Function with a Trailing closure:

code(for: "Hello world") {

func hello(_ name: String? = nil) -> String {
      return "Hello, \(name ?? "World")!"
}
}

Unit tests for HelloWorld:

public class HelloWorldUnitTests: XCTestCase {

func testHello() {

      XCTAssertEqual(hello(), "Hello, World!")
  }
  static var allTests: [(String, (HelloWorldUnitTests) -> () throws -> Void)] {
      return [
          ("testHello", testHello),
      ]

If I make hello() as public without closure, tests were passed.I want to make it work with trailing closure within code function. Please help me with this