#128 Raising an error in case mapped enum constants don't exist

processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java

@@ -26,7 +26,6 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-
 import javax.annotation.processing.Messager;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
@@ -756,6 +755,10 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
     }
 
     private EnumMappingMethod getEnumMappingMethod(SourceMethod method) {
+        if ( !reportErrorIfMappedEnumConstantsDontExist( method ) ) {
+            return null;
+        }
+
         List<EnumMapping> enumMappings = new ArrayList<EnumMapping>();
 
         List<String> sourceEnumConstants = method.getSourceParameters().iterator().next().getType().getEnumConstants();
@@ -786,12 +789,76 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
                     method.getExecutable()
                 );
             }
-
         }
 
         return new EnumMappingMethod( method, enumMappings );
     }
 
+    private boolean reportErrorIfMappedEnumConstantsDontExist(SourceMethod method) {
+        // only report errors if this method itself is configured
+        if ( method.isConfiguredByReverseMappingMethod() ) {
+            return true;
+        }
+
+        List<String> sourceEnumConstants = method.getSourceParameters().iterator().next().getType().getEnumConstants();
+        List<String> targetEnumConstants = method.getReturnType().getEnumConstants();
+
+        boolean foundIncorrectMapping = false;
+
+        for ( List<Mapping> mappedConstants : method.getMappings().values() ) {
+            for ( Mapping mappedConstant : mappedConstants ) {
+                if ( mappedConstant.getSourceName() == null ) {
+                    messager.printMessage(
+                        Kind.ERROR,
+                        "A source constant must be specified for mappings of an enum mapping method.",
+                        method.getExecutable(),
+                        mappedConstant.getMirror()
+                    );
+                    foundIncorrectMapping = true;
+                }
+                else if ( !sourceEnumConstants.contains( mappedConstant.getSourceName() ) ) {
+                    messager.printMessage(
+                        Kind.ERROR,
+                        String.format(
+                            "Constant %s doesn't exist in enum type %s.",
+                            mappedConstant.getSourceName(),
+                            method.getSourceParameters().iterator().next().getType()
+                        ),
+                        method.getExecutable(),
+                        mappedConstant.getMirror(),
+                        mappedConstant.getSourceAnnotationValue()
+                    );
+                    foundIncorrectMapping = true;
+                }
+                if ( mappedConstant.getTargetName() == null ) {
+                    messager.printMessage(
+                        Kind.ERROR,
+                        "A target constant must be specified for mappings of an enum mapping method.",
+                        method.getExecutable(),
+                        mappedConstant.getMirror()
+                    );
+                    foundIncorrectMapping = true;
+                }
+                else if ( !targetEnumConstants.contains( mappedConstant.getTargetName() ) ) {
+                    messager.printMessage(
+                        Kind.ERROR,
+                        String.format(
+                            "Constant %s doesn't exist in enum type %s.",
+                            mappedConstant.getTargetName(),
+                            method.getReturnType()
+                        ),
+                        method.getExecutable(),
+                        mappedConstant.getMirror(),
+                        mappedConstant.getTargetAnnotationValue()
+                    );
+                    foundIncorrectMapping = true;
+                }
+            }
+        }
+
+        return !foundIncorrectMapping;
+    }
+
     private TypeConversion getConversion(Type sourceType, Type targetType, String dateFormat, String sourceReference) {
         ConversionProvider conversionProvider = conversions.getConversion( sourceType, targetType );
 

processor/src/test/java/org/mapstruct/ap/test/enums/EnumMappingTest.java

@@ -83,6 +83,24 @@ public class EnumMappingTest extends MapperTestBase {
         }
     )
     public void shouldRaiseErrorIfSameSourceEnumConstantIsMappedTwice() {
+    }
 
+    @Test
+    @WithClasses(ErroneousOrderMapperUsingUnknownEnumConstants.class)
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousOrderMapperUsingUnknownEnumConstants.class,
+                kind = Kind.ERROR,
+                line = 35,
+                messageRegExp = "Constant FOO doesn't exist in enum type org.mapstruct.ap.test.enums.OrderType\\."),
+            @Diagnostic(type = ErroneousOrderMapperUsingUnknownEnumConstants.class,
+                kind = Kind.ERROR,
+                line = 36,
+                messageRegExp = "Constant BAR doesn't exist in enum type org.mapstruct.ap.test.enums." +
+                    "ExternalOrderType\\.")
+        }
+    )
+    public void shouldRaiseErrorIfUnknownEnumConstantsAreSpecifiedInMapping() {
     }
 }

processor/src/test/java/org/mapstruct/ap/test/enums/ErroneousOrderMapperUsingUnknownEnumConstants.java

@@ -0,0 +1,41 @@
+/**
+ *  Copyright 2012-2014 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.enums;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.Mappings;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Gunnar Morling
+ */
+@Mapper
+public interface ErroneousOrderMapperUsingUnknownEnumConstants {
+
+    ErroneousOrderMapperUsingUnknownEnumConstants INSTANCE = Mappers.getMapper(
+        ErroneousOrderMapperUsingUnknownEnumConstants.class
+    );
+
+    @Mappings({
+        @Mapping(source = "FOO", target = "SPECIAL"),
+        @Mapping(source = "EXTRA", target = "BAR"),
+    })
+    ExternalOrderType orderTypeToExternalOrderType(OrderType orderType);
+}