Add Consumer.ConsumeTopic(topic, offset)

[wvanbergen]

Or another way to make the common case of consuming all partitions of a topic easier, without having to construct a Client object

[wvanbergen]

As an alternative, we can expose Topics() and Partitions(topic) from Client on the Consumer, so it's not necessary to instantiate a Client anymore for this common use case.

[eapache]

I'd prefer to just implement ConsumerTopic - that covers the common case, and it's really not that much work to call NewClient and then NewConsumerFromClient.

[wvanbergen]

It makes testing a lot harder, because you need to mock the entire Client.

Also for ConsumeTopic, you would have to specify a map of partition -> offset if you want to resume. It depends on your offset store if it is possible to figure out how many partitions you would need to include in a struct like that. (Kafka's FetchOffset does not, so you would have to call Partitions on the client anyway)

[eapache]

That just means we should really provide a mock client :P