Testing strategy
Build a practical understanding of testing strategy from the underlying principles.
QUALITY · 18 ARTICLES
Testing & Code Quality
Reliable code is code you can change with confidence. Connect testing strategy, test doubles, code smells, and legacy improvement to everyday development.
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What this topic covers
TDD and test doubles
Build a practical understanding of tdd and test doubles from the underlying principles.
Code smells
Build a practical understanding of code smells from the underlying principles.
Refactoring
Build a practical understanding of refactoring from the underlying principles.
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New here? Start with these
A guided path from fundamentals to the next step.
XCTest Basics: Write Your First Test with Given-When-Then (Beginner's Guide)
In iOS development, you may keep putting off writing test code. Once you open XCTest, it can be hard to know where to start.
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TDD: The Red-Green-Refactor Cycle in Practice
"Write tests first? There isn't even any code yet—what would I test?"
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[Code Smell #1] Why Is Spaghetti Code Spaghetti?
Spaghetti code refers not to length or messiness, but to control flow. This article traces why spaghetti remained after Dijkstra’s 1968 letter against goto, and how to measure it with cyclomatic complexity.
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[Code Smell #5] Shotgun Surgery vs Divergent Change
Shotgun Surgery is a smell where one change is scattered across multiple files, while Divergent Change is its mirror image: one file changes for multiple reasons. This article explains how to measure and distinguish these opposite smells using commit history.
Read article[Code Smell #4] God Object: A Complete Guide
A God Object is a class that keeps absorbing surrounding responsibilities and data as it grows, becoming the file that changes and conflicts most often on a team. This guide covers the signals of growth, the extraction order, and two ways splitting it can fail.
Read article[Code Smell #3] Ravioli code: code whose flow nobody understands
Every function is five lines long and has one responsibility, yet nobody can explain what happens when a button is pressed. This article covers why decomposition goes too far, the cost revealed by jump counts, and how to recover the flow.
Read article[Code Smell #2] Lasagna Code: Why One Field Means Fixing Seven Files
Lasagna code is code where adding one field requires changing seven files despite neatly separated layers. This article summarizes why layers multiply, where they cost you, and when to keep or remove them.
Read articleXcode Test Plans: A Complete Guide to Running Tests by Configuration
Test Plans manage the tests to run and their execution conditions in .xctestplan files. This guide covers why schemes alone are insufficient, test selection, configurations, coverage, execution order, repetition, and xcodebuild integration.
Read articleThe Trap of 100% Code Coverage: What Percentage Is Right?
100% code coverage does not mean bug-free code. This article summarizes the practical 70–80% guideline and how to identify untested branches that matter more than the number.
Read articleAdding Tests to Legacy Code: What to Do Before Refactoring
For legacy code, characterization tests that lock in current behavior come before refactoring. This guide lays out the practical sequence for using seams to isolate code that cannot be tested because of dependencies.
Read articleHow to test asynchronous Swift code with async/await
In Swift 5.5 and later, declare test functions as async, await the result, and then verify it. This guide also covers error validation, testing legacy callback APIs, and when expectations are still needed.
Read articleSwift Testing: Apple’s New Standard Replacing XCTest (Quick Overview)
When writing test code for iOS development, XCTest can start to feel restrictive.
Read articleWhat Makes a Good Unit Test: A Complete Guide to the 5 FIRST Principles
Have you ever written tons of test code, only to miss the actual bugs—and watch tests break everywhere whenever you fix a feature?
Read articleUnit vs. integration vs. UI tests: the test pyramid explained at a glance
There’s a wall every developer eventually runs into.
Read articleTest Doubles Explained: Mock, Stub, Spy, and Fake (Examples & Table)
There’s a wall every developer eventually hits when writing test code.
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