Python JSON serialization in test cases

[OR13]

Test cases contain JSON serializations that are python specific.

It would be better to ensure compact JSON is used (no extra spaces)... otherwise implementations will need to adjust their JSON serializer to match Python in order to to match the testcases.

Some additional string cases would also help force errors for any brittle reimplementation of python dumps.

{
  "I'm a 🧊, :cool: string": "with 🌶️, and :pepper:"
}

(, and : have spaces after them in the default JSON serialization used)

[danielfett]

Happy to accept PRs for new test cases :-)

I'll look into the JSON serializiation, although there are more parts that may vary, e.g., the order of elements. My expectation is that JSON is not compared as strings, but based on the decoded content.