Swift
Swift's built-in testing framework is XCTest, shipped with Xcode and available on all Apple platforms. Every Swift project created in Xcode includes an XCTest target by default. This guide covers how to write, organize, and run effective unit tests with XCTest. Project Setup When you create a new
Swift
Swift's structured concurrency model — async/await, actors, Task, and MainActor — requires specific testing patterns. The good news: Xcode 14+ makes async testing natural, and the actor model gives you clear isolation boundaries that map well to test setup. Async Test Methods Any XCTestCase method can be async (and
Kotlin
Spring Boot's test support is comprehensive, and Kotlin's concise syntax makes test setup significantly less verbose than the equivalent Java. This guide covers the main testing strategies for Spring Boot applications written in Kotlin. Dependencies // build.gradle.kts dependencies { testImplementation("org.springframework.boot:spring-boot-starter-test"
Swift
Swift doesn't have a reflection-based mocking framework like Java's Mockito — the language's static type system makes runtime proxy generation impractical. Instead, Swift mocking relies on protocols and dependency injection. The approach is more explicit but also more type-safe and faster at runtime. The Foundation:
Kotlin
Testing asynchronous Kotlin code used to require Thread.sleep and other workarounds. The kotlinx-coroutines-test library provides proper tools: virtual time, controlled dispatchers, and runTest — which makes async tests run synchronously without any thread juggling. Dependencies // build.gradle.kts testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.8.1") testImplementation("
Swift
Quick and Nimble are the most popular BDD testing libraries for Swift. Quick provides a describe/it DSL for organizing tests; Nimble provides expressive matchers. Together they make test intent clearer than raw XCTest and scale better for complex domain logic. Installation Swift Package Manager // Package.swift or Xcode Package
Kotlin
MockK is the go-to mocking library for Kotlin. Unlike Mockito (which was designed for Java), MockK understands Kotlin's type system — it handles data class, object, companion object, extension functions, coroutines, and final classes without workarounds. Installation // build.gradle.kts testImplementation("io.mockk:mockk:1.13.12"
Kotlin
Kotest is a pure-Kotlin testing framework that goes beyond JUnit 5's Java roots. It offers multiple specification styles, a rich matcher library, built-in property testing, and first-class coroutine support. If you want test code that reads like idiomatic Kotlin, Kotest is worth learning. Installation // build.gradle.kts dependencies
Kotlin
Kotlin runs on the JVM and integrates seamlessly with the Java testing ecosystem. JUnit 5 is the standard choice for Kotlin projects, but Kotlin's language features — named parameters, extension functions, infix notation, and data classes — enable more expressive test code than Java allows. This guide covers how to
Swift
XCUITest is Apple's framework for automating iOS UI interactions. Tests launch the app in a simulator or on a real device, interact with it like a user would, and assert on what appears on screen. Unlike unit tests, UI tests can catch integration issues — broken navigation, missing screens,
Rust
Standard Rust tests don't support parameterized test cases or reusable fixtures out of the box. The rstest crate fills that gap with #[case], #[fixture], #[values], and matrix test generation — all integrating cleanly with cargo test. Installation [dev-dependencies] rstest = "0.23" Copy #[case]: Parameterized Test Cases Without
Rust
Example-based tests check specific cases you've thought of. Property-based tests let the framework generate hundreds of random inputs and find cases you haven't thought of. For Rust, the proptest crate brings property-based testing with automatic failure shrinking into the standard cargo test workflow. What Is Property-Based