Writing Simple Automated Tests
Manual testing gets tedious fast. Every time you change your code, you'd need to run through all your test cases by hand. Automated tests solve this by letting you verify your code works with a single command.
Think of automated tests as a safety net. They catch bugs before your users do, and they give you confidence to make changes without breaking things.
The Arrange-Act-Assert Pattern
Most tests follow a simple three-step structure:
Arrange — Set up the conditions for your test. Create test data, configure mocks, prepare inputs.
Act — Call the code you're testing. Run the function or method with your prepared inputs.
Assert — Check the results. Verify the output matches what you expected.
def test_add_numbers():
# Arrange
a = 5
b = 3
# Act
result = add(a, b)
# Assert
assert result == 8
Testing Frameworks
Different languages have different testing tools. For Python, pytest is the most popular choice. For JavaScript, Jest handles most testing needs.
These frameworks provide helpful features like test discovery (automatically finding your tests), assertions (checking results), and mocking (faking external dependencies).
Running Tests
You can run tests from the command line:
Most code editors also integrate with testing frameworks, letting you run tests with a click.
AI-Generated Tests
AI excels at generating test code. Give it your function and describe what scenarios to test:
Write pytest tests for my stock price fetcher function:
[paste function]
Include tests for:
- Valid stock symbol returns correct data structure
- Invalid symbol raises StockNotFoundError
- Network error is handled gracefully
- Missing API key raises helpful error
Use mocking for API calls so tests don't need network.
The AI will generate tests with proper mocking so your tests run fast without making real API calls.
Start Small
You don't need 100% test coverage. Start by testing the most important functions — the ones that would cause the most problems if they broke. Add more tests as you go.