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.
Kotlin
Kotlin runs on the JVM and integrates seamlessly with the Java testing ecosystem.
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.
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.
Rust
Rust's built-in #[bench] attribute requires nightly and lacks statistical rigor.
Rust
cargo-nextest is a next-generation test runner for Rust that replaces cargo test with a process-per-test execution model, better terminal output, built-in retry logic, and significantly faster CI runs. It's a drop-in replacement — your existing tests work unchanged. Why nextest? cargo test runs
Kotlin
Android has two types of tests: unit tests (JVM, fast) and instrumented tests (run on a device or emulator, access Android APIs).
Rust
Rust ships with a built-in test framework. No extra dependencies, no configuration files — just annotate a function with #[test] and run cargo test.
Rust
Rust's borrow checker and type system make certain mocking patterns harder than in dynamic languages, but the mockall crate brings first-class mocking support to Rust's test ecosystem. This guide covers the practical patterns you'll reach for in real projects. Why Mock? Mocks replace
Flutter
Flutter golden tests capture a screenshot of a widget and compare it pixel-by-pixel against a reference image (the "golden file"). If the screenshot changes, the test fails. This catches visual regressions — layout shifts, color changes, font differences — that behavioral tests miss entirely. This guide covers writing