[BUG]: An item with the same key has already been added. Key: `Set-Cookie`

[ThaDaVos]

Description

When making API calls to the service of Viva Payments, I keep getting errors like below:

 fail    An error occurred in a plugin Exception Details: System.Exception: Exception thrown in user event
 ---> System.ArgumentException: An item with the same key has already been added. Key: Set-Cookie
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at DevProxy.Plugins.Inspection.DevToolsPlugin.AfterResponseAsync(Object sender, ProxyResponseArgs e)
   at DevProxy.Abstractions.FuncExtensions.InternalInvokeAsync[T](AsyncEventHandler`1 callback, Object sender, T args, ExceptionHandler exceptionFunc)
   --- End of inner exception stack trace ---

I guess due to this, my DevInspector Responses are also empty - so I can't really work with it now...
The requests are made using Microsoft Kiota

I saw the bug was also in the MockGeneratorPlugin: #358

Expected behaviour

No error? Or at least the Responses to be populated in the DevInspector

Actual behaviour

Error and empty responses in the DevInspector

Steps to reproduce

I guess it's Viva Payments specific - but probably all endpoints which violate the RFC 6265
https://www.rfc-editor.org/rfc/rfc6265#section-4.1.1

Dev Proxy Version

0.27.0

Operating system (environment)

Windows

Shell

PowerShell

Configuration file

{
    "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v0.27.0/rc.schema.json",
    "plugins": [
        {
            "name": "DevToolsPlugin",
            "enabled": true,
            "pluginPath": "~appFolder/plugins/dev-proxy-plugins.dll",
            "configSection": "devTools"
        }
    ],
    "devTools": {
        "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v0.27.0/devtoolsplugin.schema.json",
        "preferredBrowser": "Edge"
    },
    "urlsToWatch": [
        "https://demo-api.vivapayments.com/*",
        "https://api.vivapayments.com/*",
        "https://demo-accounts.vivapayments.com/connect/token",
        "https://accounts.vivapayments.com/connect/token"
    ],
    "logLevel": "debug",
    "newVersionNotification": "stable",
    "showSkipMessages": true,
    "showTimestamps": true
}

Additional Info

No response

[waldekmastykarz]

Thanks for letting us know of this and sorry for the trouble. We'll get this fixed asap.

[waldekmastykarz]

We need to see what's the best way to fix it because the Chrome DevTools Protocol lists headers as key-value pairs.

[ThaDaVos]

I would say, only pass the first on through to the DevTools - and give warnings in the Dev Proxy console about the dups - that way, at least the responses show up and if one is missing headers, they can see it inside the DevProxy console - best would be when showing the warning to show the Key and Value - this way it isn't fully lost

[waldekmastykarz]

Turns out the standard way to go about it to combine all headers into one and put all values in a comma-separated string. I've just opened a PR. We should be able to do a new beta release with the fix on Monday. Have a great weekend, and thanks again for bringing it up.

[ThaDaVos]

I don't see an update - will this be done in the next update? Or does one update the plugin separately?

[waldekmastykarz]

We've released a new beta just yesterday and had to wait for a few hours until it gets published on winget. It should be available now and you should see v0.28.0-beta.1 Otherwise, you can grab it from here: https://github.com/dotnet/dev-proxy/releases/tag/v0.28.0-beta.1. Thanks for checking