API testing

[Wondertan]

Currently, we test high-level APIs via Swamp through Go APIs. However:

• We don't test APIs of all the modules, like State
• We don't test APIs over RPC(only BlobModule is tested in atm)
  • So we see issues like "unmarshaling params for 'state.BalanceForAddress' (param: *types.Address): json: cannot unmarshal string into Go value of type types.Address" #2322

We should investigate which modules lack API coverage and ensure we test them directly over Go interfaces and over RPC.

[Wondertan]

Related #2240 as we need a way to nicely abstract nodes running over RPC and over direct Go

[Wondertan]

Per sync discussion with @distractedm1nd we agree on the following order of execution:

• Convert existing Swamp tests to run over RPC. Similar to a blob.
• Cover modules missing coverage
• Abstract Swamp to allow Knuu as the backend(swamp: Consider abstracting swamp and implementing swamp over knuu #2240)

[walldiss]

We should consider creating a testing app that imports the Celestia client and runs a test suite over the network. This will enable us to:

• Test RPC locally within the swamp against a real node connected to the same mocknet.
• Run tests against a mock node (akin to a unit test of the representation layer) to ensure the RPC client isn't broken.
• Run CI tests where the client and server are independent containers. These tests would be manual and only run during releases.