Add comment explaining if and add a test

Author: Jlalond

lldb/include/lldb/Core/DebuggerEvents.h

@@ -44,6 +44,7 @@ class ProgressEventData : public EventData {
   uint64_t GetCompleted() const { return m_completed; }
   uint64_t GetTotal() const { return m_total; }
   std::string GetMessage() const {
+    // Only put the title in the message of the progress create event.
     if (m_completed == 0) {
       std::string message = m_title;
       if (!m_details.empty()) {

lldb/test/API/tools/lldb-dap/progress/TestDAP_Progress.py

@@ -41,8 +41,13 @@ def test_output(self):
         for event in self.dap_server.progress_events:
             event_type = event["event"]
             if "progressStart" in event_type:
+                title = event["body"]["title"]
+                self.assertIn("Progress tester", title)
                 start_found = True
             if "progressUpdate" in event_type:
+                message = event["body"]["message"]
+                print(f"Progress update: {message}")
+                self.assertNotIn("Progres tester", message)
                 update_found = True
 
         self.assertTrue(start_found)