Add more fuzz tests

[dstepanov]

No description provided.

[yawkat]

I don't think the client tests will work unfortunately because the server is fully embedded

[yawkat]

@dstepanov you can test the fuzz target locally like this:

    public static void main(String[] args) {
        LocalJazzerRunner.create(EmbeddedHttpTarget.class).reproduce("""
            POST /redirect/echo-publisher HTTP/1.1
            Content-Length: 3

            foo
            """.stripIndent().getBytes(StandardCharsets.UTF_8));
    }

[dstepanov]

it's not exposed on a port?

[yawkat]

No, it's fully embedded, no tcp. It's for performance and reproducibility.

Maybe it's possible to build a tcp-based target too, but I've not explored it yet

[dstepanov]

Can we start one extra server for this use case? Or this tests don't make sense? It would be nice to test the client as well

[yawkat]

In principle it's possible. There's a few options:

• Create a new target 'NioHttpTarget' which starts an actual tcp server for the test. Probably worthwhile anyway because an embedded env does not match a tcp env perfectly. But it needs some work to make it fast & reliable
• Create a new target that specifically tests the client against a "mock" TCP server fed by fuzzer input. This could either be tcp or embedded. Would also need some thought on which client errors are "allowed" and should not trip the fuzzer.
• In the existing EmbeddedHttpTarget, hook up the client to the existing server using an embedded channel. In core ConnectionManagerSpec kind of does this already, so it's possible.

Definitely possible but unfortunately also needs target changes.