F＃测试结果是否为Some（any）

Question

我需要检查我的验证函数在失败或some时是否返回none。如果它返回Some<string>，则存在验证错误，否则它是有效的，函数返回None。 这是我的尝试，但它不是重构安全：

[<Property(Arbitrary=[| typeof<Strings.WithLenFrom1To100> |])>]
    let ``lengthValidator should return some error when the string's length is longer than expected``(str:string)=
        let maxValidLen = str.Length-1
        let actual = lengthValidator maxValidLen str

        let expected = Some(sprintf "Maximum string length is %i but %s contains %i characters" maxValidLen str str.Length)
        //How can I say **let expected = Some(anything) **instead

        test <@actual = expected@>

Answer 1

test <@ actual.IsSome @>