1 files changed, 91 insertions, 4 deletions
diff --git a/doc/development/gotchas.md b/doc/development/gotchas.md
index 159d5ce286d..7bfc9cb361f 100644
--- a/doc/development/gotchas.md
+++ b/doc/development/gotchas.md
@@ -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].
@@ -41,9 +130,9 @@ Rubocop](https://gitlab.com/gitlab-org/gitlab-ce/blob/8-4-stable/.rubocop.yml#L9
 
 [Exception]: http://stackoverflow.com/q/10048173/223897
 
-## Don't use inline CoffeeScript/JavaScript in views
+## Don't use inline JavaScript in views
 
-Using the inline `:coffee` or `:coffeescript` Haml filters comes with a
+Using the inline `:javascript` Haml filters comes with a
 performance overhead. Using inline JavaScript is not a good way to structure your code and should be avoided.
 
 _**Note:** We've [removed these two filters](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/initializers/hamlit.rb)
@@ -51,9 +140,7 @@ in an initializer._
 
 ### Further reading
 
-- Pull Request: [Replace CoffeeScript block into JavaScript in Views](https://git.io/vztMu)
 - Stack Overflow: [Why you should not write inline JavaScript](http://programmers.stackexchange.com/questions/86589/why-should-i-avoid-inline-scripting)
-- Stack Overflow: [Performance implications of using :coffescript filter inside HAML templates?](http://stackoverflow.com/a/17571242/223897)
 
 ## ID-based CSS selectors need to be a bit more specific