Mode d’emploi
- Copiez la commande et examinez le paquet avant de l’installer dans votre environnement agent.
- Consultez le document original pour les outils, identifiants et environnements requis.
- Décrivez les entrées et le livrable souhaité ; comparez la sortie aux sources.
npx skills add https://github.com/affaan-m/ecc --skill fsharp-testingAvant de commencer
- L’installation n’inclut ni abonnement au modèle, ni quota API, ni accès aux fichiers.
- Étoiles et installations reflètent l’activité, pas un test indépendant de qualité ou de sécurité.
Document Skill original
Rendu depuis le dépôt source en conservant titres, exemples, code, tableaux, liens et images.
F# Testing Patterns
Comprehensive testing patterns for F# applications using xUnit, FsUnit, Unquote, FsCheck, and modern .NET testing practices.
When to Activate
- Writing new tests for F# code
- Reviewing test quality and coverage
- Setting up test infrastructure for F# projects
- Debugging flaky or slow tests
Test Framework Stack
| Tool | Purpose |
|---|---|
| xUnit | Test framework (standard .NET ecosystem choice) |
| FsUnit.xUnit | F#-friendly assertion syntax for xUnit |
| Unquote | Assertion library using F# quotations for clear failure messages |
| FsCheck.xUnit | Property-based testing integrated with xUnit |
| NSubstitute | Mocking .NET dependencies |
| Testcontainers | Real infrastructure in integration tests |
| WebApplicationFactory | ASP.NET Core integration tests |
Unit Tests with xUnit + FsUnit
Basic Test Structure
fsharp
module OrderServiceTests
open Xunit
open FsUnit.Xunit
[<Fact>]
let ``create sets status to Pending`` () =
let order = Order.create "cust-1" [ validItem ]
order.Status |> should equal Pending
[<Fact>]
let ``confirm changes status to Confirmed`` () =
let order = Order.create "cust-1" [ validItem ]
let confirmed = Order.confirm order
confirmed.Status |> should be (ofCase <@ Confirmed @>)Assertions with Unquote
Unquote uses F# quotations so failure messages show the full expression that failed, not just "expected X got Y".
fsharp
module OrderValidationTests
open Xunit
open Swensen.Unquote
[<Fact>]
let ``PlaceOrder returns success when request is valid`` () =
let request = { CustomerId = "cust-123"; Items = [ validItem ] }
let result = OrderService.placeOrder request
test <@ Result.isOk result @>
[<Fact>]
let ``order total sums item prices`` () =
let items = [ { Sku = "A"; Quantity = 2; Price = 10m }
{ Sku = "B"; Quantity = 1; Price = 5m } ]
let total = Order.calculateTotal items
test <@ total = 25m @>
[<Fact>]
let ``validated email rejects empty input`` () =
let result = ValidatedEmail.create ""
test <@ Result.isError result @>Async Tests
fsharp
[<Fact>]
let ``PlaceOrder returns success when request is valid`` () = task {
let deps = createTestDeps ()
let request = { CustomerId = "cust-123"; Items = [ validItem ] }
let! result = OrderService.placeOrder deps request
test <@ Result.isOk result @>
}
[<Fact>]
let ``PlaceOrder returns error when items are empty`` () = task {
let deps = createTestDeps ()
let request = { CustomerId = "cust-123"; Items = [] }
let! result = OrderService.placeOrder deps request
test <@ Result.isError result @>
}Parameterized Tests with Theory
fsharp
[<Theory>]
[<InlineData("")>]
[<InlineData(" ")>]
let ``PlaceOrder rejects empty customer ID`` (customerId: string) =
let request = { CustomerId = customerId; Items = [ validItem ] }
let result = OrderService.placeOrder request
result |> should be (ofCase <@ Error @>)
[<Theory>]
[<InlineData("", false)>]
[<InlineData("a", false)>]
[<InlineData("user@example.com", true)>]
[<InlineData("user+tag@example.co.uk", true)>]
let ``IsValidEmail returns expected result`` (email: string, expected: bool) =
test <@ EmailValidator.isValid email = expected @>Property-Based Testing with FsCheck
Using FsCheck.xUnit
fsharp
open FsCheck
open FsCheck.Xunit
[<Property>]
let ``order total is always non-negative`` (items: NonEmptyList<PositiveInt * decimal>) =
let orderItems =
items.Get
|> List.map (fun (qty, price) ->
{ Sku = "SKU"; Quantity = qty.Get; Price = abs price })
let total = Order.calculateTotal orderItems
total >= 0m
[<Property>]
let ``serialization roundtrips`` (order: Order) =
let json = JsonSerializer.Serialize order
let deserialized = JsonSerializer.Deserialize<Order> json
deserialized = orderCustom Generators
fsharp
type OrderGenerators =
static member ValidEmail () =
gen {
let! user = Gen.elements [ "alice"; "bob"; "carol" ]
let! domain = Gen.elements [ "example.com"; "test.org" ]
return $"{user}@{domain}"
}
|> Arb.fromGen
[<Property(Arbitrary = [| typeof<OrderGenerators> |])>]
let ``valid emails pass validation`` (email: string) =
EmailValidator.isValid emailMocking Dependencies
Function Stubs (Preferred)
fsharp
let createTestDeps () =
let mutable savedOrders = []
{ FindOrder = fun id -> task { return Map.tryFind id testData }
SaveOrder = fun order -> task { savedOrders <- order :: savedOrders }
SendNotification = fun _ -> Task.CompletedTask }
[<Fact>]
let ``PlaceOrder saves the confirmed order`` () = task {
let mutable saved = []
let deps =
{ createTestDeps () with
SaveOrder = fun order -> task { saved <- order :: saved } }
let! _ = OrderService.placeOrder deps validRequest
test <@ saved.Length = 1 @>
}NSubstitute for .NET Interfaces
fsharp
open NSubstitute
[<Fact>]
let ``calls repository with correct ID`` () = task {
let repo = Substitute.For<IOrderRepository>()
repo.FindByIdAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>())
.Returns(Task.FromResult(Some testOrder))
let service = OrderService(repo)
let! _ = service.GetOrder(testOrder.Id, CancellationToken.None)
do! repo.Received(1).FindByIdAsync(testOrder.Id, Arg.Any<CancellationToken>())
}ASP.NET Core Integration Tests
fsharp
type OrderApiTests (factory: WebApplicationFactory<Program>) =
interface IClassFixture<WebApplicationFactory<Program>>
let client =
factory.WithWebHostBuilder(fun builder ->
builder.ConfigureServices(fun services ->
services.RemoveAll<DbContextOptions<AppDbContext>>() |> ignore
services.AddDbContext<AppDbContext>(fun options ->
options.UseInMemoryDatabase("TestDb") |> ignore) |> ignore))
.CreateClient()
[<Fact>]
member _.``GET order returns 404 when not found`` () = task {
let! response = client.GetAsync($"/api/orders/{Guid.NewGuid()}")
test <@ response.StatusCode = HttpStatusCode.NotFound @>
}Test Organization
tests/
MyApp.Tests/
Unit/
OrderServiceTests.fs
PaymentServiceTests.fs
Integration/
OrderApiTests.fs
OrderRepositoryTests.fs
Properties/
OrderPropertyTests.fs
Helpers/
TestData.fs
TestDeps.fsCommon Anti-Patterns
| Anti-Pattern | Fix |
|---|---|
| Testing implementation details | Test behavior and outcomes |
| Mutable shared test state | Fresh state per test |
Thread.Sleep in async tests | Use Task.Delay with timeout, or polling helpers |
Asserting on sprintf output | Assert on typed values and pattern matches |
Ignoring CancellationToken | Always pass and verify cancellation |
| Skipping property-based tests | Use FsCheck for any function with clear invariants |
Related Skills
dotnet-patterns- Idiomatic .NET patterns, dependency injection, and architecturecsharp-testing- C# testing patterns (shared infrastructure like WebApplicationFactory and Testcontainers applies to F# too)
Running Tests
bash
# Run all tests
dotnet test
# Run with coverage
dotnet test --collect:"XPlat Code Coverage"
# Run specific project
dotnet test tests/MyApp.Tests/
# Filter by test name
dotnet test --filter "FullyQualifiedName~OrderService"
# Watch mode during development
dotnet watch test --project tests/MyApp.Tests/
