Tests automation

[nolar]

The project is now in the proof-of-concept stage, and lacks the tests (beside the examples, manually executed during the development).

It needs some good unit tests to freeze its current state, so that we could continue to add new features safely.

Separate the tests into the internal tests and the external promises of the interface.

Add the coverage measurements.

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An estimation of topics to cover with the tests:

• Library's public interfaces (what is exported via the main module).
• Tests for object hierarchies #28 Object hierarchies and name/namespace/label parent-to-child propagation.
• Test registry and matching of handlers by causes #29 Registries and kopf.on decorators.
• Tests for last-seen state calculation and comparison #91 (+Test the event handling; and separate the cause detection from handling #82) Last-seen state manipulation.
• Test diffs calculation and manipulation #40 Diff calculation.
• Test the callback invocation protocol #34 Handler function invocation.
• Test watching and queueing of the events into workers/handlers #63 Event-loop running, task spawning.
• Test watching and queueing of the events into workers/handlers #63 Watching & queueing & per-object queues/workers.
• Test the event handling; and separate the cause detection from handling #82 Handling: cause detection and proper reaction.
• Test for finalizers #90 (+Test the event handling; and separate the cause detection from handling #82) Handling: finalizers adding/removing.
• Test the routines for the progress status storage #61 Handling: handler progress storage.
• Test the lifecycles #35 Handling: lifecycles and handler selection.
• Sub-handler invocation and context-vars setting.
• Peering and neighbourhood awareness.
• Test the CLI invocation, including logging in & preloading #39 CLI module loading/importing.
• Test the CLI invocation, including logging in & preloading #39 CLI commands and options, including cluster authentication.
• Consolidate all K8s API calls in one place #71 Mocked K8s client or API calls.
• Provide the basic testing tools for the operator developers #53 Test end-to-end with the real cluster (minikube) #54 Real-cluster execution and smoke tests.
• Measure the code coverage and upload reports #72 Coverage MOVED TO Measure test coverage #99

[nolar]

The remaining parts are implemented in nolar/kopf#519.