SwiftCheck
SwiftCheck is a free, MIT-licensed property-testing library for Swift developers.
What SwiftCheck is
SwiftCheck is a free, MIT-licensed property-testing library for Swift developers. Tests use the `forAll` quantifier to express properties that should hold across generated inputs, with values conforming to `Testable`. SwiftCheck implements `Arbitrary` for most Swift Standard Library types, and custom types can participate by defining generation and shrinking behavior. When a generated case fails, shrinking reduces the data toward a minimal counterexample. Generator combinators include `suchThat`, `fromElements`, `choose`, and `frequency`. Properties can be combined with conjunction and labels, and preconditions can discard inputs that do not apply. The README demonstrates properties inside an `XCTestCase` test class. Installation routes include Swift Package Manager, Carthage, CocoaPods, or adding the Xcode project as a framework dependency. Listed requirements are OS X 10.9+ and iOS 7.0+. The project links issue tracking and contribution guidance.
Good
- Free and MIT licensed
- Automatic random input generation
- Shrinks failures toward minimal counterexamples
- Supports custom generators and combinators
- Works with XCTest and several installation methods
Watch out
- Listed requirements include older OS X and iOS versions
- Swift-focused library
- Repository does not state a support service
Who it suits
It suits Swift developers who want QuickCheck-style property testing with XCTest. It is useful when generated inputs and reduced failing cases fit a project’s testing approach.
Verdict
SwiftCheck provides generated property tests, customizable generators, and failure shrinking for Swift projects. Its documented installation options and XCTest usage make its scope clear.
The facts
Each one read from SwiftCheck's own pages, with the date it was checked.
What it does
- Audience
- The project describes itself as QuickCheck for Swift and links a beginner-level tutorial playground for users new to its concepts.checked 9 Oct 2026
- Counterexamples
- When a generated test case fails, SwiftCheck shrinks the data toward a minimal counterexample.checked 8 Oct 2026
- Custom types
- Custom types can join generated testing by conforming to the `Arbitrary` protocol and providing generation and shrinking behavior.checked 9 Oct 2026
- Generated types
- The library implements `Arbitrary` for most Swift Standard Library types.checked 8 Oct 2026
- Generators
- The library provides generator combinators for choosing values, filtering generated values, and composing generators.checked 9 Oct 2026
- Installation
- The README describes installation through Swift Package Manager, Carthage, CocoaPods, or by adding the Xcode project as a framework dependency.checked 8 Oct 2026
- Integrations
- The README documents installation through Swift Package Manager, Carthage, CocoaPods, or by adding the Xcode project as a framework.checked 9 Oct 2026
- License
- SwiftCheck is released under the MIT license.checked 9 Oct 2026
- Property composition
- Properties can be combined with conjunction and labels, and can include preconditions that discard inputs when they do not hold.checked 9 Oct 2026
- Property testing
- Its `forAll` quantifier lets tests express properties that should hold across generated inputs.checked 9 Oct 2026
- Property tests
- Properties use the `forAll` quantifier and return values that conform to `Testable`.checked 8 Oct 2026
- Purpose
- SwiftCheck is a Swift testing library that automatically generates random data to test program properties.checked 9 Oct 2026
- Requirements
- The README lists OS X 10.9+ and iOS 7.0+ as supported system requirements.checked 8 Oct 2026
- Shrinking
- When a generated test case fails, SwiftCheck reduces the data toward a minimal counterexample.checked 9 Oct 2026
- Standard library types
- SwiftCheck implements `Arbitrary` for most Swift Standard Library types and `Testable` for `Bool` and related types.checked 9 Oct 2026
- Support and security
- The repository page links issue tracking and contribution guidance; the opened page does not state a support service or security certification.checked 9 Oct 2026
- Test framework
- The README demonstrates SwiftCheck properties inside an `XCTestCase` test class.checked 8 Oct 2026
Where it runs
- Platforms
- The README states support for OS X 10.9+ and iOS 7.0+.checked 9 Oct 2026
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