Reducing duplication for JSON test input in RSpec - ruby

Question

I'm working on an application that reads JSON content from files and uses them to produce output. I'm testing with RSpec, and my specs are littered with JSON literal content all over the place. There's a ton of duplication, the files are big and hard to read, and it's getting to the point where it's so painful to add new cases, it's discouraging me from covering the corner cases.
Is there a good strategy for me to reuse large sections of JSON in my specs? I'd like to store the JSON somewhere that's not in the spec file, so I can focus on the test logic in the specs, and just understand which example JSON I'm using.
I understand that if the tests are hard to write, I may need to refactor the application, but until I can get the time to do that, I need to cover these test cases.
Below is one modified example from the application. I have to load many different JSON formatted strings like this, many are considerably larger and more complex:
RSpec.describe DataGenerator do
describe "#create_data" do
let(:input){
'{ "schema": "TEST_SCHEMA",
"tables": [
{ "name": "CASE_INFORMATION",
"rows": 1,
"columns": [
{ "name": "case_location_id", "type": "integer", "initial_value": "10000", "strategy": "next" },
{ "name": "id", "type": "integer", "delete_key": true, "initial_value": "10000", "strategy": "next" }
]
}
]
}'
}
it "generates the correct number of tables" do
generator = DataGenerator.new(input)
expect(generator.tables.size).to eq 1
end
end
end

Answer 1

We had a very same problem. We solved it by creating following helpers:
module JsonHelper
def get_json(name)
File.read(Rails.root.join 'spec', 'fixtures', 'json', "#{name}.json")
end
end
We moved all the json into files in spec/fixtures/json folder. Now you will eb able to use it as:
include JsonHelper
let(:input){ get_json :create_data_input }
Naturally you can tweak it as mach as you like/need. For example we were stubbing external services json responses, so we created get_service_response(service_name, request_name, response_type) helper. It is much more readable now when we use get_service_response('cdl', 'reg_lookup', 'invalid_reg')
assuming you put your json into 'create_data_input`