Software Testing and Testing Automation with Python

Coverage

Coverage tells us how much of our code is tested by the test suite. It is easy to forget to test a branch, code path, or function/method when following the “write it then test it” model (called “debug later” by James Grenning). There is an alternative method of “Test Driven Development” or TDD for short, but development strategies are really beyond the scope of what we’re trying to do here. Even when following the TDD methodology, a coverage check helps keep you honest!

To check coverage we’ll be using pytest-cov. It’s simple to run from the command line.

• Open a terminal (or Anaconda Prompt)
• Navigate to the root directory of the repository.
• Run pytest --cov-report term-missing --cov=meteogram tests/ from the meteogram directory.

Exercise 4

• Run a coverage check on our library. What holes do we have? Are there any you can repair with what we've learned so far? Try writing some tests to increase the coverage. You haven't learned techniques to test everything yet, but increase coverage where you can.

Solution

def test_current_utc_time():
    """Verify operation of utctime fetching (ignoring microseconds)."""
    # Setup - none necessary

    # Exercise
    result = meteogram.current_utc_time()

    # Verify
    truth = datetime.datetime.utcnow()
    assert result.replace(microsecond=0) == truth.replace(microsecond=0)

    # Cleanup - none necessary


def test_potential_temperature():
    """Test potential temperature calculation with known result."""
    # Setup - none necessary

    # Exercise
    result = meteogram.potential_temperature(800, 273)

    # Verify
    truth = 290.96
    assert_almost_equal(result, truth, 2)

    # Cleanup - none necessary


def test_exner_function():
    """Test exner function calculation."""
    # Setup - none necessary

    # Exercise
    result = meteogram.exner_function(500)

    # Verify
    truth = 0.8203833
    assert_almost_equal(result, truth, 4)

    # Cleanup - none necessary

Bonus

Add the --flake8 flag and cleanup any errors seen there.

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