Question

我正在通过FParsec的教程，但调整代码以在xUnit下运行。运行此测试时：

open FParsec
open Xunit

exception ParseError of string
let parse parser input = 
    match run parser input with 
        | Success (result, _, _) -> result
        | Failure (error, _, _) -> raise (ParseError error) 

type UserState = unit
type Parser<'t> = Parser<'t, UserState>

let str s = pstring s
let floatBetweenBrackets:Parser<_> = str "[" >>. pfloat .>> str "]"

[<Fact>]
let ``Parsing [1.0] works`` () =
    let r = parse floatBetweenBrackets "[1.0]"
    Assert.Equal(1.0,r)

我失败了：

[23/10/17 13:31:53 Informational] ------ Run test started ------
[23/10/17 13:31:53 Informational] [xUnit.net 00:00:00.3299056] Received 1 results from 1 requests
[23/10/17 13:31:53 Informational] [xUnit.net 00:00:00.3306170]   Starting:    Experiments
[23/10/17 13:31:54 Error] [xUnit.net 00:00:00.5309115]     fSharpExperiments.FParsecTest.Parsing [1.0] works [FAIL]
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5325011]       System.NullReferenceException : Object reference not set to an instance of an object.
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5356227]       Stack Trace:
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5360697]            at FParsec.CharParsers.applyParser[Result,UserState](FSharpFunc`2 parser, CharStream`1 stream)
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5364446]            at FParsec.CharParsers.run@97.Invoke(CharStream`1 stream)
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5367866]            at FParsec.CharStream.ParseString[T,TUserState](String chars, Int32 index, Int32 length, FSharpFunc`2 parser, TUserState userState, String streamName)
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5371211]            at FParsec.CharParsers.run[Result](FSharpFunc`2 parser, String string)
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5374329]         C:\Users\jackc\Documents\Git\fsharpExperiments\Experiments\FParsec.fs(28,0): at fSharpExperiments.FParsecTest.parse[a](FSharpFunc`2 parser, String input)
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5377692]         C:\Users\jackc\Documents\Git\fsharpExperiments\Experiments\FParsec.fs(54,0): at fSharpExperiments.FParsecTest.Parsing [1.0] works()
[23/10/17 13:31:54 Informational] [xUnit.net 00:00:00.5479057]   Finished:    Experiments
[23/10/17 13:31:54 Informational] ========== Run test finished: 1 run (0:00:00.604968) ==========

这很奇怪，因为如果我在测试函数之外执行此操作它会运行正常。

let r = parse floatBetweenBrackets "[1.0]"
Assert.Equal(1.0,r)

r为float = 1.0且r = 1.0为真。

我错过了什么？

xUnit和FParsec“对象引用未设置为对象的实例”

0 个答案: