Add TypeAdapterFactory for validating Gobpie configuration

src/main/java/api/json/GobPieConfValidatorAdapterFactory.java

@@ -0,0 +1,79 @@
+package api.json;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.internal.bind.ReflectiveTypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+
+import java.lang.reflect.Field;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * A class for handling unexpected fields in GobPie configuration.
+ * Code adapted from <a href="https://github.com/google/gson/issues/188">a Gson library issue</a>.
+ *
+ * @since 0.0.4
+ */
+
+public class GobPieConfValidatorAdapterFactory implements TypeAdapterFactory {
+
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+        // If the type adapter is a reflective type adapter, we want to modify the implementation using reflection.
+        // The trick is to replace the Map object used to look up the property name.
+        // Instead of returning null if the property is not found,
+        // we throw a Json exception to terminate the deserialization.
+        TypeAdapter<T> delegateAdapter = gson.getDelegateAdapter(this, type);
+
+        // Check if the type adapter is a reflective, cause this solution only work for reflection.
+        if (delegateAdapter instanceof ReflectiveTypeAdapterFactory.Adapter) {
+
+            try {
+                // Get reference to the existing boundFields.
+                Field f = findBoundField(delegateAdapter.getClass());
+                f.setAccessible(true);
+                // Finally, push our custom map back using reflection.
+                f.set(delegateAdapter, getBoundFields(f, delegateAdapter));
+            } catch (Exception e) {
+                // Should never happen if the implementation doesn't change.
+                throw new IllegalStateException(e);
+            }
+
+        }
+        return delegateAdapter;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static <T> Object getBoundFields(Field f, TypeAdapter<T> delegate) throws IllegalAccessException {
+        Object boundFields = f.get(delegate);
+
+        // Then replace it with our implementation throwing exception if the value is null.
+        boundFields = new LinkedHashMap<>((Map<Object, Object>) boundFields) {
+
+            @Override
+            public Object get(Object key) {
+                Object value = super.get(key);
+                if (value == null) {
+                    throw new JsonParseException(String.valueOf(key));
+                }
+                return value;
+            }
+
+        };
+        return boundFields;
+    }
+
+    private static Field findBoundField(Class<?> startingClass) throws NoSuchFieldException {
+        for (Class<?> c = startingClass; c != null; c = c.getSuperclass()) {
+            try {
+                return c.getDeclaredField("boundFields");
+            } catch (NoSuchFieldException e) {
+                // OK: continue with superclasses
+            }
+        }
+        throw new NoSuchFieldException("boundFields starting from " + (startingClass != null ? startingClass.getName() : null));
+    }
+}

src/main/java/gobpie/GobPieConfReader.java

@@ -1,5 +1,6 @@
 package gobpie;
 
+import api.json.GobPieConfValidatorAdapterFactory;
 import com.google.gson.*;
 import magpiebridge.core.MagpieServer;
 import org.apache.commons.lang3.exception.ExceptionUtils;
@@ -93,21 +94,25 @@ public GobPieConfiguration readGobPieConfiguration() {
     public GobPieConfiguration parseGobPieConf() {
         try {
             log.debug("Reading GobPie configuration from json");
-            Gson gson = new GsonBuilder().create();
+            Gson gson = new GsonBuilder()
+                    .registerTypeAdapterFactory(new GobPieConfValidatorAdapterFactory())
+                    .create();
             // Read json object
             JsonObject jsonObject = JsonParser.parseReader(new FileReader(gobPieConfFileName)).getAsJsonObject();
             // Convert json object to GobPieConfiguration object
             log.debug("GobPie configuration read from json");
             return gson.fromJson(jsonObject, GobPieConfiguration.class);
-        } catch (FileNotFoundException e) {
-            throw new GobPieException("Could not locate GobPie configuration file.", e, GobPieExceptionType.GOBPIE_CONF_EXCEPTION);
         } catch (JsonSyntaxException e) {
             throw new GobPieException("GobPie configuration file syntax is wrong.", e, GobPieExceptionType.GOBPIE_CONF_EXCEPTION);
+        } catch (JsonParseException e) {
+            throw new GobPieException("There was an unknown option \"" + e.getMessage() + "\" in the GobPie configuration. Please check for any typos.", e, GobPieExceptionType.GOBPIE_CONF_EXCEPTION);
+        } catch (FileNotFoundException e) {
+            throw new GobPieException("Could not locate GobPie configuration file.", e, GobPieExceptionType.GOBPIE_CONF_EXCEPTION);
         }
     }
 
 
-/**
+    /**
      * Method for forwarding Error messages to MagpieServer.
      *
      * @param popUpMessage    The message shown on the pop-up message.

src/test/java/GobPieConfTest.java

@@ -137,22 +137,8 @@ void testReadGobPieConfigurationWithWrongJSONSyntax() {
     @Test
     void testReadGobPieConfigurationWithExtraField() {
         GobPieConfReader gobPieConfReader = preFileSetup(5);
-        GobPieConfiguration expectedGobPieConfiguration =
-                new GobPieConfiguration.Builder()
-                        .setGoblintConf("goblint.json")
-                        .setGoblintExecutable("/home/user/goblint/analyzer/goblint")
-                        .setPreAnalyzeCommand(new String[]{"cmake", "-DCMAKE_EXPORT_COMPILE_COMMANDS=ON", "-B", "build"})
-                        .setAbstractDebugging(false)
-                        .setShowCfg(false)
-                        .setIncrementalAnalysis(true)
-                        .setExplodeGroupWarnings(false)
-                        .createGobPieConfiguration();
-
-        GobPieConfiguration actualGobPieConfiguration = gobPieConfReader.readGobPieConfiguration();
-        assertTrue(systemOut.getLines().anyMatch(line -> line.contains("Reading GobPie configuration from json")));
-        verify(magpieServer).forwardMessageToClient(new MessageParams(MessageType.Error, "There was an unknown option in the GobPie configuration. Please check for any typos."));
-        //assertTrue(systemOut.getLines().anyMatch(line -> line.contains("GobPie configuration read from json")));
-        assertEquals(expectedGobPieConfiguration, actualGobPieConfiguration);
+        GobPieException thrown = assertThrows(GobPieException.class, gobPieConfReader::readGobPieConfiguration);
+        assertEquals("There was an unknown option \"extraField\" in the GobPie configuration. Please check for any typos.", thrown.getMessage());
     }
 
     /**