Conformance testing for channel data plane

[aslom]

Problem
We need conformance tests for channel data plane.

From channel specification
Extracted testable statements about HTTP transport:

• “Every Channel must expose either an HTTP or HTTPS endpoint.
• “The endpoint(s) MUST conform to HTTP Transport Binding for CloudEvents - Version 0.3.
• “It MUST support both Binary Content mode and Structured Content mode.
• “Channels MUST reject all HTTP event queueing requests with a method other than
  POST responding with HTTP status code 405 Method Not Supported
• “The Channel MUST respond with 202 Accepted if the event queueing request is accepted by the server.
• “If a Channel receives an event queueing request and is unable to parse a valid CloudEvent, then it MUST respond with 400 Bad Request.
• “Channels MUST output CloudEvents. The output MUST be via a binding specified in the CloudEvents specification.
• Every Channel MUST support sending events via Structured Content Mode HTTP Transport Binding.
• “Channels MUST NOT alter an event that goes through them. All CloudEvent attributes, including the data attribute, MUST be received at the subscriber identical to how they were received by the Channel. The only exception is the Distributed Tracing Extension Attribute, which is expected to change as the span id will be altered at every network hop.

Persona:
Which persona is this feature for?

Exit Criteria
A measurable (binary) test that would indicate that the problem has been resolved.

System Integrator, Contributors

Time Estimate (optional):
How many developer-days do you think this may take to resolve?
2-5d

Additional context (optional)

[aslom]

Proposed conformance test (TestChannelHttpTransport):

• Channel is created by test e2e (by default in-memory, can be configured ot be Kafka with helpers)
• Parametrize test
  • Create channel with http and https:// ?
  • Send CloudEvents V0.3 format binary and structured content
  • Send valid and invalid cloud-events (JSON and non-JSON data)
  • Send different HTTP methods - check only POST is accepted, GET but not HEAD? DELETE? All other HTTP methods?)
• Create channel and test sink that records received events - verify events are not modified (except for tracing headers) and that request and response HTTP status, headers, body are as expected - Check POST http:// or https:// and sending event in CloudEvents V0.3 format in binary and in structured content responds with 202. Send other versions and non-JSON payload and check response of 400 (any JSON vs non-JSON?)
• Report on MUST and SHOULD for different combinations of test parameters - report MUST failures as test failures

CC @Harwayne @lionelvillard @alanconway @matzew @lberk

[aslom]

I will start on first version of that test - should be relatively easy?
/assign @aslom

[Harwayne]

LGTM

[Harwayne]

A general observation, it may be easier to have multiple tests that each test one small thing, rather than a single test that tests everything. I leave it to your judgement on which you will actually choose to implement.

[akashrv]

/milestone v0.10.0

[Harwayne]

/project Channels In progress