Fix project member access for group links

`ProjectTeam#find_member` doesn't take group links into account. It was
used in two places:

1. An admin view - it can stay here.
2. `ProjectTeam#member?`, which is often used to decide if a user has
   access to view something.

This second part broke confidential issues viewing. `IssuesFinder` ends
up delegating to `Project#authorized_for_user?`, which does consider
group links, so users with access to the project via a group link could
see confidential issues on the index page. However, `IssuesPolicy` used
`ProjectTeam#member?`, so the same user couldn't view the issue when
going to it directly.

app/models/project_team.rb

@@ -125,14 +125,8 @@ class ProjectTeam
     max_member_access(user.id) == Gitlab::Access::MASTER
   end
 
-  def member?(user, min_member_access = nil)
+  def member?(user, min_member_access = Gitlab::Access::GUEST)
-    member = !!find_member(user.id)
+    max_member_access(user.id) >= min_member_access
-
-    if min_member_access
-      member && max_member_access(user.id) >= min_member_access
-    else
-      member
-    end
   end
 
   def human_max_access(user_id)

spec/policies/issues_policy_spec.rb

@@ -0,0 +1,163 @@
+require 'spec_helper'
+
+describe IssuePolicy, models: true do
+  let(:guest) { create(:user) }
+  let(:author) { create(:user) }
+  let(:assignee) { create(:user) }
+  let(:reporter) { create(:user) }
+
+  def permissions(user, issue)
+    IssuePolicy.abilities(user, issue).to_set
+  end
+
+  context 'a private project' do
+    let(:non_member) { create(:user) }
+    let(:project) { create(:empty_project, :private) }
+    let(:issue) { create(:issue, project: project, assignee: assignee, author: author) }
+    let(:issue_no_assignee) { create(:issue, project: project) }
+
+    before do
+      project.team << [guest, :guest]
+      project.team << [author, :guest]
+      project.team << [assignee, :guest]
+      project.team << [reporter, :reporter]
+    end
+
+    it 'does not allow non-members to read issues' do
+      expect(permissions(non_member, issue)).not_to include(:read_issue, :update_issue, :admin_issue)
+      expect(permissions(non_member, issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+    end
+
+    it 'allows guests to read issues' do
+      expect(permissions(guest, issue)).to include(:read_issue)
+      expect(permissions(guest, issue)).not_to include(:update_issue, :admin_issue)
+
+      expect(permissions(guest, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(guest, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    it 'allows reporters to read, update, and admin issues' do
+      expect(permissions(reporter, issue)).to include(:read_issue, :update_issue, :admin_issue)
+      expect(permissions(reporter, issue_no_assignee)).to include(:read_issue, :update_issue, :admin_issue)
+    end
+
+    it 'allows issue authors to read and update their issues' do
+      expect(permissions(author, issue)).to include(:read_issue, :update_issue)
+      expect(permissions(author, issue)).not_to include(:admin_issue)
+
+      expect(permissions(author, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(author, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    it 'allows issue assignees to read and update their issues' do
+      expect(permissions(assignee, issue)).to include(:read_issue, :update_issue)
+      expect(permissions(assignee, issue)).not_to include(:admin_issue)
+
+      expect(permissions(assignee, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(assignee, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    context 'with confidential issues' do
+      let(:confidential_issue) { create(:issue, :confidential, project: project, assignee: assignee, author: author) }
+      let(:confidential_issue_no_assignee) { create(:issue, :confidential, project: project) }
+
+      it 'does not allow non-members to read confidential issues' do
+        expect(permissions(non_member, confidential_issue)).not_to include(:read_issue, :update_issue, :admin_issue)
+        expect(permissions(non_member, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'does not allow guests to read confidential issues' do
+        expect(permissions(guest, confidential_issue)).not_to include(:read_issue, :update_issue, :admin_issue)
+        expect(permissions(guest, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows reporters to read, update, and admin confidential issues' do
+        expect(permissions(reporter, confidential_issue)).to include(:read_issue, :update_issue, :admin_issue)
+        expect(permissions(reporter, confidential_issue_no_assignee)).to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows issue authors to read and update their confidential issues' do
+        expect(permissions(author, confidential_issue)).to include(:read_issue, :update_issue)
+        expect(permissions(author, confidential_issue)).not_to include(:admin_issue)
+
+        expect(permissions(author, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows issue assignees to read and update their confidential issues' do
+        expect(permissions(assignee, confidential_issue)).to include(:read_issue, :update_issue)
+        expect(permissions(assignee, confidential_issue)).not_to include(:admin_issue)
+
+        expect(permissions(assignee, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+    end
+  end
+
+  context 'a public project' do
+    let(:project) { create(:empty_project, :public) }
+    let(:issue) { create(:issue, project: project, assignee: assignee, author: author) }
+    let(:issue_no_assignee) { create(:issue, project: project) }
+
+    before do
+      project.team << [guest, :guest]
+      project.team << [reporter, :reporter]
+    end
+
+    it 'allows guests to read issues' do
+      expect(permissions(guest, issue)).to include(:read_issue)
+      expect(permissions(guest, issue)).not_to include(:update_issue, :admin_issue)
+
+      expect(permissions(guest, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(guest, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    it 'allows reporters to read, update, and admin issues' do
+      expect(permissions(reporter, issue)).to include(:read_issue, :update_issue, :admin_issue)
+      expect(permissions(reporter, issue_no_assignee)).to include(:read_issue, :update_issue, :admin_issue)
+    end
+
+    it 'allows issue authors to read and update their issues' do
+      expect(permissions(author, issue)).to include(:read_issue, :update_issue)
+      expect(permissions(author, issue)).not_to include(:admin_issue)
+
+      expect(permissions(author, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(author, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    it 'allows issue assignees to read and update their issues' do
+      expect(permissions(assignee, issue)).to include(:read_issue, :update_issue)
+      expect(permissions(assignee, issue)).not_to include(:admin_issue)
+
+      expect(permissions(assignee, issue_no_assignee)).to include(:read_issue)
+      expect(permissions(assignee, issue_no_assignee)).not_to include(:update_issue, :admin_issue)
+    end
+
+    context 'with confidential issues' do
+      let(:confidential_issue) { create(:issue, :confidential, project: project, assignee: assignee, author: author) }
+      let(:confidential_issue_no_assignee) { create(:issue, :confidential, project: project) }
+
+      it 'does not allow guests to read confidential issues' do
+        expect(permissions(guest, confidential_issue)).not_to include(:read_issue, :update_issue, :admin_issue)
+        expect(permissions(guest, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows reporters to read, update, and admin confidential issues' do
+        expect(permissions(reporter, confidential_issue)).to include(:read_issue, :update_issue, :admin_issue)
+        expect(permissions(reporter, confidential_issue_no_assignee)).to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows issue authors to read and update their confidential issues' do
+        expect(permissions(author, confidential_issue)).to include(:read_issue, :update_issue)
+        expect(permissions(author, confidential_issue)).not_to include(:admin_issue)
+
+        expect(permissions(author, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+
+      it 'allows issue assignees to read and update their confidential issues' do
+        expect(permissions(assignee, confidential_issue)).to include(:read_issue, :update_issue)
+        expect(permissions(assignee, confidential_issue)).not_to include(:admin_issue)
+
+        expect(permissions(assignee, confidential_issue_no_assignee)).not_to include(:read_issue, :update_issue, :admin_issue)
+      end
+    end
+  end
+end