Add specs for billing_enabled change counter

spec/workers/check_gcp_project_billing_worker_spec.rb

@@ -6,6 +6,11 @@ describe CheckGcpProjectBillingWorker do
 
     subject { described_class.new.perform('token_key') }
 
+    before do
+      allow_any_instance_of(described_class).to receive(:check_previous_state)
+      allow_any_instance_of(described_class).to receive(:update_billing_change_counter)
+    end
+
     context 'when there is a token in redis' do
       before do
         allow(described_class).to receive(:get_session_token).and_return(token)
@@ -58,4 +63,65 @@ describe CheckGcpProjectBillingWorker do
       end
     end
   end
+
+  describe 'billing change counter' do
+    subject { described_class.new.perform('token_key') }
+
+    before do
+      allow(described_class).to receive(:get_session_token).and_return('bogustoken')
+      allow_any_instance_of(described_class).to receive(:try_obtain_lease_for).and_return('randomuuid')
+      Gitlab::Redis::SharedState.with do |redis|
+        allow(redis).to receive(:set)
+      end
+    end
+
+    context 'when previous state was false' do
+      before do
+        expect_any_instance_of(described_class).to receive(:check_previous_state).and_return('false')
+      end
+
+      context 'when the current state is false' do
+        before do
+          expect(CheckGcpProjectBillingService).to receive_message_chain(:new, :execute).and_return([])
+        end
+
+        it 'does not increment the billing change counter' do
+          Gitlab::Redis::SharedState.with do |redis|
+            expect(redis).not_to receive(:incr)
+          end
+
+          subject
+        end
+      end
+
+      context 'when the current state is true' do
+        before do
+          expect(CheckGcpProjectBillingService).to receive_message_chain(:new, :execute).and_return([double])
+        end
+
+        it 'increments the billing change counter' do
+          Gitlab::Redis::SharedState.with do |redis|
+            expect(redis).to receive(:incr)
+          end
+
+          subject
+        end
+      end
+    end
+
+    context 'when previous state was true' do
+      before do
+        expect_any_instance_of(described_class).to receive(:check_previous_state).and_return('true')
+        expect(CheckGcpProjectBillingService).to receive_message_chain(:new, :execute).and_return([double])
+      end
+
+      it 'does not increment the billing change counter' do
+        Gitlab::Redis::SharedState.with do |redis|
+          expect(redis).not_to receive(:incr)
+        end
+
+        subject
+      end
+    end
+  end
 end