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Tests

Tests module.

python_package_template_test

This file contains examples of how to write tests using pytest!

Some good practices for writting great Python tests:

Source: https://www.nerdwallet.com/blog/engineering/5-pytest-best-practices/

  • Prefer mocker over mock
  • Parametrize the same behavior, have different tests for different behaviors
  • Don’t modify fixture values in other fixtures
  • Prefer responses over mocking outbound HTTP requests
  • Prefer tmpdir over global test artifacts

TestGroup

A class with common parameters, param1 and param2.

Source code in tests/python_package_template_test.py 
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@pytest.mark.parametrize(
    ("param1", "param2"),
    [
        ("a", "b"),
        ("c", "d"),
    ],
)
class TestGroup:
    """A class with common parameters, `param1` and `param2`."""

    @pytest.fixture()
    def fixt(self: Self) -> int:
        """This fixture will only be available within the scope of TestGroup.

        Returns:
            int: A common value to be used by multiple tests

        """
        return 123

    def test_one(self: Self, param1: str, param2: str, fixt: int) -> None:
        """Run the first test using the fixture.

        Args:
            param1 (str): First parameter.
            param2 (str): Second parameter.
            fixt (int): Value from fixture.

        """
        print("\ntest_one", param1, param2, fixt)

fixt 

fixt()

This fixture will only be available within the scope of TestGroup.

Returns:

  • int ( int ) –

    A common value to be used by multiple tests

Source code in tests/python_package_template_test.py 
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@pytest.fixture()
def fixt(self: Self) -> int:
    """This fixture will only be available within the scope of TestGroup.

    Returns:
        int: A common value to be used by multiple tests

    """
    return 123

test_one 

test_one(param1, param2, fixt)

Run the first test using the fixture.

Parameters:

  • param1 (str) –

    First parameter.

  • param2 (str) –

    Second parameter.

  • fixt (int) –

    Value from fixture.

Source code in tests/python_package_template_test.py 
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def test_one(self: Self, param1: str, param2: str, fixt: int) -> None:
    """Run the first test using the fixture.

    Args:
        param1 (str): First parameter.
        param2 (str): Second parameter.
        fixt (int): Value from fixture.

    """
    print("\ntest_one", param1, param2, fixt)

test_divide_error 

test_divide_error(a, b, expected)

Check if divide returns correct Exceptions for known entries.

Issue raised by https://github.com/nullhack/python-project-template/issues/1337

Parameters:

  • a (float) –

    Dividend.

  • b (float) –

    Divisor.

  • expected (Exception) –

    expected Exception.

Source code in tests/python_package_template_test.py 
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@pytest.mark.parametrize(
    ("a", "b", "expected"),
    [
        (42, "b", TypeError),
        ("a", 42, TypeError),
        (42, 0, ZeroDivisionError),
    ],
)
def test_divide_error(
    a: str | float, b: str | float, expected: float | Exception
) -> None:
    """Check if divide returns correct Exceptions for known entries.

    Issue raised by https://github.com/nullhack/python-project-template/issues/1337

    Args:
        a (float): Dividend.
        b (float): Divisor.
        expected (Exception): expected Exception.

    """
    with pytest.raises(expected):
        m.Calculator.divide(a, b)

test_divide_ok 

test_divide_ok(a, b, expected)

Check if divide works for expected entries.

Parameters:

  • a (float) –

    Dividend.

  • b (float) –

    Divisor.

  • expected (float) –

    expected result.

Source code in tests/python_package_template_test.py 
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@pytest.mark.parametrize(
    ("a", "b", "expected"),
    [
        (1, 1, 1),
        (42, 1, 42),
        (84, 2, 42),
    ],
)
def test_divide_ok(a: float, b: float, expected: float) -> None:
    """Check if divide works for expected entries.

    Args:
        a (float): Dividend.
        b (float): Divisor.
        expected (float): expected result.

    """
    assert m.Calculator.divide(a, b) == expected