Fixtures in Python

A fixture builds what a test needs, and tears it down afterwards.

import pytest


class Session:
    def __init__(self):
        self.runs = []
        self.closed = False

    def record(self, tpm):
        self.runs.append(tpm)

    def close(self):
        self.closed = True


@pytest.fixture
def session():
    made = Session()
    yield made
    made.close()


@pytest.fixture(scope="module")
def target():
    return 90


def test_records_runs(session, target):
    session.record(104)
    assert session.runs == [104]
    assert session.runs[0] > target

How it works

1. Requesting it by name is how a test asks for it.
2. A yield fixture cleans up after the test returns.
3. scope decides how often it is rebuilt.

Keywords and builtins used here

• Session
• assert
• class
• close
• def
• record
• return
• self
• session
• target
• test_records_runs
• yield

The run, in numbers

Lines

31

Characters to type

423

Tokens

117

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 67 seconds.

Type this snippet

Step 1 of 2 in Fixtures, step 4 of 9 in Testing with pytest.

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