Swift Testing

Apple's modern testing framework for Swift: @Test functions, #expect and #require checks, parameterized tests and traits.

Definition

Introduced with Xcode 16, Swift Testing replaces XCTestCase subclasses and XCTAssert functions for unit tests. #expect records a failure and shows the values involved; #require stops the test. Tests run in parallel by default, suites are structs with a fresh instance per test, and @Test(arguments:) reports each input separately. UI tests and performance tests still use XCTest.

In practice

@Test(arguments: ["", "a", "abc"]) runs one validation test three times, with three separate results.

Related terms

Unit testA small, fast, automatic check that calls one piece of code with known input and compares the result with the expected value.
Test doubleA stand-in for a real dependency in a test, such as a fake payment gateway, so the test is fast, repeatable and safe.