Unit Tests

Updated May 19, 2023 ·

Testing in Machine Learning

Before deploying a model, testing ensures it works as expected and handles real-world scenarios correctly.

• Testing

  • Verifies that the model runs without errors
  • Ensures predictions are accurate and fast

• Unit Tests

  • Detect errors before deployment
  • Check specific parts of the model’s behavior
  • Run automatically during development

Writing Unit Tests

Python's unittest library helps define and run tests for models.

To create a test case, we can first subclass unittest.TestCase, then add test methods that start with test_. Use assertions to check expected behavior.

import unittest

class TestModelInference(unittest.TestCase):

    def setUp(self):
        self.model = fitted_model
        self.X_test = X_test

    def test_prediction_output_shape(self):
        y_pred = self.model.predict(self.X_testt)
        self.assertEqual(y_pred.shape[0], self.X_test.shape[0])

if __name__  == '__main__'
    unittest.main()

We can also use other built-in methods like assertIn() to verify that input values fall within a valid range, ensuring data integrity.

def test_input_values(self):
    print("Running test_input_values test case")
    for row in X_test:  
        for value in row:
            self.assertIn(value, range(0, 501))  

Key Considerations

Key Considerations

Writing unit tests helps catch errors early and ensures models work as expected.

• Running Unit Tests

  • Run tests after every change
  • Ensure new functionality is covered

• Avoiding Redundant Tests

  • Don’t test well-established library functions
  • Focus on critical features

• Benefits of Testing

  • Prevents errors in production
  • Increases confidence in model updates

Test-Driven Development

Test-Driven Development (TDD) ensures code reliability by writing tests before implementation.

• Write Tests First

  • Define expected behavior before coding
  • Guides development and prevents unexpected issues

• Iterate and Improve

  • Refactor code while keeping tests intact
  • Ensures long-term stability and maintainability