Ability to test the API to trigger specific error responses#61

The ability to call a GraphCMS endpoint and somehow specify a “test” mode, allowing us to select what kind of HTTP response we want to get, such as 502, 404?, 500, etc.

The goal is to simulate how our app would react in the event of a GraphCMS failure, in order to anticipate such failures.

Using a header, such as “gcms-force-response-code”: 500 for instance, could do the trick.

The ability to trigger specific error codes (at the HTTP and/or GraphQL levels) would be great. I can mock things out in unit tests, but legit E2E tests are important too.