Merge branch 'feature/precalculate-authorized-projects' into 'master'

Precalculate authorized projects in database

## What does this MR do?
It caches user's authorized projects in database instead of using multiple unions, which should simplify and speed-up things since this operation (getting authorized projects) is used a lot.

## Are there points in the code the reviewer needs to double check?
Did we miss a scenario where we need to refresh the list of projects?

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
#23150 

See merge request !6839

1 files changed, 22 insertions, 0 deletions

diff --git a/spec/workers/authorized_projects_worker_spec.rb b/spec/workers/authorized_projects_worker_spec.rb
new file mode 100644
index 00000000000..18a1aab766c
--- /dev/null
+++ b/spec/workers/authorized_projects_worker_spec.rb
@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe AuthorizedProjectsWorker do
+  describe '#perform' do
+    it "refreshes user's authorized projects" do
+      user = create(:user)
+
+      expect(User).to receive(:find_by).with(id: user.id).and_return(user)
+      expect(user).to receive(:refresh_authorized_projects)
+
+      described_class.new.perform(user.id)
+    end
+
+    context "when user is not found" do
+      it "does nothing" do
+        expect_any_instance_of(User).not_to receive(:refresh_authorized_projects)
+
+        described_class.new.perform(999_999)
+      end
+    end
+  end
+end