Use integration test to cover key OTLP scenarios

[cijothomas]

Pre-req to #2142
We should improve the existing integration tests to add coverage for OTLP under various combinations of ExportProcessor/PeriodicReader and the networking library (reqwest/hyper/tonic).

The test infra already exists, but it is missing few things

1. Metric is untested - Done refactor integration tests and add metrics coverage #2432
2. Simple processor scenarios not covered.
3. tokio::main vs normal main
4. Any missing combinations.
5. reqwest-blocking support is not working, and commented out -

   opentelemetry-rust/scripts/integration_tests.sh

   Line 13 in f513768

   # cargo test --no-default-features --features "reqwest-blocking-client" -- --ignored

   . Need to be fixed.

[scottgerring]

Hey @cijothomas , I can take this one. Good opportunity to get into the code some more 🙌

[cijothomas]

Thanks! As mentioned offline, please start with adding Metrics (which is completely missing now), and then you can continue with the rest.

[lalitb]

Also, reqwest-blocking doesn't work as of now, and so is commented out from test. This could be for being called from within the async context. Added it to the description to make it complete. -

opentelemetry-rust/scripts/integration_tests.sh

Lines 12 to 13 in f513768

	# TODO - Uncomment the following lines once the reqwest-blocking-client feature is working.
	# cargo test --no-default-features --features "reqwest-blocking-client" -- --ignored

[cijothomas]

Also, reqwest-blocking doesn't work as of now, and so is commented out from test. This could be for being called from within the async context.

Yes, should be fixable with
#2400

[scottgerring]

Perfect! I'll get stuck in tail end of this week.

[cijothomas]

Re-opening as this is good to be kept as the parent issue tracking good coverage via integration tests.