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f# - 如何在 FsUnit 的断言中忽略有区别的联合案例的值(value)?

转载 作者:行者123 更新时间:2023-12-04 22:57:42 25 4
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如何在 FsUnit 的断言中忽略有区别的联合案例的值(value)?

举个例子:

type TransactionAttempt = { 
Deposited:float
Requires:float
}

type RequestResult =
| Denied of TransactionAttempt
| Granted of Product

在我的测试中,我想这样做:
let display = balance |> select Pepsi
display |> should equal Denied

我不介意这样做:
display |> should equal (Denied _)

但是,我被迫这样做:
display |> should equal (Denied {Deposited=0.25; Requires=1.00})

请注意我必须对上面的表达式表达多么明确。

因此,我只想知道它是否被拒绝。我不在乎细节。

下面是实际测试:
[<Test>]
let ``Vending machine reflects more money required for selection``() =
// Setup
let balance = Quarter |> insert []

// Test
let display = balance |> select Pepsi

// Verify
display |> should equal (Denied {Deposited=0.25; Requires=1.00})

这是功能:
let select product balance =
let attempt = { Deposited=balance
Requires=product |> getPrice }

let paidInFull = attempt.Deposited >= attempt.Requires

if not paidInFull then
Denied attempt
else Granted product

这是整个域:
module Machine

type Deposit =
| Nickel
| Dime
| Quarter
| OneDollarBill
| FiveDollarBill

type TransactionAttempt = {
Deposited:float
Requires:float
}

type State =
| OutOfService
| PaymentReceived of Deposit
| WaitingForSelection
| NotPaidInFull of TransactionAttempt

type Product =
| Pepsi
| Coke
| Sprite
| MountainDew

type RequestResult =
| Denied of TransactionAttempt
| Granted of Product

(* Functions *)
open System

let display = function
| OutOfService -> "Out of Service"
| WaitingForSelection -> "Make selection"
| NotPaidInFull attempt -> sprintf "%s Required" ((attempt.Requires - attempt.Deposited).ToString("C2"))
| PaymentReceived deposit -> match deposit with
| Nickel -> "5¢"
| Dime -> "10¢"
| Quarter -> "25¢"
| OneDollarBill -> "$1.00"
| FiveDollarBill -> "$5.00"

let getBalance coins =
coins |> List.fold (fun acc d -> match d with
| Nickel -> acc + 0.05
| Dime -> acc + 0.10
| Quarter -> acc + 0.25
| OneDollarBill -> acc + 1.00
| FiveDollarBill -> acc + 5.00) 0.00
let insert balance coin =
coin::balance |> getBalance

let getPrice = function
| Pepsi -> 1.00
| Coke -> 1.00
| Sprite -> 1.00
| MountainDew -> 1.00

let select product balance =
let attempt = { Deposited=balance
Requires=product |> getPrice }

let paidInFull = attempt.Deposited >= attempt.Requires

if not paidInFull then
Denied attempt
else Granted product

最佳答案

我能想到的最简单的事情是为您想要的检查编写一个谓词:

let isDenied du =
match du with
| Denied _ -> true
| _ -> false

或者从 let f x = match x with ...相当于 let f = function ... ,可能是:
let isDenied = function Denied _ -> true | _ -> false

然后你的测试看起来像:
display |> isDenied |> should be True

请注意 True ,大写 T,是一个约束。如果您要与 bool 值进行比较,那么它将是
display |> isDenied |> should equal true

如果您发现必须编写大量这些自定义谓词,则可能有一个更通用的解决方案,涉及为 NUnit 或 XUnit 或您在后端使用的任何测试框架编写自定义约束。但作为 F# 的相对新手,您可能应该先使用简单的解决方案,然后再对其进行概括。

附言如果您决定编写自定义约束,请查看 https://github.com/fsprojects/FsUnit/blob/master/src/FsUnit.NUnit/FsUnit.fs (如果您使用 NUnit)或 https://github.com/fsprojects/FsUnit/blob/master/src/FsUnit.Xunit/FsUnit.fs (如果您使用的是 XUnit)以获得灵感。

关于f# - 如何在 FsUnit 的断言中忽略有区别的联合案例的值(value)?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38385602/

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