chore: update test cases with comments

internals/daemon/daemon_test.go

@@ -1339,7 +1339,7 @@ services:
 	rsp.ServeHTTP(rec, req)
 	c.Check(rec.Result().StatusCode, Equals, 202)
 
-	// Wait for the change to be in doing state.
+	// Wait for the change to be in doing state so that the service is in starting state.
 	for i := 0; ; i++ {
 		if i >= 10 {
 			c.Fatalf("timed out waiting for change")
@@ -1354,12 +1354,11 @@ services:
 		time.Sleep(20 * time.Millisecond)
 	}
 
-	// Stop the daemon within the okayDelay,
-	// which should stop services in running state.
+	// Stop the daemon within the okayDelay, which should stop services in starting state.
 	err = d.Stop(nil)
 	c.Assert(err, IsNil)
 
-	// Ensure the "stop" change was created, along with its "stop" tasks.
+	// Ensure a "stop" change is created, along with its "stop" tasks.
 	d.state.Lock()
 	defer d.state.Unlock()
 	changes := d.state.Changes()

internals/overlord/servstate/manager_test.go

@@ -298,12 +298,13 @@ services:
 }
 
 func (s *S) TestStopServiceWithinOkayDelay(c *C) {
-	// A longer okayDelay is used so that the change for starting the services won't
+	// A longer okayDelay is used so that the change for starting the service won't
 	// quickly transition into the running state.
 	fakeOkayDelay := 5 * shortOkayDelay
 	servstate.FakeOkayWait(fakeOkayDelay)
 
 	s.newServiceManager(c)
+	// The service sleeps for fakeOkayDelay second then creates a side effect (a file at donePath).
 	layer := `
 services:
     %s:
@@ -337,7 +338,7 @@ services:
 	s.st.Unlock()
 
 	donePath := filepath.Join(s.dir, serviceName)
-	// DonePath not created means the service is terminated within the okayWait.
+	// If the service is stopped within okayDelay and is indeed terminated, donePath should not exist.
 	if _, err := os.Stat(donePath); err == nil {
 		c.Fatalf("service %s waiting for service output", serviceName)
 	}