How to complete the rspec put controller test from scaffold

Ok so this is how I do, I don’t pretend to strictly follow the best practices, but I focus on precision of my tests, clarity of my code, and fast execution of my suite.

So let take example of a UserController

1- I do not use FactoryGirl to define the attributes to post to my controller, because I want to keep control of those attributes. FactoryGirl is useful to create record, but you always should set manually the data involved in the operation you are testing, it’s better for readability and consistency.

In this regard we will manually define the posted attributes

let(:valid_update_attributes) { {first_name: 'updated_first_name', last_name: 'updated_last_name'} }

2- Then I define the attributes I expect for the updated record, it can be an exact copy of the posted attributes, but it can be that the controller do some extra work and we also want to test that. So let’s say for our example that once our user updated his personal information our controller automatically add a need_admin_validation flag

let(:expected_update_attributes) { valid_update_attributes.merge(need_admin_validation: true) }

That’s also where you can add assertion for attribute that must remain unchanged. Example with the field age, but it can be anything

let(:expected_update_attributes) { valid_update_attributes.merge(age: 25, need_admin_validation: true) }

3- I define the action, in a let block. Together with the previous 2 let I find it makes my specs very readable. And it also make easy to write shared_examples

let(:action) { patch :update, format: :js, id: record.id, user: valid_update_attributes }

4- (from that point everything is in shared example and custom rspec matchers in my projects) Time to create the original record, for that we can use FactoryGirl

let!(:record) { FactoryGirl.create :user, :with_our_custom_traits, age: 25 }

As you can see we manually set the value for age as we want to verify it did not change during the update action. Also, even if the factory already set the age to 25 I always overwrite it so my test won’t break if I change the factory.

Second thing to note: here we use let! with a bang. That is because sometimes you may want to test your controller’s fail action, and the best way to do that is to stub valid? and return false. Once you stub valid? you can’t create records for the same class anymore, therefor let! with a bang would create the record before the stub of valid?

5- The assertions itself (and finally the answer to your question)

before { action }
it {
  assert_record_values record.reload, expected_update_attributes
  is_expected.to redirect_to(record)
  expect(controller.notice).to eq('User was successfully updated.')
}

Summarize So adding all the above, this is how the spec looks like

describe 'PATCH update' do
  let(:valid_update_attributes) { {first_name: 'updated_first_name', last_name: 'updated_last_name'} }
  let(:expected_update_attributes) { valid_update_attributes.merge(age: 25, need_admin_validation: true) }
  let(:action) { patch :update, format: :js, id: record.id, user: valid_update_attributes }
  let(:record) { FactoryGirl.create :user, :with_our_custom_traits, age: 25 }
  before { action }
  it {
    assert_record_values record.reload, expected_update_attributes
    is_expected.to redirect_to(record)
    expect(controller.notice).to eq('User was successfully updated.')
  }
end

---

assert_record_values is the helper that will make your rspec simpler.

def assert_record_values(record, values)
  values.each do |field, value|
    record_value = record.send field
    record_value = record_value.to_s if (record_value.is_a? BigDecimal and value.is_a? String) or (record_value.is_a? Date and value.is_a? String)

    expect(record_value).to eq(value)
  end
end

As you can see with this simple helper when we expect for a BigDecimal, we can just write the following, and the helper do the rest

let(:expected_update_attributes) { {latitude: '0.8137713195'} }

---

So at the end, and to conclude, when you have written your shared_examples, helpers, and custom matchers, you can keep your specs super DRY. As soon as you start repeating the same thing in your controllers specs find how you can refactor this. It may take time at first, but when its done you can write the tests for a whole controller in few minutes

---

And a last word (I can’t stop, I love Rspec) here is how my full helper look like. It is usable for anything in fact, not just models.

def assert_records_values(records, values)
  expect(records.length).to eq(values.count), "Expected <#{values.count}> number of records, got <#{records.count}>\n\nRecords:\n#{records.to_a}"
  records.each_with_index do |record, index|
    assert_record_values record, values[index], index: index
  end
end

def assert_record_values(record, values, index: nil)
  values.each do |field, value|
    record_value = [field].flatten.inject(record) { |object, method| object.try :send, method }
    record_value = record_value.to_s if (record_value.is_a? BigDecimal and value.is_a? String) or (record_value.is_a? Date and value.is_a? String)

    expect_string_or_regexp record_value, value,
                            "#{"(index #{index}) " if index}<#{field}> value expected to be <#{value.inspect}>. Got <#{record_value.inspect}>"
  end
end

def expect_string_or_regexp(value, expected, message = nil)
  if expected.is_a? String
    expect(value).to eq(expected), message
  else
    expect(value).to match(expected), message
  end
end