Expand test suite for resolve data

[JeffRMoore]

Currently there is only one test case for "gets execution info in resolver" which does not test the breadth of execution info. It would be useful to expand the test cases around what information the resolve functions can expect to receive. Currently, only rootValue is tested from the GraphQLResolveInfo parameter. The suite should have the same kind of test for the other fields, especially fieldASTs, returnType, and parentType in nested and nonNull conditions. It should also test all three functions that receive GraphQLResolveInfo.

This can help make it easier to change the execute and resolve process without worrying about regressions.

https://github.com/graphql/graphql-js/blob/master/src/execution/__tests__/union-interface-test.js#L351

Extracting this from #304 as a separate issue.