Added builder for abstract entity

Author: michael-schnell

core/src/main/java/org/fuin/ddd4j/core/AbstractEntity.java

@@ -18,6 +18,7 @@
 package org.fuin.ddd4j.core;
 
 import org.fuin.objects4j.common.Contract;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Base class for entities.
@@ -65,7 +66,7 @@ public final int hashCode() {
     }
 
     @Override
-    public final boolean equals(final Object obj) {
+    public final boolean equals(@Nullable final Object obj) {
         if (this == obj) {
             return true;
         }
@@ -110,8 +111,10 @@ protected final ROOT_ID getRootId() {
      */
     protected abstract static class Builder<ROOT_ID extends AggregateRootId, ROOT extends AbstractAggregateRoot<ROOT_ID>, ID extends EntityId, TYPE extends AbstractEntity<ROOT_ID, ROOT, ID>, BUILDER extends Builder<ROOT_ID, ROOT, ID, TYPE, BUILDER>> {
 
+        @Nullable
         private ROOT rootAggregate;
 
+        @Nullable
         private ID id;
 
         /**
@@ -128,7 +131,7 @@ protected Builder() {
          * @return This builder.
          */
         @SuppressWarnings("unchecked")
-        public final BUILDER rootAggregate(@NotNull final ROOT rootAggregate) {
+        public final BUILDER rootAggregate(final ROOT rootAggregate) {
             Contract.requireArgNotNull("rootAggregate", rootAggregate);
             this.rootAggregate = rootAggregate;
             return (BUILDER) this;
@@ -141,7 +144,7 @@ public final BUILDER rootAggregate(@NotNull final ROOT rootAggregate) {
          * @return This builder.
          */
         @SuppressWarnings("unchecked")
-        public final BUILDER id(@NotNull final ID id) {
+        public final BUILDER id(final ID id) {
             Contract.requireArgNotNull("id", id);
             this.id = id;
             return (BUILDER) this;
@@ -152,6 +155,7 @@ public final BUILDER id(@NotNull final ID id) {
          *
          * @return Root aggregate.
          */
+        @Nullable
         protected final ROOT getRootAggregate() {
             return rootAggregate;
         }
@@ -161,6 +165,7 @@ protected final ROOT getRootAggregate() {
          *
          * @return Unique entity identifier.
          */
+        @Nullable
         protected final ID getEntityId() {
             return id;
         }
@@ -187,7 +192,7 @@ protected final void resetAbstractEntity() {
          * @param name  Name of the field.
          * @param value Value to test for {@literal null}.
          */
-        protected final void ensureNotNull(final String name, final Object value) {
+        protected final void ensureNotNull(final String name, @Nullable final Object value) {
             if (value == null) {
                 throw new RuntimeException("The value of '" + name + "' has not been set");
             }

core/src/test/java/org/fuin/ddd4j/core/AbstractEntityTest.java

@@ -23,9 +23,11 @@
 import org.fuin.ddd4j.coretest.ARoot;
 import org.fuin.ddd4j.coretest.BEntity;
 import org.fuin.ddd4j.coretest.BId;
+import org.fuin.objects4j.common.ConstraintViolationException;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 public class AbstractEntityTest {
 
@@ -50,4 +52,91 @@ public void testGetRootId() throws DuplicateEntityException {
 
     }
 
+    @Test
+    public void testBuilderBuild() {
+
+        // PREPARE
+        final ARoot root = new ARoot(new AId(1));
+        final BId id = new BId(2);
+
+        // TEST
+        final BEntity entity = new BEntityBuilder().rootAggregate(root).id(id).build();
+
+        // VERIFY
+        assertThat(entity).isNotNull();
+        assertThat(entity.getRoot()).isEqualTo(root);
+        assertThat(entity.getId()).isEqualTo(id);
+
+    }
+
+    @Test
+    public void testBuilderReturnsItself() {
+
+        // PREPARE
+        final BEntityBuilder builder = new BEntityBuilder();
+
+        // TEST & VERIFY
+        assertThat(builder.rootAggregate(new ARoot(new AId(1)))).isSameAs(builder);
+        assertThat(builder.id(new BId(2))).isSameAs(builder);
+
+    }
+
+    @Test
+    public void testBuilderRootAggregateNull() {
+        assertThatThrownBy(() -> new BEntityBuilder().rootAggregate(null))
+                .isInstanceOf(ConstraintViolationException.class)
+                .hasMessageContaining("rootAggregate");
+    }
+
+    @Test
+    public void testBuilderIdNull() {
+        assertThatThrownBy(() -> new BEntityBuilder().id(null))
+                .isInstanceOf(ConstraintViolationException.class)
+                .hasMessageContaining("id");
+    }
+
+    @Test
+    public void testBuilderEnsureBuildableFailsWhenRootAggregateMissing() {
+        assertThatThrownBy(() -> new BEntityBuilder().id(new BId(2)).build())
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("rootAggregate");
+    }
+
+    @Test
+    public void testBuilderEnsureBuildableFailsWhenIdMissing() {
+        assertThatThrownBy(() -> new BEntityBuilder().rootAggregate(new ARoot(new AId(1))).build())
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("id");
+    }
+
+    @Test
+    public void testBuilderResetsAfterBuild() {
+
+        // PREPARE
+        final BEntityBuilder builder = new BEntityBuilder();
+        builder.rootAggregate(new ARoot(new AId(1))).id(new BId(2)).build();
+
+        // TEST & VERIFY - the mandatory data was cleared, so a second build fails
+        assertThatThrownBy(builder::build)
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("rootAggregate");
+
+    }
+
+    /**
+     * Concrete builder used to test the abstract {@link AbstractEntity.Builder}.
+     */
+    private static final class BEntityBuilder
+            extends AbstractEntity.Builder<AId, ARoot, BId, BEntity, BEntityBuilder> {
+
+        @Override
+        public BEntity build() {
+            ensureBuildableAbstractEntity();
+            final BEntity entity = new BEntity(getRootAggregate(), getEntityId());
+            resetAbstractEntity();
+            return entity;
+        }
+
+    }
+
 }

pom.xml

@@ -29,6 +29,7 @@
     </issueManagement>
 
     <properties>
+
         <jackson.version>2.18.2</jackson.version>
         <esc.version>0.10.0-SNAPSHOT</esc.version>
         <objects4j.version>0.11.1-SNAPSHOT</objects4j.version>
@@ -39,6 +40,7 @@
         <org-fuin-bom.version>1.0.2-SNAPSHOT</org-fuin-bom.version>
         <error-prone.version>2.49.0</error-prone.version>
         <nullaway.version>0.13.6</nullaway.version>
+
     </properties>
 
     <dependencyManagement>