I have a feeling that most people use async/await in new code, and none of the examples use it.

Also, from browsing random issues, better tests will be written using this structure. For example #543 is caused by not using async/await in tests.

// This passes!
it("should reset", async () => {
        request(app)
            .get("/reset")
            .expect(205);
});

This line confused me for quite a while: "You may set the body of a POST request as the second parameter of mock.post()". What this should say is: "you may set the mocked RESPONSE as the second parameter of mock.post()"

I suggest that the second parameter type should also accept a function as custom normalizer.

For example:

var request = require('superagent');
var serializer = require('superagent-serializer');

var customNormalizer = function(serializedRes) {
    // custom processing
    return serializedRes;
};

serializer(request, customNormalizer);