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@@ -32,6 +32,95 @@ spec/models/user_spec.rb|6 error| Failure/Error: u = described_class.new NoMeth
Except for the top-level `describe` block, always provide a String argument to
`describe`.
+## Don't assert against the absolute value of a sequence-generated attribute
+
+Consider the following factory:
+
+```ruby
+FactoryGirl.define do
+ factory :label do
+ sequence(:title) { |n| "label#{n}" }
+ end
+end
+```
+
+Consider the following API spec:
+
+```ruby
+require 'rails_helper'
+
+describe API::Labels do
+ it 'creates a first label' do
+ create(:label)
+
+ get api("/projects/#{project.id}/labels", user)
+
+ expect(response).to have_http_status(200)
+ expect(json_response.first['name']).to eq('label1')
+ end
+
+ it 'creates a second label' do
+ create(:label)
+
+ get api("/projects/#{project.id}/labels", user)
+
+ expect(response).to have_http_status(200)
+ expect(json_response.first['name']).to eq('label1')
+ end
+end
+```
+
+When run, this spec doesn't do what we might expect:
+
+```sh
+1) API::API reproduce sequence issue creates a second label
+ Failure/Error: expect(json_response.first['name']).to eq('label1')
+
+ expected: "label1"
+ got: "label2"
+
+ (compared using ==)
+```
+
+That's because FactoryGirl sequences are not reseted for each example.
+
+Please remember that sequence-generated values exist only to avoid having to
+explicitly set attributes that have a uniqueness constraint when using a factory.
+
+### Solution
+
+If you assert against a sequence-generated attribute's value, you should set it
+explicitly. Also, the value you set shouldn't match the sequence pattern.
+
+For instance, using our `:label` factory, writing `create(:label, title: 'foo')`
+is ok, but `create(:label, title: 'label1')` is not.
+
+Following is the fixed API spec:
+
+```ruby
+require 'rails_helper'
+
+describe API::Labels do
+ it 'creates a first label' do
+ create(:label, title: 'foo')
+
+ get api("/projects/#{project.id}/labels", user)
+
+ expect(response).to have_http_status(200)
+ expect(json_response.first['name']).to eq('foo')
+ end
+
+ it 'creates a second label' do
+ create(:label, title: 'bar')
+
+ get api("/projects/#{project.id}/labels", user)
+
+ expect(response).to have_http_status(200)
+ expect(json_response.first['name']).to eq('bar')
+ end
+end
+```
+
## Don't `rescue Exception`
See ["Why is it bad style to `rescue Exception => e` in Ruby?"][Exception].