fixtures.md

Fixtures

Sometimes you need to prepare test data (load files, create objects etc.). If you want to prepare the same data for multiple tests, you can use a fixture.

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Exercise 1: A module for test data

Create a new module conftest.py in the same directory as your tests. There, add a function that loads the file data/mobydick_summary.txt:

Place the decorator @pytest.fixture on top of it:

:::python3
import pytest

@pytest.fixture
def text_summary():
    return open(...).read()

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Exercise 2: Using the fixture

Now create a module test_corpus.py with a function that uses the fixture:

:::python3
def test_short_sample(text_summary):
    assert count_words(text_summary) == 77

Execute the module with pytest. Note that you do not need to import conftest. Pytest does that automatically.

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Exercise 3: Create more fixtures

Create a fixture for the full text of the book mobydick_full.txt as well.

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Exercise 4: Fixtures from fixtures

Create a fixture in conftest.py that prepares a dictionary with word counts using the word_counter.count_words_dict() function.

:::python3
from word_counter import count_words_dict

@pytest.fixture
def count_dict(text_summary):
	return ...

Write a simple test that makes sure the dictionary is not empty.