Asserts that given result is a success, and if so, returns a success value

XCTAssertSuccess.swift

func XCTAssertSuccess<T, U>(
    _ result: @autoclosure () throws -> Result<T, U>,
    _ message: @autoclosure () -> String = "",
    file: StaticString = #filePath,
    line: UInt = #line
) -> T {
    do {
        let value = try result()

        switch value {
            case .success(let successValue):
                return successValue
            case .failure:
                XCTFail(message(), file: file, line: line)

                // Requires `continueAfterFailure` to be set to `false` on XCTestCase
                // Otherwise we will hit the fatal error and will not be able to continue
                // executing other tests
                fatalError("XCTAssertSuccess failed")
        }
    } catch {
        XCTFail(error.localizedDescription)

        // Requires `continueAfterFailure` to be set to `false` on XCTestCase
        // Otherwise we will hit the fatal error and will not be able to continue
        // executing other tests
        fatalError("XCTAssertSuccess failed")
    }
}