Reference filters ✨

Commit ranges, commits, external issues, issues, labels, merge requests,
snippets, users.

app/helpers/issues_helper.rb

@@ -108,4 +108,6 @@ module IssuesHelper
       xml.summary issue.title
     end
   end
+
+  module_function :url_for_issue, :title_for_issue
 end

app/helpers/labels_helper.rb

@@ -7,9 +7,13 @@ module LabelsHelper
     label_color = label.color || Label::DEFAULT_COLOR
     text_color = text_color_for_bg(label_color)
 
-    content_tag :span, class: 'label color-label', style: "background-color:#{label_color};color:#{text_color}" do
-      label.name
-    end
+    # Intentionally not using content_tag here so that this method can be called
+    # by LabelReferenceFilter
+    span = %(<span class="label color-label") +
+      %( style="background-color: #{label_color}; color: #{text_color}">) +
+      label.name + '</span>'
+
+    span.html_safe
   end
 
   def suggested_colors
@@ -42,13 +46,15 @@ module LabelsHelper
     r, g, b = bg_color.slice(1,7).scan(/.{2}/).map(&:hex)
 
     if (r + g + b) > 500
-      "#333"
+      '#333333'
     else
-      "#FFF"
+      '#FFFFFF'
     end
   end
 
   def project_labels_options(project)
     options_from_collection_for_select(project.labels, 'name', 'name', params[:label_name])
   end
+
+  module_function :render_colored_label, :text_color_for_bg
 end

lib/gitlab/markdown/commit_range_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces commit range references with links. References
+    # within <pre>, <code>, <a>, and <style> elements are ignored.
+    #
+    # This filter supports cross-project references.
+    #
+    # Context options:
+    #   :project (required) - Current project, ignored when reference is
+    #                         cross-project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class CommitRangeReferenceFilter < HTML::Pipeline::Filter
+      include CrossProjectReference
+
+      # Public: Find commit range references in text
+      #
+      #   CommitRangeReferenceFilter.references_in(text) do |match, commit_range, project_ref|
+      #     "<a href=...>#{commit_range}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match, the String commit range, and an optional String
+      # of the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(COMMIT_RANGE_PATTERN) do |match|
+          yield match, $~[:commit_range], $~[:project]
+        end
+      end
+
+      # Pattern used to extract commit range references from text
+      #
+      # The beginning and ending SHA1 sums can be between 6 and 40 hex
+      # characters, and the range selection can be double- or triple-dot.
+      #
+      # This pattern supports cross-project references.
+      COMMIT_RANGE_PATTERN = /(#{PROJECT_PATTERN}@)?(?<commit_range>\h{6,40}\.{2,3}\h{6,40})/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(COMMIT_RANGE_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = commit_range_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      # Replace commit range references in text with links to compare the commit
+      # ranges.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with commit range references replaced with links. All
+      # links have `gfm` and `gfm-commit_range` class names attached for
+      # styling.
+      def commit_range_link_filter(text)
+        self.class.references_in(text) do |match, commit_range, project_ref|
+          project = self.project_from_ref(project_ref)
+
+          from_id, to_id = split_commit_range(commit_range)
+
+          if valid_range?(project, from_id, to_id)
+            url = url_for_commit_range(project, from_id, to_id)
+
+            title = "Commits #{from_id} through #{to_id}"
+            klass = "gfm gfm-commit_range #{context[:reference_class]}".strip
+
+            project_ref += '@' if project_ref
+
+            %(<a href="#{url}"
+                 title="#{title}"
+                 class="#{klass}">#{project_ref}#{commit_range}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def validate
+        needs :project
+      end
+
+      def split_commit_range(range)
+        from_id, to_id = range.split(/\.{2,3}/, 2)
+        from_id << "^" if range !~ /\.{3}/
+
+        [from_id, to_id]
+      end
+
+      def valid_range?(project, from_id, to_id)
+        project.valid_repo? &&
+          project.repository.commit(from_id) &&
+          project.repository.commit(to_id)
+      end
+
+      def url_for_commit_range(project, from_id, to_id)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_compare_url(project.namespace, project,
+                                        from: from_id, to: to_id,
+                                        only_path: context[:only_path])
+      end
+
+      def project
+        context[:project]
+      end
+    end
+  end
+end

lib/gitlab/markdown/commit_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces commit references with links. References within
+    # <pre>, <code>, <a>, and <style> elements are ignored.
+    #
+    # This filter supports cross-project references.
+    #
+    # Context options:
+    #   :project (required) - Current project, ignored when reference is
+    #                         cross-project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class CommitReferenceFilter < HTML::Pipeline::Filter
+      include CrossProjectReference
+
+      # Public: Find commit references in text
+      #
+      #   CommitReferenceFilter.references_in(text) do |match, commit, project_ref|
+      #     "<a href=...>#{commit}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match, the String commit identifier, and an optional
+      # String of the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(COMMIT_PATTERN) do |match|
+          yield match, $~[:commit], $~[:project]
+        end
+      end
+
+      # Pattern used to extract commit references from text
+      #
+      # The SHA1 sum can be between 6 and 40 hex characters.
+      #
+      # This pattern supports cross-project references.
+      COMMIT_PATTERN = /(#{PROJECT_PATTERN}@)?(?<commit>\h{6,40})/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(COMMIT_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = commit_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace commit references in text with links to the commit specified.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with commit references replaced with links. All links
+      # have `gfm` and `gfm-commit` class names attached for styling.
+      def commit_link_filter(text)
+        self.class.references_in(text) do |match, commit_ref, project_ref|
+          project = self.project_from_ref(project_ref)
+
+          if project.valid_repo? && commit = project.repository.commit(commit_ref)
+            url = url_for_commit(project, commit)
+
+            title = commit.link_title
+            klass = "gfm gfm-commit #{context[:reference_class]}".strip
+
+            project_ref += '@' if project_ref
+
+            %(<a href="#{url}"
+                 title="#{title}"
+                 class="#{klass}">#{project_ref}#{commit_ref}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def url_for_commit(project, commit)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_commit_url(project.namespace, project, commit,
+                                        only_path: context[:only_path])
+      end
+
+      def project
+        context[:project]
+      end
+    end
+  end
+end

lib/gitlab/markdown/cross_project_reference.rb

+module Gitlab
+  module Markdown
+    # Includes shared code for reference filters that support an optional
+    # cross-project reference.
+    module CrossProjectReference
+      NAMING_PATTERN  = Gitlab::Regex::NAMESPACE_REGEX_STR
+      PROJECT_PATTERN = "(?<project>#{NAMING_PATTERN}/#{NAMING_PATTERN})"
+
+      # Given a cross-project reference string, get the Project record
+      #
+      # If no valid reference is given, returns the `:project` value for the
+      # current context.
+      #
+      # ref - String reference.
+      #
+      # Returns a Project
+      def project_from_ref(ref)
+        if ref && other = Project.find_with_namespace(ref)
+          other
+        else
+          context[:project]
+        end
+      end
+    end
+  end
+end

lib/gitlab/markdown/external_issue_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces external issue tracker references with links.
+    # References within <pre>, <code>, <a>, and <style> elements are ignored.
+    #
+    # Context options:
+    #   :project (required) - Current project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class ExternalIssueReferenceFilter < HTML::Pipeline::Filter
+      # Public: Find `JIRA-123` issue references in text
+      #
+      #   ExternalIssueReferenceFilter.references_in(text) do |match, issue|
+      #     "<a href=...>##{issue}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match and the String issue reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(ISSUE_PATTERN) do |match|
+          yield match, $~[:issue]
+        end
+      end
+
+      # Pattern used to extract `JIRA-123` issue references from text
+      ISSUE_PATTERN = /(?<issue>([A-Z\-]+-)\d+)/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next if project.default_issues_tracker?
+          next unless content.match(ISSUE_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = issue_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace `JIRA-123` issue references in text with links to the referenced
+      # issue's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with `JIRA-123` references replaced with links. All
+      # links have `gfm` and `gfm-issue` class names attached for styling.
+      def issue_link_filter(text)
+        project = context[:project]
+
+        self.class.references_in(text) do |match, issue|
+          url = url_for_issue(issue, project, only_path: context[:only_path])
+
+          title = "Issue in #{project.external_issue_tracker.title}"
+          klass = "gfm gfm-issue #{context[:reference_class]}".strip
+
+          %(<a href="#{url}"
+               title="#{title}"
+               class="#{klass}">#{issue}</a>)
+        end
+      end
+
+      # TODO (rspeicher): Duplicates IssueReferenceFilter
+      def project
+        context[:project]
+      end
+
+      # TODO (rspeicher): Duplicates IssueReferenceFilter
+      def url_for_issue(*args)
+        IssuesHelper.url_for_issue(*args)
+      end
+    end
+  end
+end

lib/gitlab/markdown/issue_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces issue references with links. References within
+    # <pre>, <code>, <a>, and <style> elements are ignored. References to issues
+    # that do not exist are ignored.
+    #
+    # This filter supports cross-project references.
+    #
+    # Context options:
+    #   :project (required) - Current project, ignored when reference is
+    #                         cross-project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class IssueReferenceFilter < HTML::Pipeline::Filter
+      include CrossProjectReference
+
+      # Public: Find `#123` issue references in text
+      #
+      #   IssueReferenceFilter.references_in(text) do |match, issue, project_ref|
+      #     "<a href=...>##{issue}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match, the Integer issue ID, and an optional String of
+      # the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(ISSUE_PATTERN) do |match|
+          yield match, $~[:issue].to_i, $~[:project]
+        end
+      end
+
+      # Pattern used to extract `#123` issue references from text
+      #
+      # This pattern supports cross-project references.
+      ISSUE_PATTERN = /#{PROJECT_PATTERN}?\#(?<issue>([a-zA-Z\-]+-)?\d+)/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless project.default_issues_tracker?
+          next unless content.match(ISSUE_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = issue_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace `#123` issue references in text with links to the referenced
+      # issue's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with `#123` references replaced with links. All links
+      # have `gfm` and `gfm-issue` class names attached for styling.
+      def issue_link_filter(text)
+        self.class.references_in(text) do |match, issue, project_ref|
+          project = self.project_from_ref(project_ref)
+
+          if project.issue_exists?(issue)
+            # FIXME: Ugly
+            url = url_for_issue(issue, project, only_path: context[:only_path])
+
+            title = "Issue: #{title_for_issue(issue, project)}"
+            klass = "gfm gfm-issue #{context[:reference_class]}".strip
+
+            %(<a href="#{url}"
+                 title="#{title}"
+                 class="#{klass}">#{project_ref}##{issue}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def project
+        context[:project]
+      end
+
+      def url_for_issue(*args)
+        IssuesHelper.url_for_issue(*args)
+      end
+
+      def title_for_issue(*args)
+        IssuesHelper.title_for_issue(*args)
+      end
+    end
+  end
+end

lib/gitlab/markdown/label_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces label references with links. References within
+    # <pre>, <code>, <a>, and <style> elements are ignored.
+    #
+    # Context options:
+    #   :project (required) - Current project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class LabelReferenceFilter < HTML::Pipeline::Filter
+      # Public: Find label references in text
+      #
+      #   LabelReferenceFilter.references_in(text) do |match, label|
+      #     "<a href=...>#{label}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match and the Integer label ID.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(LABEL_PATTERN) do |match|
+          yield match, $~[:label].to_i
+        end
+      end
+
+      # Pattern used to extract label references from text
+      #
+      # This pattern supports cross-project references.
+      LABEL_PATTERN = /~(?<label>\d+)/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(LABEL_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = label_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace label references in text with links to the label specified.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with label references replaced with links. All links
+      # have `gfm` and `gfm-label` class names attached for styling.
+      def label_link_filter(text)
+        project = context[:project]
+
+        self.class.references_in(text) do |match, id|
+          if label = project.labels.find_by(id: id)
+            url = url_for_label(project, label)
+
+            klass = "gfm gfm-label #{context[:reference_class]}".strip
+
+            %(<a href="#{url}" class="#{klass}">#{render_colored_label(label)}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def url_for_label(project, label)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_issues_path(project.namespace, project,
+                                        label_name: label.name,
+                                        only_path: context[:only_path])
+      end
+
+      def render_colored_label(label)
+        LabelsHelper.render_colored_label(label)
+      end
+
+      def project
+        context[:project]
+      end
+    end
+  end
+end

lib/gitlab/markdown/merge_request_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces merge request references with links. References
+    # within <pre>, <code>, <a>, and <style> elements are ignored. References to
+    # merge requests that do not exist are ignored.
+    #
+    # This filter supports cross-project references.
+    #
+    # Context options:
+    #   :project (required) - Current project, ignored when reference is
+    #                         cross-project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class MergeRequestReferenceFilter < HTML::Pipeline::Filter
+      include CrossProjectReference
+
+      # Public: Find `!123` merge request references in text
+      #
+      #   MergeRequestReferenceFilter.references_in(text) do |match, merge_request, project_ref|
+      #     "<a href=...>##{merge_request}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match, the Integer merge request ID, and an optional
+      # String of the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(MERGE_REQUEST_PATTERN) do |match|
+          yield match, $~[:merge_request].to_i, $~[:project]
+        end
+      end
+
+      # Pattern used to extract `!123` merge request references from text
+      #
+      # This pattern supports cross-project references.
+      MERGE_REQUEST_PATTERN = /#{PROJECT_PATTERN}?!(?<merge_request>\d+)/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(MERGE_REQUEST_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = merge_request_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace `!123` merge request references in text with links to the
+      # referenced merge request's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with `!123` references replaced with links. All links
+      # have `gfm` and `gfm-merge_request` class names attached for styling.
+      def merge_request_link_filter(text)
+        self.class.references_in(text) do |match, id, project_ref|
+          project = self.project_from_ref(project_ref)
+
+          if merge_request = project.merge_requests.find_by(iid: id)
+            title = "Merge Request: #{merge_request.title}"
+            klass = "gfm gfm-merge_request #{context[:reference_class]}".strip
+
+            url = url_for_merge_request(merge_request, project)
+
+            %(<a href="#{url}"
+                 title="#{title}"
+                 class="#{klass}">#{project_ref}!#{id}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def project
+        context[:project]
+      end
+
+      # TODO (rspeicher): Cleanup
+      def url_for_merge_request(mr, project)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_merge_request_url(project.namespace, project, mr,
+                                            only_path: context[:only_path])
+      end
+    end
+  end
+end

lib/gitlab/markdown/snippet_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces snippet references with links. References within
+    # <pre>, <code>, <a>, and <style> elements are ignored. References to
+    # snippets that do not exist are ignored.
+    #
+    # Context options:
+    #   :project (required) - Current project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class SnippetReferenceFilter < HTML::Pipeline::Filter
+      # Public: Find `$123` snippet references in text
+      #
+      #   SnippetReferenceFilter.references_in(text) do |match, snippet|
+      #     "<a href=...>$#{snippet}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match and the Integer snippet ID.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(SNIPPET_PATTERN) do |match|
+          yield match, $~[:snippet].to_i
+        end
+      end
+
+      # Pattern used to extract `$123` snippet references from text
+      SNIPPET_PATTERN = /\$(?<snippet>\d+)/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(SNIPPET_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = snippet_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace `$123` snippet references in text with links to the referenced
+      # snippets's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with `$123` references replaced with links. All links
+      # have `gfm` and `gfm-snippet` class names attached for styling.
+      def snippet_link_filter(text)
+        project = context[:project]
+
+        self.class.references_in(text) do |match, id|
+          if snippet = project.snippets.find_by(id: id)
+            title = "Snippet: #{snippet.title}"
+            klass = "gfm gfm-snippet #{context[:reference_class]}".strip
+
+            url = url_for_snippet(snippet, project)
+
+            %(<a href="#{url}"
+                 title="#{title}"
+                 class="#{klass}">$#{id}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def project
+        context[:project]
+      end
+
+      def url_for_snippet(snippet, project)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_snippet_url(project.namespace, project, snippet,
+                                        only_path: context[:only_path])
+      end
+    end
+  end
+end

lib/gitlab/markdown/user_reference_filter.rb

+require 'html/pipeline'
+
+module Gitlab
+  module Markdown
+    # HTML filter that replaces user or group references with links. References
+    # within <pre>, <code>, <a>, and <style> elements are ignored.
+    #
+    # A special `@all` reference is also supported.
+    #
+    # Context options:
+    #   :project (required) - Current project.
+    #   :reference_class    - Custom CSS class added to reference links.
+    #   :only_path          - Generate path-only links.
+    #
+    class UserReferenceFilter < HTML::Pipeline::Filter
+      # Public: Find `@user` user references in text
+      #
+      #   UserReferenceFilter.references_in(text) do |match, username|
+      #     "<a href=...>@#{user}</a>"
+      #   end
+      #
+      # text - String text to search.
+      #
+      # Yields the String match, and the String user name.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(USER_PATTERN) do |match|
+          yield match, $~[:user]
+        end
+      end
+
+      # Pattern used to extract `@user` user references from text
+      USER_PATTERN = /@(?<user>#{Gitlab::Regex::NAMESPACE_REGEX_STR})/
+
+      # Don't look for references in text nodes that are children of these
+      # elements.
+      IGNORE_PARENTS = %w(pre code a style).to_set
+
+      def call
+        doc.search('text()').each do |node|
+          content = node.to_html
+
+          next if project.nil?
+          next unless content.match(USER_PATTERN)
+          next if has_ancestor?(node, IGNORE_PARENTS)
+
+          html = user_link_filter(content)
+
+          next if html == content
+
+          node.replace(html)
+        end
+
+        doc
+      end
+
+      def validate
+        needs :project
+      end
+
+      # Replace `@user` user references in text with links to the referenced
+      # user's profile page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with `@user` references replaced with links. All links
+      # have `gfm` and `gfm-project_member` class names attached for styling.
+      def user_link_filter(text)
+        project = context[:project]
+
+        self.class.references_in(text) do |match, user|
+          klass = "gfm gfm-project_member #{context[:reference_class]}".strip
+
+          if user == 'all'
+            url = link_to_all(project)
+
+            %(<a href="#{url}" class="#{klass}">@#{user}</a>)
+          elsif namespace = Namespace.find_by(path: user)
+            if namespace.is_a?(Group)
+              url = group_url(user, only_path: context[:only_path])
+            else
+              url = user_url(user, only_path: context[:only_path])
+            end
+
+            %(<a href="#{url}" class="#{klass}">@#{user}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def project
+        context[:project]
+      end
+
+      # TODO (rspeicher): Cleanup
+      def group_url(*args)
+        h = Rails.application.routes.url_helpers
+        h.group_url(*args)
+      end
+
+      # TODO (rspeicher): Cleanup
+      def user_url(*args)
+        h = Rails.application.routes.url_helpers
+        h.user_url(*args)
+      end
+
+      # TODO (rspeicher): Cleanup
+      def link_to_all(project)
+        h = Rails.application.routes.url_helpers
+        h.namespace_project_url(project.namespace, project,
+                                only_path: context[:only_path])
+      end
+    end
+  end
+end

spec/helpers/gitlab_markdown_helper_spec.rb

@@ -348,56 +348,6 @@ describe GitlabMarkdownHelper do
       end
     end
 
-    describe "referencing a Jira issue" do
-      let(:actual)   { "Reference to JIRA-#{issue.iid}" }
-      let(:expected) { "http://jira.example/browse/JIRA-#{issue.iid}" }
-      let(:reference) { "JIRA-#{issue.iid}" }
-
-      before do
-        jira = @project.create_jira_service if @project.jira_service.nil?
-        properties = {"title"=>"JIRA tracker", "project_url"=>"http://jira.example/issues/?jql=project=A", "issues_url"=>"http://jira.example/browse/:id", "new_issue_url"=>"http://jira.example/secure/CreateIssue.jspa"}
-        jira.update_attributes(properties: properties, active: true)
-      end
-
-      after do
-        @project.jira_service.destroy! unless @project.jira_service.nil?
-      end
-
-      it "should link using a valid id" do
-        expect(gfm(actual)).to match(expected)
-      end
-
-      it "should link with adjacent text" do
-        # Wrap the reference in parenthesis
-        expect(gfm(actual.gsub(reference, "(#{reference})"))).to match(expected)
-
-        # Append some text to the end of the reference
-        expect(gfm(actual.gsub(reference, "#{reference}, right?"))).
-          to match(expected)
-      end
-
-      it "should keep whitespace intact" do
-        actual   = "Referenced #{reference} already."
-        expected = /Referenced <a.+>[^\s]+<\/a> already/
-        expect(gfm(actual)).to match(expected)
-      end
-
-      it "should not link with an invalid id" do
-        # Modify the reference string so it's still parsed, but is invalid
-        invalid_reference = actual.gsub(/(\d+)$/, "r45")
-        expect(gfm(invalid_reference)).to eq(invalid_reference)
-      end
-
-      it "should include a title attribute" do
-        title = "Issue in JIRA tracker"
-        expect(gfm(actual)).to match(/title="#{title}"/)
-      end
-
-      it "should include standard gfm classes" do
-        expect(gfm(actual)).to match(/class="\s?gfm gfm-issue\s?"/)
-      end
-    end
-
     describe "referencing a merge request" do
       let(:object)    { merge_request }
       let(:reference) { "!#{merge_request.iid}" }
@@ -659,7 +609,7 @@ describe GitlabMarkdownHelper do
     end
 
     it "should leave ref-like href of 'manual' links untouched" do
-      expect(markdown("why not [inspect !#{merge_request.iid}](http://example.tld/#!#{merge_request.iid})")).to eq("<p>why not <a href=\"http://example.tld/#!#{merge_request.iid}\">inspect </a><a class=\"gfm gfm-merge_request \" href=\"#{namespace_project_merge_request_path(project.namespace, project, merge_request)}\" title=\"Merge Request: #{merge_request.title}\">!#{merge_request.iid}</a><a href=\"http://example.tld/#!#{merge_request.iid}\"></a></p>\n")
+      expect(markdown("why not [inspect !#{merge_request.iid}](http://example.tld/#!#{merge_request.iid})")).to eq("<p>why not <a href=\"http://example.tld/#!#{merge_request.iid}\">inspect </a><a href=\"#{namespace_project_merge_request_path(project.namespace, project, merge_request)}\" title=\"Merge Request: #{merge_request.title}\" class=\"gfm gfm-merge_request \">!#{merge_request.iid}</a><a href=\"http://example.tld/#!#{merge_request.iid}\"></a></p>\n")
     end
 
     it "should leave ref-like src of images untouched" do

spec/helpers/labels_helper_spec.rb

 require 'spec_helper'
 
 describe LabelsHelper do
-  it { expect(text_color_for_bg('#EEEEEE')).to eq('#333') }
-  it { expect(text_color_for_bg('#222E2E')).to eq('#FFF') }
+  it { expect(text_color_for_bg('#EEEEEE')).to eq('#333333') }
+  it { expect(text_color_for_bg('#222E2E')).to eq('#FFFFFF') }
 end

spec/lib/gitlab/markdown/commit_range_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe CommitRangeReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project) { create(:project) }
+    let(:commit1) { project.repository.commit }
+    let(:commit2) { project.repository.commit("HEAD~2") }
+
+    it 'requires project context' do
+      expect { described_class.call('Commit Range 1c002d..d200c1', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Commit Range #{commit1.id}..#{commit2.id}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    context 'internal reference' do
+      let(:reference) { "#{commit1.id}...#{commit2.id}" }
+      let(:reference2) { "#{commit1.id}..#{commit2.id}" }
+
+      it 'links to a valid two-dot reference' do
+        doc = filter("See #{reference2}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq urls.namespace_project_compare_url(project.namespace, project, from: "#{commit1.id}^", to: commit2.id)
+      end
+
+      it 'links to a valid three-dot reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq urls.namespace_project_compare_url(project.namespace, project, from: commit1.id, to: commit2.id)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("See (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid issue IDs' do
+        exp = act = "See #{commit1.id.reverse}...#{commit2.id}"
+
+        expect(project).to receive(:valid_repo?).and_return(true)
+        expect(project.repository).to receive(:commit).with(commit1.id.reverse)
+        expect(filter(act).to_html).to eq exp
+      end
+
+      it 'includes a title attribute' do
+        doc = filter("See #{reference}")
+        expect(doc.css('a').first.attr('title')).to eq "Commits #{commit1.id} through #{commit2.id}"
+      end
+
+      it 'includes default classes' do
+        doc = filter("See #{reference}")
+        expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-commit_range'
+      end
+
+      it 'includes an optional custom class' do
+        doc = filter("See #{reference}", reference_class: 'custom')
+        expect(doc.css('a').first.attr('class')).to include 'custom'
+      end
+
+      it 'supports an :only_path option' do
+        doc = filter("See #{reference}", only_path: true)
+        link = doc.css('a').first.attr('href')
+
+        expect(link).not_to match %r(https?://)
+        expect(link).to eq urls.namespace_project_compare_url(project.namespace, project, from: commit1.id, to: commit2.id, only_path: true)
+      end
+    end
+
+    # TODO (rspeicher): Remove or re-enable
+    # context 'cross-project reference' do
+    #   let(:namespace) { create(:namespace, name: 'cross-reference') }
+    #   let(:project2)  { create(:project, namespace: namespace) }
+    #   let(:commit1)   { project.repository.commit }
+    #   let(:commit2)   { project.repository.commit("HEAD~2") }
+    #   let(:reference) { "#{project2.path_with_namespace}@#{commit.id}" }
+
+    #   it 'links to a valid reference' do
+    #     doc = filter("See #{reference}")
+
+    #     expect(doc.css('a').first.attr('href')).
+    #       to eq urls.namespace_project_commit_url(project2.namespace, project2, commit.id)
+    #   end
+
+    #   it 'links with adjacent text' do
+    #     doc = filter("Fixed (#{reference}.)")
+    #     expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+    #   end
+
+    #   it 'ignores invalid issue IDs on the referenced project' do
+    #     exp = act = "Fixed #{project2.path_with_namespace}##{commit.id.reverse}"
+
+    #     expect(filter(act).to_html).to eq exp
+    #   end
+    # end
+  end
+end

spec/lib/gitlab/markdown/commit_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe CommitReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project) { create(:project) }
+    let(:commit)  { project.repository.commit }
+
+    it 'requires project context' do
+      expect { described_class.call('Commit 1c002d', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Commit #{commit.id}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    context 'internal reference' do
+      let(:reference) { commit.id }
+
+      # Let's test a variety of commit SHA sizes just to be paranoid
+      [6, 8, 12, 18, 20, 32, 40].each do |size|
+        it "links to a valid reference of #{size} characters" do
+          doc = filter("See #{reference[0...size]}")
+
+          expect(doc.css('a').first.text).to eq reference[0...size]
+          expect(doc.css('a').first.attr('href')).
+            to eq urls.namespace_project_commit_url(project.namespace, project, reference)
+        end
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("See (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid issue IDs' do
+        exp = act = "See #{reference.reverse}"
+
+        expect(project).to receive(:valid_repo?).and_return(true)
+        expect(project.repository).to receive(:commit).with(reference.reverse)
+        expect(filter(act).to_html).to eq exp
+      end
+
+      it 'includes a title attribute' do
+        doc = filter("See #{reference}")
+        expect(doc.css('a').first.attr('title')).to eq commit.link_title
+      end
+
+      it 'includes default classes' do
+        doc = filter("See #{reference}")
+        expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-commit'
+      end
+
+      it 'includes an optional custom class' do
+        doc = filter("See #{reference}", reference_class: 'custom')
+        expect(doc.css('a').first.attr('class')).to include 'custom'
+      end
+
+      it 'supports an :only_path context' do
+        doc = filter("See #{reference}", only_path: true)
+        link = doc.css('a').first.attr('href')
+
+        expect(link).not_to match %r(https?://)
+        expect(link).to eq urls.namespace_project_commit_url(project.namespace, project, reference, only_path: true)
+      end
+    end
+
+    context 'cross-project reference' do
+      let(:namespace) { create(:namespace, name: 'cross-reference') }
+      let(:project2)  { create(:project, namespace: namespace) }
+      let(:commit)    { project.repository.commit }
+      let(:reference) { "#{project2.path_with_namespace}@#{commit.id}" }
+
+      it 'links to a valid reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq urls.namespace_project_commit_url(project2.namespace, project2, commit.id)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Fixed (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid issue IDs on the referenced project' do
+        exp = act = "Fixed #{project2.path_with_namespace}##{commit.id.reverse}"
+
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/cross_project_reference_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe CrossProjectReference do
+    include CrossProjectReference
+
+    describe '#project_from_ref' do
+      let(:project) { double('project') }
+
+      it 'returns a project from a valid reference' do
+        expect(Project).to receive(:find_with_namespace).with('cross-reference/foo').and_return(project)
+
+        expect(project_from_ref('cross-reference/foo')).to eq project
+      end
+
+      it 'returns the project from context when reference is invalid' do
+        expect(self).to receive(:context).and_return({project: project})
+
+        expect(project_from_ref('invalid/reference')).to eq project
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/external_issue_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe ExternalIssueReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    def helper
+      IssuesHelper
+    end
+
+    let(:project) { create(:empty_project) }
+    let(:issue)   { double('issue', iid: 123) }
+
+    context 'JIRA issue references' do
+      let(:reference) { "JIRA-#{issue.iid}" }
+
+      before do
+        jira = project.create_jira_service
+
+        props = {
+          'title'         => 'JIRA tracker',
+          'project_url'   => 'http://jira.example/issues/?jql=project=A',
+          'issues_url'    => 'http://jira.example/browse/:id',
+          'new_issue_url' => 'http://jira.example/secure/CreateIssue.jspa'
+        }
+
+        jira.update_attributes(properties: props, active: true)
+      end
+
+      after do
+        project.jira_service.destroy
+      end
+
+      it 'requires project context' do
+        expect { described_class.call('Issue JIRA-123', {}) }.
+          to raise_error(ArgumentError, /:project/)
+      end
+
+      %w(pre code a style).each do |elem|
+        it "ignores valid references contained inside '#{elem}' element" do
+          exp = act = "<#{elem}>Issue JIRA-#{issue.iid}</#{elem}>"
+          expect(filter(act).to_html).to eq exp
+        end
+      end
+
+      it 'ignores valid references when using default tracker' do
+        expect(project).to receive(:default_issues_tracker?).and_return(true)
+
+        exp = act = "Issue #{reference}"
+        expect(filter(act).to_html).to eq exp
+      end
+
+      %w(pre code a style).each do |elem|
+        it "ignores references contained inside '#{elem}' element" do
+          exp = act = "<#{elem}>Issue #{reference}</#{elem}>"
+          expect(filter(act).to_html).to eq exp
+        end
+      end
+
+      it 'links to a valid reference' do
+        doc = filter("Issue #{reference}")
+        expect(doc.css('a').first.attr('href'))
+          .to eq helper.url_for_issue(reference, project)
+      end
+
+      it 'links to the external tracker' do
+        doc = filter("Issue #{reference}")
+        link = doc.css('a').first.attr('href')
+
+        expect(link).to eq "http://jira.example/browse/#{reference}"
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Issue (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{reference}<\/a>\.\)/)
+      end
+
+      it 'includes a title attribute' do
+        doc = filter("Issue #{reference}")
+        expect(doc.css('a').first.attr('title')).to eq "Issue in JIRA tracker"
+      end
+
+      it 'includes default classes' do
+        doc = filter("Issue #{reference}")
+        expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-issue'
+      end
+
+      it 'includes an optional custom class' do
+        doc = filter("Issue #{reference}", reference_class: 'custom')
+        expect(doc.css('a').first.attr('class')).to include 'custom'
+      end
+
+      it 'supports an :only_path context' do
+        doc = filter("Issue #{reference}", only_path: true)
+        link = doc.css('a').first.attr('href')
+
+        expect(link).to eq helper.url_for_issue("#{reference}", project, only_path: true)
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/issue_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe IssueReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    def helper
+      IssuesHelper
+    end
+
+    let(:project) { create(:empty_project) }
+    let(:issue)   { create(:issue, project: project) }
+
+    it 'requires project context' do
+      expect { described_class.call('Issue #123', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    it 'ignores valid references when using non-default tracker' do
+      expect(project).to receive(:default_issues_tracker?).and_return(false)
+
+      exp = act = "Issue ##{issue.iid}"
+      expect(filter(act).to_html).to eq exp
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Issue ##{issue.iid}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    context 'internal reference' do
+      let(:reference) { "##{issue.iid}" }
+
+      it 'links to a valid reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq helper.url_for_issue(issue.iid, project)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Fixed (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid issue IDs' do
+        exp = act = "Fixed ##{issue.iid + 1}"
+
+        expect(project).to receive(:issue_exists?).with(issue.iid + 1)
+        expect(filter(act).to_html).to eq exp
+      end
+
+      it 'includes a title attribute' do
+        doc = filter("Issue #{reference}")
+        expect(doc.css('a').first.attr('title')).to eq "Issue: #{issue.title}"
+      end
+
+      it 'includes default classes' do
+        doc = filter("Issue #{reference}")
+        expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-issue'
+      end
+
+      it 'includes an optional custom class' do
+        doc = filter("Issue #{reference}", reference_class: 'custom')
+        expect(doc.css('a').first.attr('class')).to include 'custom'
+      end
+
+      it 'supports an :only_path context' do
+        doc = filter("Issue #{reference}", only_path: true)
+        link = doc.css('a').first.attr('href')
+
+        expect(link).not_to match %r(https?://)
+        expect(link).to eq helper.url_for_issue(issue.iid, project, only_path: true)
+      end
+    end
+
+    context 'cross-project reference' do
+      let(:namespace) { create(:namespace, name: 'cross-reference') }
+      let(:project2)  { create(:empty_project, namespace: namespace) }
+      let(:issue)     { create(:issue, project: project2) }
+      let(:reference) { "#{project2.path_with_namespace}##{issue.iid}" }
+
+      it 'links to a valid reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq helper.url_for_issue(issue.iid, project2)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Fixed (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid issue IDs on the referenced project' do
+        exp = act = "Fixed #{project2.path_with_namespace}##{issue.iid + 1}"
+
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/label_reference_filter_spec.rb

+require 'spec_helper'
+require 'html/pipeline'
+
+module Gitlab::Markdown
+  describe LabelReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project)   { create(:empty_project) }
+    let(:label)     { create(:label, project: project) }
+    let(:reference) { "~#{label.id}" }
+
+    it 'requires project context' do
+      expect { described_class.call('Label ~123', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Label #{reference}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    it 'links to a valid reference' do
+      doc = filter("See #{reference}")
+
+      expect(doc.css('a').first.attr('href')).to eq urls.
+        namespace_project_issues_url(project.namespace, project, label_name: label.name)
+    end
+
+    it 'links with adjacent text' do
+      doc = filter("Label (#{reference}.)")
+      expect(doc.to_html).to match(%r(\(<a.+><span.+>#{label.name}</span></a>\.\)))
+    end
+
+    it 'ignores invalid label IDs' do
+      exp = act = "Label ~#{label.id + 1}"
+
+      expect(filter(act).to_html).to eq exp
+    end
+
+    it 'includes default classes' do
+      doc = filter("Label #{reference}")
+      expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-label'
+    end
+
+    it 'includes an optional custom class' do
+      doc = filter("Label #{reference}", reference_class: 'custom')
+      expect(doc.css('a').first.attr('class')).to include 'custom'
+    end
+
+    it 'supports an :only_path context' do
+      doc = filter("Label #{reference}", only_path: true)
+      link = doc.css('a').first.attr('href')
+
+      expect(link).not_to match %r(https?://)
+      expect(link).to eq urls.namespace_project_issues_url(project.namespace, project, label_name: label.name, only_path: true)
+    end
+
+    describe 'label span element' do
+      it 'includes default classes' do
+        doc = filter("Label #{reference}")
+        expect(doc.css('a span').first.attr('class')).to eq 'label color-label'
+      end
+
+      it 'includes a style attribute' do
+        doc = filter("Label #{reference}")
+        expect(doc.css('a span').first.attr('style')).to match(/\Abackground-color: #\h{6}; color: #\h{6}\z/)
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/merge_request_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe MergeRequestReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project) { create(:project) }
+    let(:merge)   { create(:merge_request, source_project: project) }
+
+    it 'requires project context' do
+      expect { described_class.call('MergeRequest !123', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Merge !#{merge.iid}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    context 'internal reference' do
+      let(:reference) { "!#{merge.iid}" }
+
+      it 'links to a valid reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).to eq urls.
+          namespace_project_merge_request_url(project.namespace, project, merge)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Merge (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid merge IDs' do
+        exp = act = "Merge !#{merge.iid + 1}"
+
+        expect(filter(act).to_html).to eq exp
+      end
+
+      it 'includes a title attribute' do
+        doc = filter("Merge #{reference}")
+        expect(doc.css('a').first.attr('title')).to eq "Merge Request: #{merge.title}"
+      end
+
+      it 'includes default classes' do
+        doc = filter("Merge #{reference}")
+        expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-merge_request'
+      end
+
+      it 'includes an optional custom class' do
+        doc = filter("Merge #{reference}", reference_class: 'custom')
+        expect(doc.css('a').first.attr('class')).to include 'custom'
+      end
+
+      it 'supports an :only_path context' do
+        doc = filter("Merge #{reference}", only_path: true)
+        link = doc.css('a').first.attr('href')
+
+        expect(link).not_to match %r(https?://)
+        expect(link).to eq urls.namespace_project_merge_request_url(project.namespace, project, merge, only_path: true)
+      end
+    end
+
+    context 'cross-project reference' do
+      let(:namespace) { create(:namespace, name: 'cross-reference') }
+      let(:project2)  { create(:project, namespace: namespace) }
+      let(:merge)     { create(:merge_request, source_project: project2) }
+      let(:reference) { "#{project2.path_with_namespace}!#{merge.iid}" }
+
+      it 'links to a valid reference' do
+        doc = filter("See #{reference}")
+
+        expect(doc.css('a').first.attr('href')).
+          to eq urls.namespace_project_merge_request_url(project2.namespace,
+                                                         project, merge)
+      end
+
+      it 'links with adjacent text' do
+        doc = filter("Merge (#{reference}.)")
+        expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+      end
+
+      it 'ignores invalid merge IDs on the referenced project' do
+        exp = act = "Merge #{project2.path_with_namespace}!#{merge.iid + 1}"
+
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+  end
+end

spec/lib/gitlab/markdown/snippet_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe SnippetReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project)   { create(:empty_project) }
+    let(:snippet)   { create(:project_snippet, project: project) }
+    let(:reference) { "$#{snippet.id}" }
+
+    it 'requires project context' do
+      expect { described_class.call('Snippet $123', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Snippet #{reference}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    it 'links to a valid reference' do
+      doc = filter("See #{reference}")
+
+      expect(doc.css('a').first.attr('href')).to eq urls.
+        namespace_project_snippet_url(project.namespace, project, snippet)
+    end
+
+    it 'links with adjacent text' do
+      doc = filter("Snippet (#{reference}.)")
+      expect(doc.to_html).to match(/\(<a.+>#{Regexp.escape(reference)}<\/a>\.\)/)
+    end
+
+    it 'ignores invalid snippet IDs' do
+      exp = act = "Snippet $#{snippet.id + 1}"
+
+      expect(filter(act).to_html).to eq exp
+    end
+
+    it 'includes a title attribute' do
+      doc = filter("Snippet #{reference}")
+      expect(doc.css('a').first.attr('title')).to eq "Snippet: #{snippet.title}"
+    end
+
+    it 'includes default classes' do
+      doc = filter("Snippet #{reference}")
+      expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-snippet'
+    end
+
+    it 'includes an optional custom class' do
+      doc = filter("Snippet #{reference}", reference_class: 'custom')
+      expect(doc.css('a').first.attr('class')).to include 'custom'
+    end
+
+    it 'supports an :only_path context' do
+      doc = filter("Snippet #{reference}", only_path: true)
+      link = doc.css('a').first.attr('href')
+
+      expect(link).not_to match %r(https?://)
+      expect(link).to eq urls.namespace_project_snippet_url(project.namespace, project, snippet, only_path: true)
+    end
+  end
+end

spec/lib/gitlab/markdown/user_reference_filter_spec.rb

+require 'spec_helper'
+
+module Gitlab::Markdown
+  describe UserReferenceFilter do
+    include ReferenceFilterSpecHelper
+
+    let(:project) { create(:empty_project) }
+    let(:user)    { create(:user) }
+
+    it 'requires project context' do
+      expect { described_class.call('Example @mention', {}) }.
+        to raise_error(ArgumentError, /:project/)
+    end
+
+    it 'ignores invalid users' do
+      exp = act = 'Hey @somebody'
+      expect(filter(act).to_html).to eq(exp)
+    end
+
+    %w(pre code a style).each do |elem|
+      it "ignores valid references contained inside '#{elem}' element" do
+        exp = act = "<#{elem}>Hey @#{user.username}</#{elem}>"
+        expect(filter(act).to_html).to eq exp
+      end
+    end
+
+    context 'mentioning a user' do
+      it 'links to a User' do
+        doc = filter("Hey @#{user.username}")
+        expect(doc.css('a').first.attr('href')).to eq urls.user_url(user)
+      end
+
+      # TODO (rspeicher): This test might be overkill
+      it 'links to a User with a period' do
+        user = create(:user, name: 'alphA.Beta')
+
+        doc = filter("Hey @#{user.username}")
+        expect(doc.css('a').length).to eq 1
+      end
+
+      # TODO (rspeicher): This test might be overkill
+      it 'links to a User with an underscore' do
+        user = create(:user, name: 'ping_pong_king')
+
+        doc = filter("Hey @#{user.username}")
+        expect(doc.css('a').length).to eq 1
+      end
+    end
+
+    it 'links to a Group' do
+      group = create(:group)
+
+      doc = filter("Hey @#{group.name}")
+      expect(doc.css('a').first.attr('href')).to eq urls.group_url(group)
+    end
+
+    it 'links with adjacent text' do
+      doc = filter("Mention me (@#{user.username}.)")
+      expect(doc.to_html).to match(/\(<a.+>@#{user.username}<\/a>\.\)/)
+    end
+
+    it 'supports a special @all mention' do
+      doc = filter("Hey @all")
+      expect(doc.css('a').length).to eq 1
+      expect(doc.css('a').first.attr('href'))
+        .to eq urls.namespace_project_url(project.namespace, project)
+    end
+
+    it 'includes default classes' do
+      doc = filter("Hey @#{user.username}")
+      expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-project_member'
+    end
+
+    it 'includes an optional custom class' do
+      doc = filter("Hey @#{user.username}", reference_class: 'custom')
+      expect(doc.css('a').first.attr('class')).to include 'custom'
+    end
+
+    it 'supports an :only_path context' do
+      doc = filter("Hey @#{user.username}", only_path: true)
+      link = doc.css('a').first.attr('href')
+
+      expect(link).not_to match %r(https?://)
+      expect(link).to eq urls.user_path(user)
+    end
+  end
+end

spec/support/reference_filter_spec_helper.rb

+# Common methods and setup for Gitlab::Markdown reference filter specs
+#
+# Must be included into specs manually
+module ReferenceFilterSpecHelper
+  extend ActiveSupport::Concern
+
+  included do
+    before { set_default_url_options }
+  end
+
+  # Allow *_url helpers to work
+  def set_default_url_options
+    Rails.application.routes.default_url_options = {
+      host: 'example.foo'
+    }
+  end
+
+  # Shortcut to Rails' auto-generated routes helpers, to avoid including the
+  # module
+  def urls
+    Rails.application.routes.url_helpers
+  end
+
+  # Perform `call` on the described class
+  #
+  # Automatically passes the current `project` value to the context if none is
+  # provided.
+  #
+  # html     - String text to pass to the filter's `call` method.
+  # contexts - Hash context for the filter. (default: {project: project})
+  #
+  # Returns the String text returned by the filter's `call` method.
+  def filter(html, contexts = {})
+    contexts.reverse_merge!(project: project)
+    described_class.call(html, contexts)
+  end
+end