Part 12: Testing and Code Quality

_____ matters because it helps you catch bugs early, prove your code works, and make changes with more confidence.

Testing

A(n) _____ _____ checks one small piece of code, like a single function, by itself.

unit test

A(n) _____ _____ at a beginner level checks whether multiple parts of your code work correctly together.

integration test

The _____, _____, _____ pattern means you first set up the test data, then run the code, and then check the result.

Arrange, Act, Assert

_____ are the checks in a test that verify whether the actual result matches the expected result.

Assertions

Testing a(n) _____ _____ means checking that your code works correctly in the normal expected situation.

happy path

Testing _____ _____ means checking unusual, extreme, or boundary inputs that could still happen in real use.

edge cases

Testing _____ _____ means checking what your code does when something goes wrong or invalid input is provided.

failure cases

_____ means replacing a real dependency with a fake version so you can control how it behaves during a test.

Mocking

_____ are tools that watch whether a function was called, how many times it was called, and what arguments it received.

Spies

Testing _____ code means checking code that does not finish immediately, such as code that uses promises, timers, or API calls.

async

_____ tests clearly means giving each test a name that explains what is being tested and what result you expect.

Naming

Before you _____ a function, you should test it with normal input, edge cases, and bad input to make sure it behaves correctly.

trust

_____ is the process of automatically checking your code for style problems, possible mistakes, or rule violations.

Linting

_____ is the process of making your code look clean and consistent, such as spacing, indentation, and line breaks.

Formatting

_____ _____ means using variable, function, and class names that clearly describe what they do.

readable naming

_____ _____ are easier to understand, test, reuse, and debug because each one does less.

small functions

A(n) _____ _____ means a function, class, or file should have one main job or reason to change.

single responsibility

_____ stands for “Don’t Repeat Yourself,” which means you should avoid repeating the same logic in multiple places.

DRY

_____ stands for “Keep It Simple, Stupid,” which means you should prefer simpler solutions over unnecessarily complicated ones.

KISS

_____ _____ means different parts of your program should handle different jobs instead of mixing everything together.

separation of concerns

You should _____ code when it works but could be made clearer, cleaner, easier to maintain, or less repetitive without changing what it does.

refactor

When talking about tradeoffs in _____ _____, you should be able to explain why one solution may be simpler, faster, cleaner, or easier to maintain than another.

code quality