Allow structured Nominatim lookup

[janko]

The following currently fails with an error:

Geocoder.search(nil, params: {
  street: "...",
  city: "...",
  country: "...",
  state: "...",
  postalcode: "...",
})

Structured query parameters(amenity, street, city, county, state, postalcode, country) cannot be used together with 'q' parameter.

We fix this by skipping including the q parameter in case structured query parameters are passed and query text would be blank.

Closes #1689

[alexreisner]

@janko thanks for this. I think your approach is good, just a few thoughts:

1. The purpose of your test is not clear to me. Perhaps it should be named something like test_q_is_empty_with_structured_lookup? It doesn't matter so much that you get a result back (since it's a fake result). Maybe the assertion should involve a Query object?
2. Are you sure the condition you've added (!query.params_given? || !query.sanitized_text.empty?) isn't inverted? It seems to me that q should be blank if there are no params given (but I might be confused).

[janko]

Thanks for the quick reply:

1. Since the test suite doesn't seem to be using mocking libraries such as WebMock, I'm not sure how to make assertions on which query parameters were (not) included in the Nominatim request. Do you maybe have some pointers?
2. I thought about the least awkward way to write this condition. I want to skip the q parameter if additional parameters were passed (e.g. street, city) AND no text query was passed, i.e. query.params_given? && query.sanitized_text.empty?. Since it's a conditional for when we should add the q parameter, we have to invert it, so it's if !(query.params_given? && query.sanitized_text.empty?), or if !query.params_given? || !query.sanitized_text.empty? if don't want parentheses.