test_suite.py in Python

A pytest file as it looks in a real project: fixtures, parametrize, marks.

"""Run me with: pytest test_suite.py -v"""

import pytest

# ---- the code under test ---------------------------------------------


class Scorer:
    def __init__(self, target_tpm: int = 90):
        if target_tpm <= 0:
            raise ValueError("target must be positive")
        self.target_tpm = target_tpm
        self.history: list[int] = []

    def stars(self, tpm: float, accuracy: float) -> int:
        if accuracy < 0 or accuracy > 100:
            raise ValueError(f"accuracy out of range: {accuracy}")
        earned = 1
        if accuracy >= 95:
            earned = 2
        if accuracy >= 98 and tpm >= self.target_tpm:
            earned = 3
        self.history.append(earned)
        return earned

    @property
    def best(self) -> int:
        return max(self.history, default=0)


# ---- the tests -------------------------------------------------------


@pytest.fixture
def scorer():
    return Scorer(target_tpm=90)


@pytest.mark.parametrize("tpm,accuracy,expected", [
    (60.0, 90.0, 1),
    (60.0, 96.0, 2),
    (95.0, 99.0, 3),
    (80.0, 99.0, 2),
])
def test_stars_by_tier(scorer, tpm, accuracy, expected):
    assert scorer.stars(tpm, accuracy) == expected


def test_history_and_best(scorer):
    scorer.stars(95.0, 99.0)
    scorer.stars(50.0, 80.0)
    assert scorer.history == [3, 1]
    assert scorer.best == 3


def test_empty_history_has_no_best(scorer):
    assert scorer.best == 0


@pytest.mark.parametrize("accuracy", [-1.0, 101.0])
def test_rejects_impossible_accuracy(scorer, accuracy):
    with pytest.raises(ValueError, match="out of range"):
        scorer.stars(90.0, accuracy)


def test_rejects_a_zero_target():
    with pytest.raises(ValueError, match="positive"):
        Scorer(target_tpm=0)


def test_target_is_respected(monkeypatch):
    strict = Scorer(target_tpm=200)
    assert strict.stars(150.0, 99.0) == 2


@pytest.mark.parametrize("target", [1, 90, 500])
def test_any_positive_target_builds(target):
    assert Scorer(target).target_tpm == target

How it works

1. The module under test sits at the top, so the file is self-contained.
2. Fixtures build the objects; parametrize covers the cases.
3. Running pytest on this file exercises every path below.

Keywords and builtins used here

• Scorer
• assert
• best
• class
• def
• float
• if
• int
• list
• max
• raise
• return
• scorer
• self
• stars
• test_any_positive_target_builds
• test_empty_history_has_no_best
• test_history_and_best
• test_rejects_a_zero_target
• test_rejects_impossible_accuracy
• test_stars_by_tier
• test_target_is_respected
• with

The run, in numbers

Lines

78

Characters to type

1797

Tokens

408

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 223 seconds.

Type this snippet

Step 1 of 1 in Encore, step 9 of 9 in Testing with pytest.

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