#3943: Added negative test.

mapstruct · anenviousguest · Oct 15, 2025 · Oct 15, 2025 · Feb 28, 2026 · Feb 28, 2026
commit daa1c2d1c38364abd7dc4e9258586d9817d0709e
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943ErroneousMapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943ErroneousMapper.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._3943;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR)
+public interface Issue3943ErroneousMapper {
+
+    Issue3943ErroneousMapper INSTANCE = Mappers.getMapper( Issue3943ErroneousMapper.class );
+
+    Target map(int somethingElse);
+
+    class Target {
+
+        private final int value;
+
+        public Target(int value) {
+            this.value = value;
+        }
+
+        public int getValue() {
+            return value;
+        }
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943Mapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943Mapper.java
@@ -16,6 +16,8 @@ public interface Issue3943Mapper {
 
     TargetWithMatchingProperty mapImplicitly(int value);
 
+//    TargetWithMatchingProperty mapImplicitlyWithoutMatchingProperty(int somethingElse);
+
     @Mapping(target = "value", source = "value")
     TargetWithMatchingProperty mapWithMatchingProperty(int value);
 
@@ -24,26 +26,26 @@ public interface Issue3943Mapper {
 
     class TargetWithMatchingProperty {
 
-        private final long value;
+        private final int value;
 
-        public TargetWithMatchingProperty(long value) {
+        public TargetWithMatchingProperty(int value) {
             this.value = value;
         }
 
-        public long getValue() {
+        public int getValue() {
             return value;
         }
     }
 
     class TargetWithoutMatchingProperty {
 
-        private final long nonMatchingProperty;
+        private final int nonMatchingProperty;
 
-        public TargetWithoutMatchingProperty(long nonMatchingProperty) {
+        public TargetWithoutMatchingProperty(int nonMatchingProperty) {
             this.nonMatchingProperty = nonMatchingProperty;
         }
 
-        public long getNonMatchingProperty() {
+        public int getNonMatchingProperty() {
             return nonMatchingProperty;
         }
     }

diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3943/Issue3943Test.java
@@ -5,9 +5,12 @@
  */
 package org.mapstruct.ap.test.bugs._3943;
 
+import javax.tools.Diagnostic.Kind;
+
 import org.mapstruct.ap.testutil.IssueKey;
 import org.mapstruct.ap.testutil.ProcessorTest;
 import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.compilation.annotation.*;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -35,4 +38,18 @@ void shouldGenerateValidCodeForBeanWithoutMatchingProperty() {
         assertThat( target ).isNotNull();
         assertThat( target.getNonMatchingProperty() ).isEqualTo( 42L );
     }
+
+    @ProcessorTest
+    @WithClasses( { Issue3943ErroneousMapper.class } )
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = Issue3943ErroneousMapper.class,
+                kind = Kind.ERROR,
+                line = 16,
+                message = "Unmapped target property: \"value\"." )
+        }
+    )
+    void shouldFailToGenerateCodeIfPropertyNameDoesNotMatch() {
+    }
 }