Use current active user count to determine whether license is valid.

Previously, the EE license check used the historical maximum to determine
whether an admin has enough seats for the license. Let's say a customer has a
5-seat license, and sometime during the year he had 20 users. If he/she trims back
to 4 users, the 5-seat license won't work anymore. Right now the workaround is
to issue a license for 20 users.

Closes #550

CHANGELOG-EE

 Please view this file on the master branch, on stable branches it's out of date.
 v 8.8.0 (unreleased)
+  - Use current active user count to determine whether license is valid
   - [Elastic] Database indexer prints its status
   - [Elastic][Fix] Database indexer skips projects with invalid HEAD reference
   - [Elastic] More efficient snippets search

app/models/license.rb

@@ -108,7 +108,7 @@ def active_user_count
     restricted_user_count = self.restrictions[:active_user_count]
     date_range = (self.starts_at - 1.year)..self.starts_at
-    active_user_count = HistoricalData.during(date_range).maximum(:active_user_count) || 0
+    active_user_count = User.active.count
     return unless active_user_count
@@ -117,7 +117,7 @@ def active_user_count
     overage = active_user_count - restricted_user_count
     message = ""
-    message << "During the year before this license started, this GitLab installation had "
+    message << "This GitLab installation currently has "
     message << "#{number_with_delimiter active_user_count} active #{"user".pluralize(active_user_count)}, "
     message << "exceeding this license's limit of #{number_with_delimiter restricted_user_count} by "
     message << "#{number_with_delimiter overage} #{"user".pluralize(overage)}. "

spec/models/license_spec.rb

@@ -23,10 +23,13 @@
       end
     end
-    describe "Historical active user count" do
+    describe "Active user count" do
       let(:active_user_count) { User.active.count + 10 }
       let(:date)              { License.current.starts_at }
-      let!(:historical_data)  { HistoricalData.create!(date: date, active_user_count: active_user_count) }
+
+      before do
+        allow(User).to receive(:active).and_return(Array.new(active_user_count))
+      end
       context "when there is no active user count restriction" do
         it "is valid" do
@@ -39,34 +42,8 @@
           gl_license.restrictions = { active_user_count: active_user_count - 1 }
         end
-        context "when the license started" do
-          it "is invalid" do
-            expect(license).not_to be_valid
-          end
-        end
-
-        context "after the license started" do
-          let(:date) { Date.today }
-
-          it "is valid" do
-            expect(license).to be_valid
-          end
-        end
-
-        context "in the year before the license started" do
-          let(:date) { License.current.starts_at - 6.months }
-
-          it "is invalid" do
-            expect(license).not_to be_valid
-          end
-        end
-
-        context "earlier than a year before the license started" do
-          let(:date) { License.current.starts_at - 2.years }
-
-          it "is valid" do
-            expect(license).to be_valid
-          end
+        it "is invalid" do
+          expect(license).not_to be_valid
         end
       end