tcapi: simplified interface

[makramkd]

Description

The tcapi.TestCase interface's methods were depending on ccv.Cfg and TestHarness, both of which make it difficult to run test cases on non-ephemeral environments like CLD environments.

This is the first step in making the test cases environment-agnostic:

• tcapi.TestCase methods now only take a context.Context, typically the test context.
• The construction of test cases will take a deployment.Environment and functional options that specify things like aggregator and indexer clients. This is because in CLD such clients are constructed from URLs that are retrieved from outside the datastore, compared to the URLs being in the ccv.Cfg in ephemeral envs.
• The basic test cases now make the aggregator and indexer guards optional; i.e. if aggregator and indexer clients are made available via the requisite functional options, the guards are enabled, else they are disabled. This kind of behaviour should probably be applied to all future TestCase implementations.

The next steps will be:

1. [P0] Migrate tcapi basic + token_transfer send path off SendMessage to BuildChainMessage + SendChainMessage. Aligns with the deprecation on Chain; same behavior, future-proof surface.
2. [P1] Refactor remaining e2e helpers that still center Lib + Cfg where tcapi-style env wiring is preferred, e.g. token verification / extra-args v2 tests: same explicit lane + NewCLDFOperationsEnvironment + optional clients pattern as smoke, where it reduces duplication without rewriting full v2 chaos/load.
3. [P1] Evaluate an optional TestEnvironment façade (DataStore + CLDFEnvironment). Single adapter + NewTestEnvironmentFromCfg would narrow what tcapi (and tests) depend on if CLDF churn is a concern.
4. [P2] Reconcile composable scenarios (MessageV3TestScenario, v2/v3 helpers) with tcapi.
5. [P2] After (4): revisit typing src / dst as ChainAsSource / ChainAsDestination (or a composed test-facing interface)

Testing

Checklist

• Breaking changes documented in changelog (see changelog directory)
• Cross link related PRs (in this or other repositories)
• just lint fix - no new lint errors
• just generate - mocks and protobufs are up to date

[github-actions]

Code coverage report:

Package	main	mk/simplify-tcapi	Diff
github.com/smartcontractkit/chainlink-ccv/aggregator	49.34%	49.35%	+0.01%
github.com/smartcontractkit/chainlink-ccv/bootstrap	47.23%	47.23%	+0.00%
github.com/smartcontractkit/chainlink-ccv/cli	65.13%	65.13%	+0.00%
github.com/smartcontractkit/chainlink-ccv/cmd	15.54%	15.54%	+0.00%
github.com/smartcontractkit/chainlink-ccv/common	56.54%	56.54%	+0.00%
github.com/smartcontractkit/chainlink-ccv/executor	45.97%	45.97%	+0.00%
github.com/smartcontractkit/chainlink-ccv/indexer	37.69%	37.68%	-0.01%
github.com/smartcontractkit/chainlink-ccv/integration	46.09%	46.09%	+0.00%
github.com/smartcontractkit/chainlink-ccv/pkg	84.62%	84.62%	+0.00%
github.com/smartcontractkit/chainlink-ccv/pricer	0.00%	0.00%	+0.00%
github.com/smartcontractkit/chainlink-ccv/protocol	63.75%	63.75%	+0.00%
github.com/smartcontractkit/chainlink-ccv/verifier	34.47%	34.47%	+0.00%
Total	46.20%	46.20%	+0.00%