[Refactoring proposal] Test app structure refactoring

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• Problem/bug report.
• Feature request.
• Refactor proposal
• Request for support. Note: Please try to avoid submitting issues for support requests. Use Gitter instead.

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• I've searched for an existing issue.
• I've asked my question on Gitter and have not received a satisfactory answer.
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Description

Currently, we put all kind of components of our test app in side test/fixtures/active_record.rb. It contains schema, models, controllers and resources. The file’s name is quite misleading since it contains more than active_record related stuffs. And it’s a 2000 lines file, a little bit too long.

And in the meantime, test_helper.rb has the routes, test configurations, monkey-patches and test app configurations.

As a new contributor, I need to spend more time to figure out the test setup under this structure.

So I suggest we can do a small refactoring, to extract and put different types of components into their own files. Like:

test 
 |——— schema.rb # for schema
 |——— models.rb # for models
 |——— controllers.rb # for controllers
 |——— resources.rb # for resources
 |——— routes.rb # for routes
 |——— app.rb # for app configs
 |——— test_helper.rb # test configs, monkey-patchings and requires

Now we can just include these component files inside test_helper.rb and it’ll be more easier for new contributors to understand the test app.

Start by reading test/fixtures/active_record.rb and test_helper.rb to map the schema, models, controllers, resources, routes, configurations, and monkey-patches they contain. Extract each component type into the proposed test files and include them from test_helper.rb. Done means the test app retains its behavior while its structure matches the proposed layout.