Learn How to Auto-Grade

Auto-grading is a powerful tool that saves teachers time and provides students with feedback regarding the correctness of their solution before they submit it for a grade.

All of this auto-grading magic can be accomplished with unit testing -- test whether parts (units) of a students code work properly by asserting that they meet certain conditions (equal to a predetermined value, produce a result in a given range, etc.).

Assertions and Unit TestingPython ExamplesJava ExamplesRuby Examples

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Quick Start

New to Unit Testing? Let's do a brief review.

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Python - unittest

The basic building blocks of unit testing are test cases — single scenarios that must be set up and checked for correctness.

The simplest TestCase subclass will simply implement a test method (i.e. a method whose name starts with test) in order to perform specific testing code:

def test_default_case(self):
    # Your test case logic here (replace the example assertion below)
    # You may also rename this to any function in the form of 'test_your_test_name(self):'
    self.assertTrue(True)

Note that in order to test something, we use one of the assert*() methods provided by the TestCase base class. If the test fails, an exception will be raised with an explanatory message, and unittest will identify the test case as a failure. Any other exceptions will be treated as errors.

Tests can be numerous, and their set-up can be repetitive. Luckily, we can factor out set-up code by implementing a method called setUp(), which the testing framework will automatically call for every single test we run:

def setUp(self):
    # Setup code here (if required, replace the 'pass')
    pass

Similarly, we can provide a tearDown() method that tidies up after the test method has been run:

def tearDown(self):
    # Teardown code here (if required, replace the 'pass')
    pass

If setUp() succeeded, tearDown() will be run whether the test method succeeded or not.

Java - JUnit

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@Test
public void testDefaultCase() {
    // You may rename this method to better suit the purpose of your test case
    // Your test case logic here
}

@Before
public void setUp() {
    // Setup code here (if required)
}

@After
public void tearDown() {
    // Teardown code here (if required)
}

Created and curated by Joe Mazzone

Joe Mazzone, former Computer and Software Engineering instructor at William M. Davies, Jr. Career and Technical High School in Lincoln, Rhode Island.

Joe is now a Senior Product Manager/Product Development Lead at John Wiley & Sons, Inc., working on Coding Rooms and zyBooks.

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