使用 FsUnit.Xunit 断言异常消息

Question

我正在尝试使用 FsUnit.Xunit 断言某种异常类型和消息。FsUnit附带了一些throwWithMessage功能。但是，当使用它代替throw函数 fsc 时，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'

这是无法编译的测试：

[<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

我不确定这里出了什么问题。

版本：

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

Answer 1

好吧，我错过了一些括号。这有效：

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