0.3.0

• Added XCTUnimplemented, a function for constructing "unimplemented" closures that call XCTFail when invoked.

  Helpful for stubbing dependencies held in value types. For example, a common use of XCTest Dynamic Overlay:

  struct FactClient {
    var fetch: (Int) async throws -> String
  }
  
  extension FactClient {
    struct Unimplemented: Error {
      let endpoint: String
    }
  
    static let unimplemented = Self(
      fetch: { _ in
        XCTFail("Unimplemented: \(Self.self).fetch")
        throw Unimplemented(endpoint: "\(Self.self).fetch")
      }
    )
  }

  Can be simplified using XCTUnimplemented:

  extension FactClient {
    static let unimplemented = Self(
      fetch: XCTUnimplemented("\(Self.self).fetch")
    )
  }

• Changed: XCTFail now causes a runtime warning when called outside of tests.