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Repovive

Testing Data Code - Python for Data Engineering | Data Engineer Interview Prep | Repovive

Repovive.

Data Engineer Interview Prep16 sections · 140 units8h total

Open in Course

Testing Data Code

Reliable pipelines

Test your Python data code:

Unit tests: Test transformations with small sample data.

def test_clean_nulls():
    input_df = pd.DataFrame({'a': [1, None, 3]})
    result = clean_nulls(input_df)
    assert result['a'].isna().sum() == 0

Integration tests: Test against real (dev) databases.

Contract tests: Verify output matches expected schema.

Fixtures: Create reusable test data.

@pytest.fixture
def sample_orders():
    return pd.DataFrame({
        'order_id': [1, 2, 3],
        'amount': [100, 200, 150]
    })

Run tests in CI. Block merges on test failure.