Add config option to fail on unknown enum values

src/main/java/com/hubspot/jackson/datatype/protobuf/ProtobufJacksonConfig.java

@@ -5,10 +5,13 @@
 public class ProtobufJacksonConfig {
   private final ExtensionRegistryWrapper extensionRegistry;
   private final boolean acceptLiteralFieldnames;
+  private final UnknownEnumSerializationStrategy unknownEnumSerializationStrategy;
 
-  private ProtobufJacksonConfig(ExtensionRegistryWrapper extensionRegistry, boolean acceptLiteralFieldnames) {
+  private ProtobufJacksonConfig(ExtensionRegistryWrapper extensionRegistry, boolean acceptLiteralFieldnames,
+      UnknownEnumSerializationStrategy unknownEnumSerializationStrategy) {
     this.extensionRegistry = extensionRegistry;
     this.acceptLiteralFieldnames = acceptLiteralFieldnames;
+    this.unknownEnumSerializationStrategy = unknownEnumSerializationStrategy;
   }
 
   public static Builder builder() {
@@ -23,9 +26,14 @@ public boolean acceptLiteralFieldnames() {
     return acceptLiteralFieldnames;
   }
 
+  public UnknownEnumSerializationStrategy unknownEnumSerializationStrategy() {
+    return unknownEnumSerializationStrategy;
+  }
+
   public static class Builder {
     private ExtensionRegistryWrapper extensionRegistry = ExtensionRegistryWrapper.empty();
     private boolean acceptLiteralFieldnames = false;
+    private UnknownEnumSerializationStrategy unknownEnumSerializationStrategy = UnknownEnumSerializationStrategy.SERIALIZE;
 
     private Builder() {}
 
@@ -43,8 +51,13 @@ public Builder acceptLiteralFieldnames(boolean acceptLiteralFieldnames) {
       return this;
     }
 
+    public Builder unknownEnumSerializationStrategy(UnknownEnumSerializationStrategy unknownEnumSerializationStrategy) {
+      this.unknownEnumSerializationStrategy = unknownEnumSerializationStrategy;
+      return this;
+    }
+
     public ProtobufJacksonConfig build() {
-      return new ProtobufJacksonConfig(extensionRegistry, acceptLiteralFieldnames);
+      return new ProtobufJacksonConfig(extensionRegistry, acceptLiteralFieldnames, unknownEnumSerializationStrategy);
     }
   }
 }

src/main/java/com/hubspot/jackson/datatype/protobuf/ProtobufModule.java

@@ -82,22 +82,22 @@ public Version version() {
   public void setupModule(SetupContext context) {
     SimpleSerializers serializers = new SimpleSerializers();
     serializers.addSerializer(new MessageSerializer(config));
-    serializers.addSerializer(new DurationSerializer());
-    serializers.addSerializer(new FieldMaskSerializer());
-    serializers.addSerializer(new ListValueSerializer());
+    serializers.addSerializer(new DurationSerializer(config));
+    serializers.addSerializer(new FieldMaskSerializer(config));
+    serializers.addSerializer(new ListValueSerializer(config));
     serializers.addSerializer(new NullValueSerializer());
-    serializers.addSerializer(new StructSerializer());
-    serializers.addSerializer(new TimestampSerializer());
-    serializers.addSerializer(new ValueSerializer());
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(DoubleValue.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(FloatValue.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(Int64Value.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(UInt64Value.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(Int32Value.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(UInt32Value.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(BoolValue.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(StringValue.class));
-    serializers.addSerializer(new WrappedPrimitiveSerializer<>(BytesValue.class));
+    serializers.addSerializer(new StructSerializer(config));
+    serializers.addSerializer(new TimestampSerializer(config));
+    serializers.addSerializer(new ValueSerializer(config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(DoubleValue.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(FloatValue.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(Int64Value.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(UInt64Value.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(Int32Value.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(UInt32Value.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(BoolValue.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(StringValue.class, config));
+    serializers.addSerializer(new WrappedPrimitiveSerializer<>(BytesValue.class, config));
 
     context.addSerializers(serializers);
 

src/main/java/com/hubspot/jackson/datatype/protobuf/ProtobufSerializer.java

@@ -25,9 +25,11 @@ public abstract class ProtobufSerializer<T extends MessageOrBuilder> extends Std
   private static final String NULL_VALUE_FULL_NAME = NullValue.getDescriptor().getFullName();
 
   private final Map<Class<?>, JsonSerializer<Object>> serializerCache;
+  private final ProtobufJacksonConfig config;
 
-  public ProtobufSerializer(Class<T> protobufType) {
+  public ProtobufSerializer(Class<T> protobufType, ProtobufJacksonConfig config) {
     super(protobufType);
+    this.config = config;
 
     this.serializerCache = new ConcurrentHashMap<>();
   }
@@ -84,10 +86,16 @@ protected void writeValue(
         // special-case NullValue
         if (NULL_VALUE_FULL_NAME.equals(enumDescriptor.getType().getFullName())) {
           generator.writeNull();
-        } else if (writeEnumsUsingIndex(serializerProvider)) {
-          generator.writeNumber(enumDescriptor.getNumber());
         } else {
-          generator.writeString(enumDescriptor.getName());
+          if (isUnknownEnumValue(enumDescriptor)) {
+            enumDescriptor = config.unknownEnumSerializationStrategy().handleUnknownEnumValue(enumDescriptor);
+          }
+
+          if (writeEnumsUsingIndex(serializerProvider)) {
+            generator.writeNumber(enumDescriptor.getNumber());
+          } else {
+            generator.writeString(enumDescriptor.getName());
+          }
         }
         break;
       case BYTE_STRING:
@@ -113,6 +121,10 @@ private static boolean writeEnumsUsingIndex(SerializerProvider config) {
     return config.isEnabled(SerializationFeature.WRITE_ENUMS_USING_INDEX);
   }
 
+  private static boolean isUnknownEnumValue(EnumValueDescriptor descriptor) {
+    return descriptor.getType().findValueByNumber(descriptor.getNumber()) == null;
+  }
+
   private static IOException unrecognizedType(FieldDescriptor field, JsonGenerator generator) throws IOException {
     String error = format("Unrecognized java type '%s' for field %s", field.getJavaType(), field.getFullName());
     throw new JsonGenerationException(error, generator);

src/main/java/com/hubspot/jackson/datatype/protobuf/UnknownEnumSerializationStrategy.java

@@ -0,0 +1,17 @@
+package com.hubspot.jackson.datatype.protobuf;
+
+import com.google.protobuf.Descriptors.EnumValueDescriptor;
+
+@FunctionalInterface
+public interface UnknownEnumSerializationStrategy {
+
+  EnumValueDescriptor handleUnknownEnumValue(EnumValueDescriptor descriptor);
+
+  UnknownEnumSerializationStrategy SERIALIZE = descriptor -> descriptor;
+
+  UnknownEnumSerializationStrategy FAIL =
+      descriptor -> {
+        throw new IllegalArgumentException(
+            "Unable to serialize an unknown enum value " + descriptor.getFullName());
+      };
+}

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/DurationSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -10,8 +11,8 @@
 
 public class DurationSerializer extends ProtobufSerializer<Duration> {
 
-  public DurationSerializer() {
-    super(Duration.class);
+  public DurationSerializer(ProtobufJacksonConfig config) {
+    super(Duration.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/FieldMaskSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -10,8 +11,8 @@
 
 public class FieldMaskSerializer extends ProtobufSerializer<FieldMask> {
 
-  public FieldMaskSerializer() {
-    super(FieldMask.class);
+  public FieldMaskSerializer(ProtobufJacksonConfig config) {
+    super(FieldMask.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/ListValueSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -12,8 +13,8 @@
 public class ListValueSerializer extends ProtobufSerializer<ListValue> {
   private static final FieldDescriptor VALUES_FIELD = ListValue.getDescriptor().findFieldByName("values");
 
-  public ListValueSerializer() {
-    super(ListValue.class);
+  public ListValueSerializer(ProtobufJacksonConfig config) {
+    super(ListValue.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/MessageSerializer.java

@@ -36,7 +36,7 @@ public MessageSerializer(ExtensionRegistryWrapper extensionRegistry) {
   }
 
   public MessageSerializer(ProtobufJacksonConfig config) {
-    super(MessageOrBuilder.class);
+    super(MessageOrBuilder.class, config);
 
     this.config = config;
   }

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/StructSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -11,8 +12,8 @@
 public class StructSerializer extends ProtobufSerializer<Struct> {
   private static final FieldDescriptor FIELDS_FIELD = Struct.getDescriptor().findFieldByName("fields");
 
-  public StructSerializer() {
-    super(Struct.class);
+  public StructSerializer(ProtobufJacksonConfig config) {
+    super(Struct.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/TimestampSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -10,8 +11,8 @@
 
 public class TimestampSerializer extends ProtobufSerializer<Timestamp> {
 
-  public TimestampSerializer() {
-    super(Timestamp.class);
+  public TimestampSerializer(ProtobufJacksonConfig config) {
+    super(Timestamp.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/ValueSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -12,8 +13,8 @@
 
 public class ValueSerializer extends ProtobufSerializer<Value> {
 
-  public ValueSerializer() {
-    super(Value.class);
+  public ValueSerializer(ProtobufJacksonConfig config) {
+    super(Value.class, config);
   }
 
   @Override

src/main/java/com/hubspot/jackson/datatype/protobuf/builtin/serializers/WrappedPrimitiveSerializer.java

@@ -1,5 +1,6 @@
 package com.hubspot.jackson.datatype.protobuf.builtin.serializers;
 
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
 import java.io.IOException;
 
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -10,8 +11,8 @@
 
 public class WrappedPrimitiveSerializer<T extends MessageOrBuilder> extends ProtobufSerializer<T> {
 
-  public WrappedPrimitiveSerializer(Class<T> wrapperType) {
-    super(wrapperType);
+  public WrappedPrimitiveSerializer(Class<T> wrapperType, ProtobufJacksonConfig config) {
+    super(wrapperType, config);
   }
 
   @Override

src/test/java/com/hubspot/jackson/datatype/protobuf/proto3/EnumTest.java

@@ -0,0 +1,30 @@
+package com.hubspot.jackson.datatype.protobuf.proto3;
+
+import static com.hubspot.jackson.datatype.protobuf.UnknownEnumSerializationStrategy.FAIL;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.hubspot.jackson.datatype.protobuf.ProtobufJacksonConfig;
+import com.hubspot.jackson.datatype.protobuf.ProtobufModule;
+import com.hubspot.jackson.datatype.protobuf.util.TestProtobuf3.NestedProto3;
+import org.junit.Test;
+
+public class EnumTest {
+
+  @Test
+  public void itFailsToSerializeAnUnknownEnum() {
+    ProtobufJacksonConfig config = ProtobufJacksonConfig.builder()
+        .unknownEnumSerializationStrategy(FAIL)
+        .build();
+
+    ObjectMapper mapper = new ObjectMapper().registerModules(new ProtobufModule(config));
+
+    NestedProto3 message = NestedProto3.newBuilder()
+        .setEnumValue(42)
+        .build();
+
+    assertThatThrownBy(() -> mapper.writeValueAsString(message))
+        .hasMessageContaining("Unable to serialize an unknown enum value")
+        .hasRootCauseInstanceOf(IllegalArgumentException.class);
+  }
+}