Merge branch 'master' into 8-4-stable

CHANGELOG

@@ -42,6 +42,7 @@ v 8.4.0 (unreleased)
   - Ajax filter by message for commits page
   - API: Add support for deleting a tag via the API (Robert Schilling)
   - Allow subsequent validations in CI Linter
+  - Fix Encoding::CompatibilityError bug when markdown content has some complex URL (Jason Lee)
 
 v 8.3.4
   - Use gitlab-workhorse 0.5.4 (fixes API routing bug)
@@ -59,6 +60,8 @@ v 8.3.3
   - Fix Error 500 when visiting build page of project with nil runners_token (Stan Hu)
   - Use WOFF versions of SourceSansPro fonts
   - Fix regression when builds were not generated for tags created through web/api interface
+  - Fix: maintain milestone filter between Open and Closed tabs (Greg Smethells)
+  - Fix missing artifacts and build traces for build created before 8.3
 
 v 8.3.2
   - Disable --follow in `git log` to avoid loading duplicate commit data in infinite scroll (Stan Hu)

CONTRIBUTING.md

@@ -334,9 +334,9 @@ merge request:
 1.  [CoffeeScript](https://github.com/thoughtbot/guides/tree/master/style/coffeescript)
 1.  [Shell commands](doc/development/shell_commands.md) created by GitLab
     contributors to enhance security
-1.  [Markdown](http://www.cirosantilli.com/markdown-styleguide)
 1.  [Database Migrations](doc/development/migration_style_guide.md)
-1.  [Documentation styleguide](doc_styleguide.md)
+1.  [Markdown](http://www.cirosantilli.com/markdown-styleguide)
+1.  [Documentation styleguide](doc/development/doc_styleguide.md)
 1.  Interface text should be written subjectively instead of objectively. It
     should be the GitLab core team addressing a person. It should be written in
     present time and never use past tense (has been/was). For example instead

app/controllers/admin/application_settings_controller.rb

@@ -73,6 +73,7 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
       :metrics_pool_size,
       :metrics_timeout,
       :metrics_method_call_threshold,
+      :metrics_sample_interval,
       :recaptcha_enabled,
       :recaptcha_site_key,
       :recaptcha_private_key,

app/helpers/application_helper.rb

@@ -266,7 +266,7 @@ module ApplicationHelper
       state: params[:state],
       scope: params[:scope],
       label_name: params[:label_name],
-      milestone_id: params[:milestone_id],
+      milestone_title: params[:milestone_title],
       assignee_id: params[:assignee_id],
       author_id: params[:author_id],
       sort: params[:sort],

app/models/hooks/web_hook.rb

@@ -48,8 +48,8 @@ class WebHook < ActiveRecord::Base
     else
       post_url = url.gsub("#{parsed_url.userinfo}@", "")
       auth = {
-        username: URI.decode(parsed_url.user),
-        password: URI.decode(parsed_url.password),
+        username: CGI.unescape(parsed_url.user),
+        password: CGI.unescape(parsed_url.password),
       }
       response = WebHook.post(post_url,
                               body: data.to_json,

app/models/project_services/hipchat_service.rb

@@ -120,13 +120,13 @@ class HipchatService < Service
     message << "#{push[:user_name]} "
     if Gitlab::Git.blank_ref?(before)
       message << "pushed new #{ref_type} <a href=\""\
-                 "#{project_url}/commits/#{URI.escape(ref)}\">#{ref}</a>"\
+                 "#{project_url}/commits/#{CGI.escape(ref)}\">#{ref}</a>"\
                  " to #{project_link}\n"
     elsif Gitlab::Git.blank_ref?(after)
       message << "removed #{ref_type} <b>#{ref}</b> from <a href=\"#{project.web_url}\">#{project_name}</a> \n"
     else
       message << "pushed to #{ref_type} <a href=\""\
-                  "#{project.web_url}/commits/#{URI.escape(ref)}\">#{ref}</a> "
+                  "#{project.web_url}/commits/#{CGI.escape(ref)}\">#{ref}</a> "
       message << "of <a href=\"#{project.web_url}\">#{project.name_with_namespace.gsub!(/\s/,'')}</a> "
       message << "(<a href=\"#{project.web_url}/compare/#{before}...#{after}\">Compare changes</a>)"
 
@@ -255,8 +255,8 @@ class HipchatService < Service
     status = data[:commit][:status]
     duration = data[:commit][:duration]
 
-    branch_link = "<a href=\"#{project_url}/commits/#{URI.escape(ref)}\">#{ref}</a>"
-    commit_link = "<a href=\"#{project_url}/commit/#{URI.escape(sha)}/builds\">#{Commit.truncate_sha(sha)}</a>"
+    branch_link = "<a href=\"#{project_url}/commits/#{CGI.escape(ref)}\">#{ref}</a>"
+    commit_link = "<a href=\"#{project_url}/commit/#{CGI.escape(sha)}/builds\">#{Commit.truncate_sha(sha)}</a>"
 
     "#{project_link}: Commit #{commit_link} of #{branch_link} #{ref_type} by #{user_name} #{humanized_status(status)} in #{duration} second(s)"
   end

app/views/admin/application_settings/_form.html.haml

@@ -202,6 +202,13 @@
         .help-block
           A method call is only tracked when it takes longer to complete than
           the given amount of milliseconds.
+    .form-group
+      = f.label :metrics_sample_interval, 'Sampler Interval (sec)', class: 'control-label col-sm-2'
+      .col-sm-10
+        = f.number_field :metrics_sample_interval, class: 'form-control'
+        .help-block
+          The sampling interval in seconds. Sampled data includes memory usage,
+          retained Ruby objects, file descriptors and so on.
 
   %fieldset
     %legend Spam and Anti-bot Protection

app/views/groups/group_members/_new_group_member.html.haml

@@ -4,7 +4,7 @@
     .col-sm-10
       = users_select_tag(:user_ids, multiple: true, class: 'input-large', scope: :all, email_user: true)
       .help-block
-        Search for existing users or invite new ones using their email address.
+        Search for users by name, username, or email, or invite new ones using their email address.
 
   .form-group
     = f.label :access_level, "Group Access", class: 'control-label'

app/views/projects/project_members/_new_project_member.html.haml

@@ -4,7 +4,7 @@
     .col-sm-10
       = users_select_tag(:user_ids, multiple: true, class: 'input-large', scope: :all, email_user: true)
       .help-block
-        Search for existing users or invite new ones using their email address.
+        Search for users by name, username, or email, or invite new ones using their email address.
 
   .form-group
     = f.label :access_level, "Project Access", class: 'control-label'

config/initializers/1_settings.rb

@@ -11,7 +11,7 @@ class Settings < Settingslogic
 
     # get host without www, thanks to http://stackoverflow.com/a/6674363/1233435
     def get_host_without_www(url)
-      url = URI.encode(url)
+      url = CGI.escape(url)
       uri = URI.parse(url)
       uri = URI.parse("http://#{url}") if uri.scheme.nil?
       host = uri.host.downcase

db/migrate/20160113111034_add_metrics_sample_interval.rb

+class AddMetricsSampleInterval < ActiveRecord::Migration
+  def change
+    add_column :application_settings, :metrics_sample_interval, :integer,
+      default: 15
+  end
+end

doc/README.md

@@ -70,6 +70,8 @@
 
 ## Contributor documentation
 
+- [Documentation styleguide](development/doc_styleguide.md) Use this styleguide if you are
+  contributing to documentation.
 - [Development](development/README.md) Explains the architecture and the guidelines for shell commands.
 - [Legal](legal/README.md) Contributor license agreements.
 - [Release](release/README.md) How to make the monthly and security releases.

doc/api/projects.md

@@ -76,7 +76,10 @@ Parameters:
       "updated_at": "2013-09-30T13: 46: 02Z"
     },
     "archived": false,
-    "avatar_url": "http://example.com/uploads/project/avatar/4/uploads/avatar.png"
+    "avatar_url": "http://example.com/uploads/project/avatar/4/uploads/avatar.png",
+    "shared_runners_enabled": true,
+    "forks_count": 0,
+    "star_count": 0
   },
   {
     "id": 6,
@@ -129,7 +132,11 @@ Parameters:
       }
     },
     "archived": false,
-    "avatar_url": null
+    "avatar_url": null,
+    "shared_runners_enabled": true,
+    "forks_count": 0,
+    "star_count": 0,
+    "runners_token": "b8547b1dc37721d05889db52fa2f02"
   }
 ]
 ```
@@ -244,7 +251,11 @@ Parameters:
     }
   },
   "archived": false,
-  "avatar_url": "http://example.com/uploads/project/avatar/3/uploads/avatar.png"
+  "avatar_url": "http://example.com/uploads/project/avatar/3/uploads/avatar.png",
+  "shared_runners_enabled": true,
+  "forks_count": 0,
+  "star_count": 0,
+  "runners_token": "b8bc4a7a29eb76ea83cf79e4908c2b"
 }
 ```
 

doc/development/doc_styleguide.md

+# Documentation styleguide
+
+This styleguide recommends best practices to improve documentation and to keep
+it organized and easy to find.
+
+## Naming
+
+- When creating a new document and it has more than one word in its name,
+  make sure to use underscores instead of spaces or dashes (`-`). For example,
+  a proper naming would be `import_projects_from_github.md`. The same rule
+  applies to images.
+
+## Text
+
+- Split up long lines, this makes it much easier to review and edit. Only
+  double line breaks are shown as a full line break in [GitLab markdown][gfm].
+  80-100 characters is a good line length
+- Make sure that the documentation is added in the correct directory and that
+  there's a link to it somewhere useful
+- Do not duplicate information
+- Be brief and clear
+- Unless there's a logical reason not to, add documents in alphabetical order
+- Write in US English
+- Use [single spaces][] instead of double spaces
+
+## Formatting
+
+- Use dashes (`-`) for unordered lists instead of asterisks (`*`)
+- Use the number one (`1`) for ordered lists
+- Use underscores (`_`) to mark a word or text in italics
+- Use double asterisks (`**`) to mark a word or text in bold
+- When using lists, prefer not to end each item with a period. You can use
+  them if there are multiple sentences, just keep the last sentence without
+  a period
+
+## Headings
+
+- Add only one H1 title in each document, by adding `#` at the beginning of
+  it (when using markdown). For subheadings, use `##`, `###` and so on
+- Avoid putting numbers in headings. Numbers shift, hence documentation anchor
+  links shift too, which eventually leads to dead links. If you think it is
+  compelling to add numbers in headings, make sure to at least discuss it with
+  someone in the Merge Request
+- When introducing a new document, be careful for the headings to be
+  grammatically and syntactically correct. It is advised to mention one or all
+  of the following GitLab members for a review: `@axil`, `@rspeicher`,
+  `@dblessing`, `@ashleys`, `@nearlythere`. This is to ensure that no document
+  with wrong heading is going live without an audit, thus preventing dead links
+  and redirection issues when corrected
+- Leave exactly one newline after a heading
+
+## Links
+
+- If a link makes the paragraph to span across multiple lines, do not use
+  the regular Markdown approach: `[Text](https://example.com)`. Instead use
+  `[Text][identifier]` and at the very bottom of the document add:
+  `[identifier]: https://example.com`. This is another way to create Markdown
+  links which keeps the document clear and concise. Bonus points if you also
+  add an alternative text: `[identifier]: https://example.com "Alternative text"`
+  that appears when hovering your mouse on a link
+
+## Images
+
+- Place images in a separate directory named `img/` in the same directory where
+  the `.md` document that you're working on is located. Always prepend their
+  names with the name of the document that they will be included in. For
+  example, if there is a document called `twitter.md`, then a valid image name
+  could be `twitter_login_screen.png`.
+- Images should have a specific, non-generic name that will differentiate them.
+- Keep all file names in lower case.
+- Consider using PNG images instead of JPEG.
+
+Inside the document:
+
+- The Markdown way of using an image inside a document is:
+  `![Proper description what the image is about](img/document_image_title.png)`
+- Always use a proper description for what the image is about. That way, when a
+  browser fails to show the image, this text will be used as an alternative
+  description
+- If there are consecutive images with little text between them, always add
+  three dashes (`---`) between the image and the text to create a horizontal
+  line for better clarity
+- If a heading is placed right after an image, always add three dashes (`---`)
+  between the image and the heading
+
+## Notes
+
+- Notes should be in italics with the word `Note:` being bold. Use this form:
+  `_**Note:** This is something to note._`. If the note spans across multiple
+  lines it's OK to split the line.
+
+## New features
+
+- Every piece of documentation that comes with a new feature should declare the
+  GitLab version that feature got introduced. Right below the heading add a
+  note: `_**Note:** This feature was introduced in GitLab 8.3_`
+- If possible every feature should have a link to the MR that introduced it.
+  The above note would be then transformed to:
+  `_**Note:** This feature was [introduced][ce-1242] in GitLab 8.3_`, where
+  the [link identifier](#links) is named after the repository (CE) and the MR
+  number
+- If the feature is only in GitLab EE, don't forget to mention it, like:
+  `_**Note:** This feature was introduced in GitLab EE 8.3_`. Otherwise, leave
+  this mention out
+
+## API
+
+Here is a list of must-have items. Use them in the exact order that appears
+on this document. Further explanation is given below.
+
+- Every method must have the REST API request. For example:
+
+    ```
+    GET /projects/:id/repository/branches
+    ```
+
+- Every method must have a detailed
+  [description of the parameters](#method-description).
+- Every method must have a cURL example.
+- Every method must have a response body (in JSON format).
+
+### Method description
+
+Use the following table headers to describe the methods. Attributes should
+always be in code blocks using backticks (`).
+
+```
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+```
+
+Rendered example:
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `user`  | string | yes | The GitLab username |
+
+### cURL commands
+
+- Use `https://gitlab.example.com/api/v3/` as an endpoint.
+- Wherever needed use this private token: `9koXpg98eAheJpvBs5tK`.
+- Always put the request first. `GET` is the default so you don't have to
+  include it.
+- Use double quotes to the URL when it includes additional parameters.
+- Prefer to use examples using the private token and don't pass data of
+  username and password.
+
+| Methods | Description |
+| ------- | ----------- |
+| `-H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK"` | Use this method as is, whenever authentication needed |
+| `-X POST`   | Use this method when creating new objects |
+| `-X PUT`    | Use this method when updating existing objects |
+| `-X DELETE` | Use this method when removing existing objects |
+
+### cURL Examples
+
+Below is a set of [cURL][] examples that you can use in the API documentation.
+
+#### Simple cURL command
+
+Get the details of a group:
+
+```bash
+curl -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v3/groups/gitlab-org
+```
+
+#### cURL example with parameters passed in the URL
+
+Create a new project under the authenticated user's namespace:
+
+```bash
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects?name=foo"
+```
+
+#### Post data using cURL's --data
+
+Instead of using `-X POST` and appending the parameters to the URI, you can use
+cURL's `--data` option. The example below will create a new project `foo` under
+the authenticated user's namespace.
+
+```bash
+curl --data "name=foo" -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects"
+```
+
+#### Post data using JSON content
+
+_**Note:** In this example we create a new group. Watch carefully the single
+and double quotes._
+
+```bash
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" -H "Content-Type: application/json" --data '{"path": "my-group", "name": "My group"}' https://gitlab.example.com/api/v3/groups
+```
+
+#### Post data using form-data
+
+Instead of using JSON or urlencode you can use multipart/form-data which
+properly handles data encoding:
+
+```bash
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" -F "title=ssh-key" -F "key=ssh-rsa AAAAB3NzaC1yc2EA..." https://gitlab.example.com/api/v3/users/25/keys
+```
+
+The above example is run by and administrator and will add an SSH public key
+titled ssh-key to user's account which has an id of 25.
+
+#### Escape special characters
+
+Spaces or slashes (`/`) may sometimes result to errors, thus it is recommended
+to escape them when possible. In the example below we create a new issue which
+contains spaces in its title. Observe how spaces are escaped using the `%20`
+ASCII code.
+
+```bash
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/42/issues?title=Hello%20Dude"
+```
+
+Use `%2F` for slashes (`/`).
+
+#### Pass arrays to API calls
+
+The GitLab API sometimes accepts arrays of strings or integers. For example, to
+restrict the sign-up e-mail domains of a GitLab instance to `*.example.com` and
+`example.net`, you would do something like this:
+
+```bash
+curl -X PUT -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" -d "restricted_signup_domains[]=*.example.com" -d "restricted_signup_domains[]=example.net" https://gitlab.example.com/api/v3/application/settings
+```
+
+[cURL]: http://curl.haxx.se/ "cURL website"
+[single spaces]: http://www.slate.com/articles/technology/technology/2011/01/space_invaders.html
+[gfm]: http://doc.gitlab.com/ce/markdown/markdown.html#newlines "GitLab flavored markdown documentation"

doc_styleguide.md

 # Documentation styleguide
 
-This styleguide recommends best practices to improve documentation and to keep it organized and easy to find. 
-
-## Text
-
-- Split up long lines, this makes it much easier to review and edit. Only
-double line breaks are shown as a full line break in markdown. 80 characters
-is a good line length.
-- For subtitles, make sure to start with the largest and go down, meaning:
-`#` for the title, `##` for subtitles and `###` for subtitles of the subtitles, etc.
-- Make sure that the documentation is added in the correct directory and that there's a link to it somewhere useful.
-- Add only one H1 or title in each document, by adding '#' at the begining of it (when using markdown). 
-For subtitles, use '##', '###' and so on.
-- Do not duplicate information.
-- Be brief and clear.
-- Whenever it applies, add documents in alphabetical order.
-- Write in US English
-- Use [single spaces](http://www.slate.com/articles/technology/technology/2011/01/space_invaders.html) instead of double spaces.
-
-## Images
-
-- Create a directory to store the images with the specific name of the document where the images belong. 
-It could be in the same directory where the .md document that you're working on is located.
-- Images should have a specific, non-generic name that will differentiate them.
-- Keep all file names in lower case.
\ No newline at end of file
+Moved to [development/doc_styleguide](doc/development/doc_styleguide.md).

lib/api/entities.rb

@@ -71,6 +71,7 @@ module API
       expose :avatar_url
       expose :star_count, :forks_count
       expose :open_issues_count, if: lambda { |project, options| project.issues_enabled? && project.default_issues_tracker? }
+      expose :runners_token, if: lambda { |_project, options| options[:user_can_admin_project] }
     end
 
     class ProjectMember < UserBasic

lib/api/projects.rb

@@ -69,7 +69,8 @@ module API
       # Example Request:
       #   GET /projects/:id
       get ":id" do
-        present user_project, with: Entities::ProjectWithAccess, user: current_user
+        present user_project, with: Entities::ProjectWithAccess, user: current_user,
+                              user_can_admin_project: can?(current_user, :admin_project, user_project)
       end
 
       # Get events for a single project
@@ -118,7 +119,8 @@ module API
         attrs = map_public_to_visibility_level(attrs)
         @project = ::Projects::CreateService.new(current_user, attrs).execute
         if @project.saved?
-          present @project, with: Entities::Project
+          present @project, with: Entities::Project,
+                            user_can_admin_project: can?(current_user, :admin_project, @project)
         else
           if @project.errors[:limit_reached].present?
             error!(@project.errors[:limit_reached], 403)
@@ -163,7 +165,8 @@ module API
         attrs = map_public_to_visibility_level(attrs)
         @project = ::Projects::CreateService.new(user, attrs).execute
         if @project.saved?
-          present @project, with: Entities::Project
+          present @project, with: Entities::Project,
+                            user_can_admin_project: can?(current_user, :admin_project, @project)
         else
           render_validation_error!(@project)
         end
@@ -182,8 +185,9 @@ module API
         if @forked_project.errors.any?
           conflict!(@forked_project.errors.messages)
         else
-          present @forked_project, with: Entities::Project
-        end
+          present @forked_project, with: Entities::Project,
+                                   user_can_admin_project: can?(current_user, :admin_project, @forked_project)
+         end
       end
 
       # Update an existing project
@@ -229,7 +233,8 @@ module API
         if user_project.errors.any?
           render_validation_error!(user_project)
         else
-          present user_project, with: Entities::Project
+          present user_project, with: Entities::Project,
+                                user_can_admin_project: can?(current_user, :admin_project, user_project)
         end
       end
 

lib/banzai/filter/reference_filter.rb

@@ -133,7 +133,7 @@ module Banzai
 
           next unless link && text
 
-          link = URI.decode(link)
+          link = CGI.unescape(link)
           # Ignore ending punctionation like periods or commas
           next unless link == text && text =~ /\A#{pattern}/
 
@@ -170,7 +170,7 @@ module Banzai
           text = node.text
 
           next unless link && text
-          link = URI.decode(link)
+          link = CGI.unescape(link)
           next unless link && link =~ /\A#{pattern}\z/
 
           html = yield link, text

lib/gitlab/gitlab_import/importer.rb

@@ -12,7 +12,7 @@ module Gitlab
       end
 
       def execute
-        project_identifier = URI.encode(project.import_source, '/')
+        project_identifier = CGI.escape(project.import_source, '/')
 
         #Issues && Comments
         issues = client.issues(project_identifier)

lib/gitlab/metrics.rb

@@ -13,7 +13,8 @@ module Gitlab
         timeout:               current_application_settings[:metrics_timeout],
         method_call_threshold: current_application_settings[:metrics_method_call_threshold],
         host:                  current_application_settings[:metrics_host],
-        port:                  current_application_settings[:metrics_port]
+        port:                  current_application_settings[:metrics_port],
+        sample_interval:       current_application_settings[:metrics_sample_interval] || 15
       }
     end
 

lib/gitlab/metrics/sampler.rb

@@ -7,9 +7,14 @@ module Gitlab
     # statistics, etc.
     class Sampler
       # interval - The sampling interval in seconds.
-      def initialize(interval = 15)
-        @interval = interval
-        @metrics  = []
+      def initialize(interval = Metrics.settings[:sample_interval])
+        interval_half = interval.to_f / 2
+
+        @interval       = interval
+        @interval_steps = (-interval_half..interval_half).step(0.1).to_a
+        @last_step      = nil
+
+        @metrics = []
 
         @last_minor_gc = Delta.new(GC.stat[:minor_gc_count])
         @last_major_gc = Delta.new(GC.stat[:major_gc_count])
@@ -26,7 +31,7 @@ module Gitlab
           Thread.current.abort_on_exception = true
 
           loop do
-            sleep(@interval)
+            sleep(sleep_interval)
 
             sample
           end
@@ -102,6 +107,23 @@ module Gitlab
       def sidekiq?
         Sidekiq.server?
       end
+
+      # Returns the sleep interval with a random adjustment.
+      #
+      # The random adjustment is put in place to ensure we:
+      #
+      # 1. Don't generate samples at the exact same interval every time (thus
+      #    potentially missing anything that happens in between samples).
+      # 2. Don't sample data at the same interval two times in a row.
+      def sleep_interval
+        while step = @interval_steps.sample
+          if step != @last_step
+            @last_step = step
+
+            return @interval + @last_step
+          end
+        end
+      end
     end
   end
 end

spec/lib/gitlab/metrics/sampler_spec.rb

@@ -9,7 +9,7 @@ describe Gitlab::Metrics::Sampler do
 
   describe '#start' do
     it 'gathers a sample at a given interval' do
-      expect(sampler).to receive(:sleep).with(5)
+      expect(sampler).to receive(:sleep).with(a_kind_of(Numeric))
       expect(sampler).to receive(:sample)
       expect(sampler).to receive(:loop).and_yield
 
@@ -116,4 +116,24 @@ describe Gitlab::Metrics::Sampler do
       sampler.add_metric('cats', value: 10)
     end
   end
+
+  describe '#sleep_interval' do
+    it 'returns a Numeric' do
+      expect(sampler.sleep_interval).to be_a_kind_of(Numeric)
+    end
+
+    # Testing random behaviour is very hard, so treat this test as a basic smoke
+    # test instead of a very accurate behaviour/unit test.
+    it 'does not return the same interval twice in a row' do
+      last = nil
+
+      100.times do
+        interval = sampler.sleep_interval
+
+        expect(interval).to_not eq(last)
+
+        last = interval
+      end
+    end
+  end
 end