Refs 11857. Added comments on test.

Signed-off-by: Miguel Company <MiguelCompany@eprosima.com>

test/blackbox/common/DDSBlackboxTestsDiscovery.cpp

@@ -21,12 +21,18 @@
 // Regression test for redmine issue 11857
 TEST(DDSDiscovery, IgnoreParticipantFlags)
 {
+    // This participant is created with:
+    // - ignoreParticipantFlags = FILTER_SAME_PROCESS (will avoid discovery of p2)
+    // - metatrafficUnicastLocatorList = 127.0.0.1:7399, 127.0.0.1:7398 (to ensure two listening threads are created)
     PubSubReader<HelloWorldType> p1(TEST_TOPIC_NAME);
     p1.set_xml_filename("discovery_participant_flags.xml");
     p1.set_participant_profile("participant_1");
     p1.init();
     EXPECT_TRUE(p1.isInitialized());
 
+    // This participant is created with initialPeersList = 127.0.0.1:7399
+    // When the announcements of this participant arrive to p1, they will be ignored, and thus p1 will not
+    // announce itself back to p2.
     PubSubReader<HelloWorldType> p2(TEST_TOPIC_NAME);
     p2.set_xml_filename("discovery_participant_flags.xml");
     p2.set_participant_profile("participant_2");
@@ -35,6 +41,11 @@ TEST(DDSDiscovery, IgnoreParticipantFlags)
     EXPECT_FALSE(p2.wait_participant_discovery(1, std::chrono::seconds(1)));
     EXPECT_FALSE(p1.wait_participant_discovery(1, std::chrono::seconds(1)));
 
+    // This participant is created with:
+    // - initialPeersList = 127.0.0.1:7398
+    // - a custom guid prefix
+    // The announcements of this participant will arrive to p1 on a different listening thread.
+    // Due to the custom prefix, they should not be ignored, and mutual discovery should happen
     PubSubReader<HelloWorldType> p3(TEST_TOPIC_NAME);
     p3.set_xml_filename("discovery_participant_flags.xml");
     p3.set_participant_profile("participant_3");