Fix incorrect file name regex logic

directjngine/src/main/java/com/softwarementors/extjs/djn/jscodegen/CodeFileGenerator.java

@@ -166,9 +166,13 @@ private static boolean fileContentEquals(File file, String code) throws IOExcept
     }
     return false;
   }
-  
+
   private static String getDebugFileName( String file ) {
-    String result = file.replace( ".js", "-debug.js");
-    return result;
+    int extensionIndex = file.lastIndexOf( ".js" );
+
+    if ( extensionIndex != -1 && file.endsWith(".js") ) {
+      return file.substring(0, extensionIndex) + "-debug.js";
+    }
+    return file;
   }
 }

directjngine/src/test/java/com/softwarementors/extjs/djn/jscodegen/CodeFileGeneratorTest.java

@@ -0,0 +1,34 @@
+package com.softwarementors.extjs.djn.jscodegen;
+
+import org.testng.annotations.Test;
+
+import java.lang.reflect.Method;
+
+import static org.testng.Assert.*;
+
+public class CodeFileGeneratorTest {
+
+    private String getDebugFileName(String file) {
+        try {
+            Method method = CodeFileGenerator.class.getDeclaredMethod("getDebugFileName", String.class);
+            method.setAccessible(true);
+            Object result = method.invoke(null, file);
+            return (String) result;
+        } catch (Exception e) {
+            e.printStackTrace();
+            return "";
+        }
+    }
+
+    @Test
+    public void getDebugFileNameTest() {
+        assertEquals(
+                "john.jspiner",
+                getDebugFileName("john.jspiner")
+        );
+        assertEquals(
+                "app-debug.js",
+                getDebugFileName("app.js")
+        );
+    }
+}