I built a WCF Service that uses custom username and password authentication and I am testing it from the client app with the following code:
using (ServiceRe
The options mentioned in the comments above are good for testing. If you want something more robust that you can include in your code, then I think what you want to implement is a WCF Message Inspector.
More on how to do this on the client:
You can inspect or modify the incoming or outgoing messages across a WCF client by implementing a System.ServiceModel.Dispatcher.IClientMessageInspector and inserting it into the client runtime.
https://msdn.microsoft.com/en-us/library/ms733786(v=vs.110).aspx
And a good example:
https://weblogs.asp.net/paolopia/writing-a-wcf-message-inspector