Improve integration testing

[chingor13]

Ideally, we should be able to run tests against sample applications running test code in a webserver. This will allow us to test things like framework integrations, response codes, and other edge cases that are hard to test with only unit tests.

• Curl
• Doctrine
• Eloquent
• Grpc
• Guzzle
• Laravel
• Memcached
• Mysql
• PDO
• Postgres
• Symfony
• Wordpress

[jcchavezs]

I used this library for integration tests in zipkin: https://github.com/jcchavezs/httptest-php do you think it could work here?

[jcchavezs]

Any opinion on ^ @chingor13 @tmatsuo?

[chingor13]

Your library looks super useful for something like testing our Guzzle integrations.

As for testing framework integrations, we'd probably want some sample applications where we install the library and possibly run a local webserver and hit the app with requests - checking that stuff like trace context propagation works.

This issue is probably too general and we can break it into smaller issues.