Writing tests for RPC-based code?

[Jens Alfke]

Does anyone have advice on writing C++ automated tests for RPC-based code? (FWIW, I use the Catch2 unit-test framework, but I don’t restrict it to true ‘unit’ tests.) Say I’ve got an interface file, a class `Client` built atop classes generated from that interface, and a class `Server` that accepts TCP connections from a `Client`. I want to write a test that creates a Client and Server, connects them to each other, and then invokes some operations on the Client and asserts the correct results.

The first step of course is creating a connection. It looks like the simplest supported mechanism is to open a POSIX pipe and then create kj AsyncStreams on its two file descriptors. That means I’ll need an alternative Client constructor that takes a file descriptor or stream instead of a hostname/port…

I’d love to take a look at anyone’s test code that does stuff like this.

—Jens

[Kenton Varda]

Hi Jens,

Sorry for the slow reply.

Usually when I write tests, I don't actually use the RPC system, but rather have the client call the server directly running in the same thread. Remember that you can implicitly turn an `Own<MyInterface::Server>` into a `MyInterface::Client`, and then call it like a client:

    MyInterface::Client client = kj::heap<MyServerImpl>();

In theory, whether or not you have an actual RPC connection in between should be transparent.

-Kenton

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