Read, close and replace the http Reponse Body

[Jakob3xD]

Description

With this change the http reponse body gets automatically closed by us so the user don't have to do it and it prevents unclosed connections if the user forgot to close it. This wont brake any existing implementations as you can still call .Close() on the Body.

Issues Resolved

https://pkg.go.dev/net/http#Client.Do

If the returned error is nil, the Response will contain a non-nil Body which the user is expected to close. If the Body is not both read to EOF and closed, the Client's underlying RoundTripper (typically Transport) may not be able to re-use a persistent TCP connection to the server for a subsequent "keep-alive" request.

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[dblock]

Looks good, needs a unit test, including to what happens with a double close by the caller.

[Jakob3xD]

Looks good, needs a unit test, including to what happens with a double close by the caller.

I am not 100% sure what kind of test you expect. Before this MR and after this MR the user can call Close() as often as they want. As the NopCloser just returns nil when calling Close it is obsolete to call it and to test it?

[dblock]

Looks good, needs a unit test, including to what happens with a double close by the caller.

I am not 100% sure what kind of test you expect. Before this MR and after this MR the user can call Close() as often as they want. As the NopCloser just returns nil when calling Close it is obsolete to call it and to test it?

I think of tests as expectations to prevent regressions. Imagine the implementation changes, what behavior do you expect?

• I expect that Close can be called multiple times on res.Body.
• I expect that NopCloser works as designed, i.e. returns nil when calling Close and that you can call Close multiple times, so those would be unit tests for NopCloser

[Jakob3xD]

@dblock I added a test. It will fail if the resp.Body is not a NopCloser. Without my added change it would fail with following error:

=== RUN   TestTransportBodyClose
    opensearchtransport_integration_test.go:145: Failed to read the reponse body: http: read on closed response body
--- FAIL: TestTransportBodyClose (0.00s)

[dblock]

Very good.