code before and after each test method.

Similarly, you can use setUpClass() and tearDownClass() to run code before all tests run and after all tests complete, respectively.

Test Ordering

Unittest reorders test cases by default which can cause frustration for candidates and students when matching test case code with the output displayed on the runner. There are a variety of solutions to the problem which you can read about on this Stack Overflow thread, but the following approach should work for typical cases:

import inspect

class Test(unittest.TestCase):
    # ... test cases ...

test_src = inspect.getsource(Test)
unittest.TestLoader.sortTestMethodsUsing = lambda _, x, y: (
    test_src.index(f"def {x}") - test_src.index(f"def {y}")
)