使用Foq模拟Microsoft.Extensions.Logging.ILogger

Question

我很难用Foq来伪装微软的ILogger。

module MockExample

open Microsoft.Extensions.Logging
open NUnit.Framework
open Foq
//open Foq.Linq


// Implementation

type Worker (logger:ILogger) =

    member this.DoSomething (ok:bool) =
        if ok then
            logger.LogInformation("success 1")
        else
            logger.LogError("error 1")


// Test file

[<Test>]
let ``When error should log error`` () =
    
    // 1. let logger = Mock<ILogger>().SetupAction(fun lg -> lg.LogError("error")) ...Create() not availabe

    // 2.
    //let loggerMock = Mock<ILogger>(); 
    //loggerMock.SetupFunc(fun lg -> lg.LogError(It.IsAny<string>())) |> ignore  // .Returns() is not usable
    //let logger = loggerMock.Create()

    let logger = mock()

    // act
    Worker(logger).DoSomething(false)

    verify <@ logger.LogError("error 1") @> once
    //verify <@ logger.LogError("success 1") @> never

考试不及格。

我还尝试了其他语法，试图“模仿”LogError签名，但不使用cuccess。

编辑

我正试图嘲弄真正的记录器方法.Log(logLevel, message, ...)，但仍然无法让它正常工作：

​

​

实际上，我不知道该如何嘲笑这一点：

member Log<'TState> : logLevel: LogLevel * eventId: EventId * state: 'TState * ``exception`` : exn * formatter: System.Func<'TState,exn,string> -> unit

要提取/注册/比较state (它包含日志“消息”)。

编辑2

作为一种解决办法，我写了我对ILogger的嘲弄，它达到了目的，但我的问题仍然是“如何使用Foq来实现它”？

type LoggerMock () =
    let mutable informations:string list = []
    let mutable errors:string list = []

    member this.LoggedInformations = informations
    member this.LoggedErrors = errors    

    interface ILogger with
        member this.Log(logLevel: LogLevel, eventId: EventId, state: 'TState, ``exception``: exn, formatter: System.Func<'TState,exn,string>): unit = 
            match logLevel with
            | LogLevel.Information -> informations <- informations @ [state.ToString()]
            | LogLevel.Error -> errors <- errors @ [state.ToString()]
            | _ -> ()
        member this.BeginScope(state: 'TState): System.IDisposable = 
            raise (NotImplementedException())
        member this.IsEnabled(logLevel: LogLevel): bool = 
            raise (NotImplementedException())
                

[<Test>]
let ``When error should log error (custom mock)`` () =    
    let logger = LoggerMock()
    Worker(logger).DoSomething(false)
    logger.LoggedErrors |> should contain "error 2"

Answer 1

问题是，.LogError和.LogInformation实际上不是ILogger上的方法，而是包装ILogger实际定义的日志方法的扩展方法。

您需要模拟的方法是：ILogger.Log法

我相信扩展方法都称之为这一种方法。