无法使测试套件通过 golang “sayHello() used as value”

Question

我试图让这个测试套件通过命令提示符 (hello-world_test.go)：

package helloworld

import "testing"

func TestHelloWorld(t *testing.T) {

    output := sayHello()

    if "Hello, World!" != output {

        t.Fatalf("output: %s\nexpected: Hello,World!", output)

    }

}

我的代码如下（helloworld.go）：

package helloworld

import "fmt"

func sayHello() {

    fmt.Println("Hello, World!")

}

并且通过命令提示符的错误代码是：

C:\Users\Troy\exercism\go\hello-world\go test -v

# _/C_/Users/Troy/exercism/go/hello-world

.\hello-world_test.go:6: sayHello() used as value

FAIL    _/C_/Users/Troy/exercism/go/hello-world [build failed]