Fix InvalidXmlCharacterFilter failing to parse CDATA

src/main/java/com/apptasticsoftware/rssreader/filter/InvalidXmlCharacterFilter.java

@@ -212,11 +212,20 @@ private void refillBuffer() throws IOException {
                             cdataBuffer.setLength(0);
                         }
                     } else {
+                        // Character doesn't match the next position in "]]>"
+                        // First, write any previously buffered partial "]]>" match
                         if (cdataEndMatchPos > 0) {
-                            cdataBuffer.append(ch);
+                            writeStringToBuffer(cdataBuffer.toString());
+                            cdataBuffer.setLength(0);
                             cdataEndMatchPos = 0;
+                        }
+                        // Now check if current character could start a new "]]>" match
+                        if (ch == CDATA_END.charAt(0)) {
+                            // Start matching "]]>"
+                            cdataEndMatchPos = 1;
+                            cdataBuffer.append(ch);
                         } else {
-                            // Inside CDATA, write character as-is (but still validate XML char)
+                            // Just a regular character in CDATA
                             writeStringToBuffer(String.valueOf(ch));
                         }
                     }

src/test/java/com/apptasticsoftware/integrationtest/FeedFilterTest.java

@@ -65,6 +65,18 @@ void testInvalidXmlEscapeStringWithinCdata() {
                 item.getDescription().orElse(""));
     }
 
+    @Test
+    void testCdataEndingWithTripleRightSquareBrackets() {
+        var items = new RssReader()
+                .addFeedFilter(new InvalidXmlCharacterFilter())
+                .read(fromFile("rss-cdata-ending-triple-right-square-brackets.xml")).collect(Collectors.toList());
+
+        assertEquals(20, items.size());
+        var item = items.get(0);
+
+        assertEquals("Sorti le 21 octobre dernier, Painkiller, le FPS action-coop « revisitant » le cultissime et unique Painkiller des années 2000 cher à nos cœurs, n’a pas connu le succès escompté et sa petite fanbase de joueurs commençait à s’inquiéter de ne pas avoir de nouvelles. Fort heureusement, la semaine dernière, le studio Anshar a publié […]", item.getDescription().orElse(""));
+    }
+
     private InputStream fromFile(String fileName) {
         return getClass().getClassLoader().getResourceAsStream(fileName);
     }