Alter task spec to better test behavior

spec/tasks/gitlab/db_rake_spec.rb

@@ -100,26 +100,39 @@ describe 'gitlab:db namespace rake task' do
 
   describe 'clean_structure_sql' do
     let_it_be(:clean_rake_task) { 'gitlab:db:clean_structure_sql' }
+    let_it_be(:test_task_name) { 'gitlab:db:_test_multiple_structure_cleans' }
     let_it_be(:structure_file) { 'db/structure.sql' }
     let_it_be(:input) { 'this is structure data' }
     let(:output) { StringIO.new }
 
-    it 'reenables the task after running' do
+    before do
       allow(File).to receive(:read).with(structure_file).and_return(input)
       allow(File).to receive(:open).with(structure_file, any_args).and_yield(output)
-      expect_any_instance_of(Gitlab::Database::SchemaCleaner).to receive(:clean).with(output)
+    end
+
+    after do
+      Rake::Task[test_task_name].clear if Rake::Task.task_defined?(test_task_name)
+    end
 
-      run_rake_task(clean_rake_task) do |rake_task|
-        expect(rake_task).to receive(:reenable)
+    it 'can be executed multiple times within another rake task' do
+      Rake::Task.define_task(test_task_name => :environment) do
+        expect_next_instance_of(Gitlab::Database::SchemaCleaner) do |cleaner|
+          expect(cleaner).to receive(:clean).with(output)
+        end
+        Rake::Task[clean_rake_task].invoke
+
+        expect_next_instance_of(Gitlab::Database::SchemaCleaner) do |cleaner|
+          expect(cleaner).to receive(:clean).with(output)
+        end
+        Rake::Task[clean_rake_task].invoke
       end
+
+      run_rake_task(test_task_name)
     end
   end
 
   def run_rake_task(task_name)
-    rake_task = Rake::Task[task_name]
-    rake_task.reenable
-
-    yield rake_task if block_given?
+    Rake::Task[task_name].reenable
     Rake.application.invoke_task task_name
   end
 end