#1387 Improve error message when unknown source parameter is used in Mapping

processor/src/main/java/org/mapstruct/ap/internal/model/source/SourceReference.java

@@ -32,6 +32,7 @@ import javax.lang.model.type.DeclaredType;
 import org.mapstruct.ap.internal.model.common.Parameter;
 import org.mapstruct.ap.internal.model.common.Type;
 import org.mapstruct.ap.internal.model.common.TypeFactory;
+import org.mapstruct.ap.internal.util.Extractor;
 import org.mapstruct.ap.internal.util.FormattingMessager;
 import org.mapstruct.ap.internal.util.Message;
 import org.mapstruct.ap.internal.util.Strings;
@@ -132,7 +133,20 @@ public class SourceReference {
                     String sourceParameterName = segments[0];
                     parameter = method.getSourceParameter( sourceParameterName );
                     if ( parameter == null ) {
-                        reportMappingError( Message.PROPERTYMAPPING_INVALID_PARAMETER_NAME, sourceParameterName );
+                        reportMappingError(
+                            Message.PROPERTYMAPPING_INVALID_PARAMETER_NAME,
+                            sourceParameterName,
+                            Strings.join(
+                                method.getSourceParameters(),
+                                ", ",
+                                new Extractor<Parameter, String>() {
+                                    @Override
+                                    public String apply(Parameter parameter) {
+                                        return parameter.getName();
+                                    }
+                                }
+                            )
+                        );
                         isValid = false;
                     }
                 }

processor/src/main/java/org/mapstruct/ap/internal/util/Message.java

@@ -59,7 +59,7 @@ public enum Message {
     PROPERTYMAPPING_DEFAULT_VALUE_AND_DEFAULT_EXPRESSION_BOTH_DEFINED( "Default value and default expression are both defined in @Mapping, either define a default value or a default expression." ),
     PROPERTYMAPPING_INVALID_EXPRESSION( "Value for expression must be given in the form \"java(<EXPRESSION>)\"." ),
     PROPERTYMAPPING_INVALID_DEFAULT_EXPRESSION( "Value for default expression must be given in the form \"java(<EXPRESSION>)\"." ),
-    PROPERTYMAPPING_INVALID_PARAMETER_NAME( "Method has no parameter named \"%s\"." ),
+    PROPERTYMAPPING_INVALID_PARAMETER_NAME( "Method has no source parameter named \"%s\". Method source parameters are: \"%s\"." ),
     PROPERTYMAPPING_NO_PROPERTY_IN_PARAMETER( "The type of parameter \"%s\" has no property named \"%s\"." ),
     PROPERTYMAPPING_INVALID_PROPERTY_NAME( "No property named \"%s\" exists in source parameter(s). Did you mean \"%s\"?" ),
     PROPERTYMAPPING_NO_PRESENCE_CHECKER_FOR_SOURCE_TYPE( "Using custom source value presence checking strategy, but no presence checker found for %s in source type." ),

processor/src/main/java/org/mapstruct/ap/internal/util/Strings.java

@@ -98,10 +98,14 @@ public class Strings {
     }
 
     public static String join(Iterable<?> iterable, String separator) {
+        return join( iterable, separator, null );
+    }
+
+    public static <T> String join(Iterable<T> iterable, String separator, Extractor<T, String> extractor) {
         StringBuilder sb = new StringBuilder();
         boolean isFirst = true;
 
-        for ( Object object : iterable ) {
+        for ( T object : iterable ) {
             if ( !isFirst ) {
                 sb.append( separator );
             }
@@ -109,7 +113,7 @@ public class Strings {
                 isFirst = false;
             }
 
-            sb.append( object );
+            sb.append( extractor == null ? object : extractor.apply( object ) );
         }
 
         return sb.toString();

processor/src/test/java/org/mapstruct/ap/test/severalsources/ErroneousSourceTargetMapper2.java

@@ -0,0 +1,30 @@
+/**
+ *  Copyright 2012-2017 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.severalsources;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ErroneousSourceTargetMapper2 {
+
+    @Mapping( target = "houseNumber", source = "houseNo")
+    DeliveryAddress addressAndAddressToDeliveryAddress(Address address, Person person);
+}

processor/src/test/java/org/mapstruct/ap/test/severalsources/SeveralSourceParametersTest.java

@@ -168,4 +168,26 @@ public class SeveralSourceParametersTest {
     })
     public void shouldFailToGenerateMappingsForAmbigiousSourceProperty() {
     }
+
+    @Test
+    @WithClasses({
+        ErroneousSourceTargetMapper2.class,
+        Address.class,
+        Person.class,
+        DeliveryAddress.class
+    })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(
+                type = ErroneousSourceTargetMapper2.class,
+                kind = Kind.ERROR,
+                line = 28,
+                messageRegExp = "Method has no source parameter named \"houseNo\"\\." +
+                    " Method source parameters are: \"address, person\"\\."
+            )
+        }
+    )
+    public void shouldFailWhenSourcePropertyDoesNotMatchAnyOfTheSourceParameters() {
+    }
 }