fix #60

[hubo1016]

This PR adds async context manager support on Watch object, so the response is correctly closed when watch is stopped with stop() or by some exceptions.

fix #60

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@d57e9e9). Click here to learn what that means.
The diff coverage is 96.77%.

@@            Coverage Diff            @@
##             master      #61   +/-   ##
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  Coverage          ?   94.46%           
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  Files             ?       20           
  Lines             ?     1373           
  Branches          ?        0           
=========================================
  Hits              ?     1297           
  Misses            ?       76           
  Partials          ?        0

Impacted Files	Coverage Δ
kubernetes_asyncio/watch/watch.py	94.25% <100%> (ø)
kubernetes_asyncio/watch/watch_test.py	95.95% <93.75%> (ø)

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[tomplus]

I'm not sure if the context manager is necessary to fix the issue. What do you think about handling an exception in an iterator and close response object?

    async def __anext__(self):
        try:
            return await self.next()
        except:
            self.resp.close()
            self.resp = None
            raise

[hubo1016]

@tomplus The except clause solves the problem partially, but the response may still leak if an exception is raised in the async for structure. In this case, the __anext__ function is not called. In general, most async generator interfaces need a explicit close operation, either with aclose() or __aexit__. Usually async with is easier to use.

[tomplus]

Yes, it makes sense, thanks for working on this!

[tomplus]

Released in v8.1.0, thank you.