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Compatibility, Deprecation, and Migration Plan

• What impact (if any) will there be on existing users?
• If we are changing behavior how will we phase out the older behavior?
• If we need special migration tools, describe them here.
• When will we remove the existing behavior?

Rejected Alternatives

Until we are refactoring with these new MockStateStores, there shouldn't be any compatibility issues. But the next phase should be refactoring, including:

1) Remove and refactor redundant MockStores (i.e. org.apache.kafka.test.MockKeyValueStore)

2) Examine the current tests (i.e. org.apache.kafka.streams.TopologyTest) and refactor with the new MockStateStores.

Rejected Alternatives

1) Rebuilding a MockStateStores vs extending an InMemoryStore

• If we are rebuilding the functionality of a store from scratch in memory, it will basically act like an InMemoryStore.

2) If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.