使用FsUnit.Xunit断言异常消息

Question

我试图使用FsUnit.Xunit断言某种异常类型和消息。有一些throwWithMessage函数随FsUnit而来。但是，当使用它代替throw函数时，fsc会发出以下错误：

C:\src\foo.fs(29,12): error FS0001: This expression was expected to have type '(unit -> unit) -> 'a' but here has type 'unit' 
C:\src\foo.fs(29,19): error FS0001: The type ''a -> NHamcrest.Core.CustomMatcher<obj>' is not compatible with the type 'NHamcrest.IMatcher<obj>' 
C:\src\foo.fs(29,12): error FS0001: This expression was expected to have type '(unit -> unit) -> 'a' but here has type 'unit'

这是一个不会编译的测试：

[<Fact>]
let ``Some test`` () =
    (fun () -> This.Throws("a", 10) |> ignore)
    |> should throwWithMessage "Some message" typeof<ArgumentException> //This is line 29
     //^ column index 12 is here
            //^ here is column index 19

我不知道这里出了什么问题。

版本：

• FsUnit/FsUnit.Xunit 3.1.0
• NHamcrest (由FsUnit.Xunit引用) 2.0.1
• Xunit 2.3.1

Answer 1

韦尔普，我漏掉了一些括号。这样做是可行的：

[<Fact>]
let ``Some test`` () =
    (fun () -> This.Throws("a", 10) |> ignore)
    |> should (throwWithMessage "Some message") typeof<ArgumentException>