Merge branch 'fix/private-references' into 'master'

Show referenced MRs & Issues only when the current viewer can access them

This addresses both issues identified in #6066.

## The private MR by user `remy2` with a note referencing to a public issue

![Screen_Shot_2016-01-12_at_16.45.02](/uploads/c245ec2c1fdea1f9ba05183c24e142d9/Screen_Shot_2016-01-12_at_16.45.02.png)

---

## The public issue viewed by user `remy` **who doesn't have access to `remy2/private-project`** before the fix

![Screen_Shot_2016-01-12_at_18.14.50](/uploads/8db5580e803f5bddd6cb935233c579a0/Screen_Shot_2016-01-12_at_18.14.50.png)

---

## The public issue viewed by user `remy` **who doesn't have access to `remy2/private-project`** with the fix

![Screen_Shot_2016-01-13_at_12.02.32](/uploads/cb199f7b78191fba486a11412412e307/Screen_Shot_2016-01-13_at_12.02.32.png)

---

## The public issue viewed by user `remy2` with the fix (no change)

![Screen_Shot_2016-01-13_at_11.54.06](/uploads/ddece590d69f597a95559beddcd36660/Screen_Shot_2016-01-13_at_11.54.06.png)


See merge request !2405

2 files changed, 76 insertions, 0 deletions

diff --git a/spec/models/note_spec.rb b/spec/models/note_spec.rb
index 151a29e974b..9182b42661d 100644
--- a/spec/models/note_spec.rb
+++ b/spec/models/note_spec.rb
@@ -178,6 +178,30 @@ describe Note, models: true do
     end
   end
 
+  describe "cross_reference_not_visible_for?" do
+    let(:private_user)    { create(:user) }
+    let(:private_project) { create(:project, namespace: private_user.namespace).tap { |p| p.team << [private_user, :master] } }
+    let(:private_issue)   { create(:issue, project: private_project) }
+
+    let(:ext_proj)  { create(:project, :public) }
+    let(:ext_issue) { create(:issue, project: ext_proj) }
+
+    let(:note) do
+      create :note,
+        noteable: ext_issue, project: ext_proj,
+        note: "mentioned in issue #{private_issue.to_reference(ext_proj)}",
+        system: true
+    end
+
+    it "returns true" do
+      expect(note.cross_reference_not_visible_for?(ext_issue.author)).to be_truthy
+    end
+
+    it "returns false" do
+      expect(note.cross_reference_not_visible_for?(private_user)).to be_falsy
+    end
+  end
+
   describe "set_award!" do
     let(:issue) { create :issue }
 
diff --git a/spec/requests/api/notes_spec.rb b/spec/requests/api/notes_spec.rb
index 8b177af4689..d8bbd107269 100644
--- a/spec/requests/api/notes_spec.rb
+++ b/spec/requests/api/notes_spec.rb
@@ -10,6 +10,25 @@ describe API::API, api: true  do
   let!(:issue_note) { create(:note, noteable: issue, project: project, author: user) }
   let!(:merge_request_note) { create(:note, noteable: merge_request, project: project, author: user) }
   let!(:snippet_note) { create(:note, noteable: snippet, project: project, author: user) }
+
+  # For testing the cross-reference of a private issue in a public issue
+  let(:private_user)    { create(:user) }
+  let(:private_project) do
+    create(:project, namespace: private_user.namespace).
+    tap { |p| p.team << [private_user, :master] }
+  end
+  let(:private_issue)    { create(:issue, project: private_project) }
+
+  let(:ext_proj)  { create(:project, :public) }
+  let(:ext_issue) { create(:issue, project: ext_proj) }
+
+  let!(:cross_reference_note) do
+    create :note,
+    noteable: ext_issue, project: ext_proj,
+    note: "mentioned in issue #{private_issue.to_reference(ext_proj)}",
+    system: true
+  end
+
   before { project.team << [user, :reporter] }
 
   describe "GET /projects/:id/noteable/:noteable_id/notes" do
@@ -25,6 +44,24 @@ describe API::API, api: true  do
         get api("/projects/#{project.id}/issues/123/notes", user)
         expect(response.status).to eq(404)
       end
+
+      context "that references a private issue" do
+        it "should return an empty array" do
+          get api("/projects/#{ext_proj.id}/issues/#{ext_issue.id}/notes", user)
+          expect(response.status).to eq(200)
+          expect(json_response).to be_an Array
+          expect(json_response).to be_empty
+        end
+
+        context "and current user can view the note" do
+          it "should return an empty array" do
+            get api("/projects/#{ext_proj.id}/issues/#{ext_issue.id}/notes", private_user)
+            expect(response.status).to eq(200)
+            expect(json_response).to be_an Array
+            expect(json_response.first['body']).to eq(cross_reference_note.note)
+          end
+        end
+      end
     end
 
     context "when noteable is a Snippet" do
@@ -68,6 +105,21 @@ describe API::API, api: true  do
         get api("/projects/#{project.id}/issues/#{issue.id}/notes/123", user)
         expect(response.status).to eq(404)
       end
+
+      context "that references a private issue" do
+        it "should return a 404 error" do
+          get api("/projects/#{ext_proj.id}/issues/#{ext_issue.id}/notes/#{cross_reference_note.id}", user)
+          expect(response.status).to eq(404)
+        end
+
+        context "and current user can view the note" do
+          it "should return an issue note by id" do
+            get api("/projects/#{ext_proj.id}/issues/#{ext_issue.id}/notes/#{cross_reference_note.id}", private_user)
+            expect(response.status).to eq(200)
+            expect(json_response['body']).to eq(cross_reference_note.note)
+          end
+        end
+      end
     end
 
     context "when noteable is a Snippet" do