Software Testing Best Practices

What this best practices guide is

A practical guide to writing tests that catch real bugs and stay cheap to maintain. It covers choosing the right level for each test, unit test design, mocks and other test doubles, integration and end-to-end tests, flaky tests, coverage and mutation testing, and keeping the suite fast in CI. The advice is language agnostic, with examples in TypeScript and Python.

It has 8 chapters and 34 practices, each with why it matters, what to do and what to avoid. For developers and CS students.

Chapter by chapter

1. Choosing what to test and at which level (4 practices)

Every test has a cost and a level. This chapter covers the test pyramid, pushing tests to the lowest level that can catch the bug, and testing behaviour instead of implementation.

2. Writing good unit tests (5 practices)

A good unit test is short, readable, checks one behaviour and fails with a message that tells you what broke. This chapter covers structure, naming, table driven cases and edge cases.

3. Test doubles and mocking (4 practices)

Mocks, stubs and fakes let you test code without its slow or unpredictable dependencies. Used carelessly, they produce tests that pass while the real system is broken.

4. Integration tests (4 practices)

Integration tests check the places where your code meets something real: a database, a queue, the filesystem or another service. This chapter covers scope, real dependencies and test data.

5. End-to-end and browser tests (5 practices)

End-to-end tests give the most confidence and cost the most to run and keep. This chapter covers which journeys deserve them and how to write browser tests that do not break on every change.

6. Flaky tests (4 practices)

A flaky test passes and fails on the same code. This chapter covers why flakiness is so costly, its usual causes, and how to quarantine and fix flaky tests without hiding real bugs.

7. Coverage and test quality (4 practices)

Coverage tells you which code your tests ran, not whether they checked it. This chapter covers using coverage to find gaps, sensible targets and mutation testing.

8. Running tests in CI and keeping them fast (4 practices)

Tests only help if they run on every change and finish quickly. This chapter covers when to run which tests, speed, parallelism and treating test code as real code.

How it works on Sefism

The guide reads like a short course: a syllabus, then one chapter per page in a focused reader, with a quiz at the end of each chapter for members. The opening chapters are open to everyone. Adding it to your account uses credits, opens every chapter and keeps your progress.

Every claim is checked against the sources listed on the page (8 cited).