withParams returns a confusing error message when the params do not match

[nolaneo]

We ran into a confusing failure message today when using withParams on a mock.

Our setup was something like this:

mock({
  url: '/users',
  type: 'GET',
}).withParams({
  rightParams: true
});

The test itself failed with a message like:

Pretender intercepted GET /users?rightParams=false but encountered an error: Nothing returned by handler for /users?rightParams=false. Remember to `return [status, headers, body];` in your route handler

Out problem was that it was not immediately obvious that we were calling the endpoint with incorrect params and that it was the withParams which was failing here; it took a while to figure out. (The params we expected were more complex / subtle than the example given! 😄 )

I think withParams should fail with a more explicit errors, maybe something like what assert.deepEqual gives?

expected '/users' to be called with:
{
  rightParams: true,
},
got:
{
  rightParams: false,
}

Here's a branch with an example of this failure: #389

cc @melintercom