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[Repo Assist] test: use TcpListener(0) for reliable free-port selection in HTTP test server #1724

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Merged
dsyme merged 2 commits into from
Apr 3, 2026
Merged

[Repo Assist] test: use TcpListener(0) for reliable free-port selection in HTTP test server #1724

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test: use TcpListener(0) for reliable free-port selection in HTTP tes…
github-actions[bot] Apr 3, 2026
87d8606
ci: trigger checks
github-actions[bot] Apr 3, 2026
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38 changes: 14 additions & 24 deletions tests/FSharp.Data.Core.Tests/Http.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ open System.Text
open System.Threading.Tasks
open Microsoft.AspNetCore.Builder
open Microsoft.AspNetCore.Http
open System.Net.NetworkInformation
open System.Net.Sockets

type ITestHttpServer =
inherit IDisposable
Expand Down Expand Up @@ -47,14 +47,14 @@ let startHttpLocalServer() =
} |> Async.StartAsTask :> Task
)) |> ignore

// Use TcpListener(0) to ask the OS for a free port, then release it.
// The TOCTOU window (between Stop and Kestrel's bind) is microseconds,
// far more reliable than the previous random-port-then-check approach.
let freePort =
let random = new System.Random()
let mutable port = random.Next(10000, 65000) // Use a random high port instead of a fixed port
while
IPGlobalProperties.GetIPGlobalProperties().GetActiveTcpListeners()
|> Array.map (fun x -> x.Port)
|> Array.contains port do
port <- random.Next(10000, 65000)
let listener = new TcpListener(System.Net.IPAddress.Loopback, 0)
listener.Start()
let port = (listener.LocalEndpoint :?> System.Net.IPEndPoint).Port
listener.Stop()
port

let baseAddress = $"http://127.0.0.1:{freePort}"
Expand All @@ -64,7 +64,7 @@ let startHttpLocalServer() =

{ new ITestHttpServer with
member this.Dispose() =
app.StopAsync() |> Async.AwaitTask |> ignore
app.StopAsync() |> Async.AwaitTask |> Async.RunSynchronously
printfn $"Stopped local http server with address {baseAddress}"
member this.WorkerTask = workerTask
member this.BaseAddress = baseAddress }
Expand Down Expand Up @@ -294,22 +294,12 @@ let testFormDataBodySize (size: int) =

[<Test; TestCaseSource("testFormDataSizesInBytes")>]
let testMultipartFormDataBodySize (size: int) =
// Skip this test on Windows when running in CI because of flaky port binding behavior on some Windows CI agents.
let isWindows = System.Runtime.InteropServices.RuntimeInformation.IsOSPlatform(System.Runtime.InteropServices.OSPlatform.Windows)
let inCi =
let env v = Environment.GetEnvironmentVariable v
[ "CI"; "GITHUB_ACTIONS"; "TF_BUILD"; "APPVEYOR"; "GITLAB_CI"; "JENKINS_URL" ]
|> List.exists (fun e -> not (String.IsNullOrEmpty (env e)))

if isWindows && inCi then
Assert.Ignore("Skipping test on Windows in CI")
else
use localServer = startHttpLocalServer()
let bodyString = seq {for _i in 0..size -> "x\n"} |> String.concat ""
let multipartItem = [ MultipartItem("input", "input.txt", new MemoryStream(Encoding.UTF8.GetBytes(bodyString)) :> Stream) ]
let body = Multipart(Guid.NewGuid().ToString(), multipartItem)
use localServer = startHttpLocalServer()
let bodyString = seq {for _i in 0..size -> "x\n"} |> String.concat ""
let multipartItem = [ MultipartItem("input", "input.txt", new MemoryStream(Encoding.UTF8.GetBytes(bodyString)) :> Stream) ]
let body = Multipart(Guid.NewGuid().ToString(), multipartItem)

Assert.DoesNotThrowAsync(fun () -> Http.AsyncRequest (url= localServer.BaseAddress + "/200", httpMethod="POST", body=body, timeout = 10000) |> Async.Ignore |> Async.StartAsTask :> _)
Assert.DoesNotThrowAsync(fun () -> Http.AsyncRequest (url= localServer.BaseAddress + "/200", httpMethod="POST", body=body, timeout = 10000) |> Async.Ignore |> Async.StartAsTask :> _)

[<Test>]
let ``escaping of url parameters`` () =
Expand Down
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