Start testing server responses against OpenAPI doc via Chai plugin

[rwalle61]

Signed-off-by: Richard Waller [email protected]

This uses the Chai OpenAPI response validator plugin (that @JonnySpruce and I made) to automatically test that PFE responds as our OpenAPI doc claims it does. This makes it easier to keep the two in sync, helping PFE's developers and users.

Notes:

• The new package has been legally cleared by Nik.
• When I connected our OpenAPI doc to this plugin, it immediately revealed 2 minor mistakes in our doc
  • (e.g. https://github.com/eclipse/codewind/pull/203/files#diff-2210d4bf0af7416f78b3cb8692501fc3L1563 misrepresented an array of ExtensionCommands as a single ExtensionCommand).
• This plugin can catch a lot of mistakes but not all of them:
  • If we specify that a response body can have certain properties, but forget to specify which are required, then this plugin assumes that we are following OpenAPI conventions to specify that the properties are optional
  • If we forget to specify what type (e.g. string, integer) a property should have, then this plugin assumes that we are following OpenAPI conventions to specify a multi-typed property (see Is type a required field for Schema Objects? OAI/OpenAPI-Specification#1657).
• we cannot use this to verify responses with no content (e.g. 204 No Content responses).
  • This is because in these cases chai-http automatically inserts a body of {}. So if our doc specifies that the response should contain No Content, this plugin will (accurately) flag the fact that {} is not null.
  • Luckily, we don't need to use this plugin in those scenarios anyway, since a simple res.should.have.status(X) will suffice.

[tetchel]

Love it