swift-testing

SKILL.md

Swift Testing replaces XCTest with a modern macro-based approach that's more concise, has better async support, and runs tests in parallel by default. The core principle: if you learned XCTest, unlearn it—Swift Testing works differently.

| #expect(expression) | Soft check — continues on failure. Use for most assertions. | | #require(expression) | Hard check — stops test on failure. Use for preconditions only. |

| XCTAssert(expr) | #expect(expr) | | XCTAssertEqual(a, b) | #expect(a == b) | | XCTAssertNil(a) | #expect(a == nil) | | XCTAssertNotNil(a) | #expect(a != nil) | | try XCTUnwrap(a) | try #require(a) | | XCTAssertThrowsError | #expect(throws: ErrorType.self) { } | | XCTAssertNoThrow | #expect(throws: Never.self) { } |

Use when writing tests with Swift Testing (@Test, Source: johnrogers/claude-swift-engineering.

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