Assert Statement

The assert statement is used to verify that a condition is True. If the condition is False, the test fails. Pytest enhances the basic assert by providing detailed output when the assertion fails, making it easier to understand what went wrong.

Simple Assertions:

Check that the condition is evaluated as True. If it is evaluated as False, Pytest raises an AssertionError and marks the test as failed.

In the next example, word.isupper() should return True if word is in uppercase. If not, the test fails.

Comparative Assertions:

To verify that the result of an operation (actual) matches the expected value.

Here, the add function is tested to ensure it correctly adds two numbers. The message after the comma provides additional context if the test fails.

Assertions with Detailed Feedback:

To provide a custom error message that displays when the assertion fails, offering more insight into the issue.

This assertion checks whether the multiply function returns 10 when multiplying 2 and 5. The custom message clarifies the expected outcome versus the actual result if the test fails.

Assertions for Exceptions:

To confirm that a certain exception is raised by a block of code.

This test ensures that dividing by zero raises a ZeroDivisionError. It’s essential for testing error handling in your code.

Advanced Assertions:

Use assertions to check more complex conditions, such as contents of lists, dictionaries, or more nuanced states in your application.

This test checks for the presence of an item in a list, providing clear feedback if the item is missing.