Add coverage for nulls and error propagation

Author: RanVaknin

services-custom/dynamodb-enhanced/src/test/java/software/amazon/awssdk/enhanced/dynamodb/mapper/ImmutableAttributeTest.java

@@ -29,6 +29,7 @@
 import org.mockito.junit.MockitoJUnitRunner;
 import software.amazon.awssdk.enhanced.dynamodb.AttributeConverter;
 import software.amazon.awssdk.enhanced.dynamodb.AttributeConverterProvider;
+import software.amazon.awssdk.enhanced.dynamodb.AttributeValueType;
 import software.amazon.awssdk.enhanced.dynamodb.EnhancedType;
 import software.amazon.awssdk.enhanced.dynamodb.internal.mapper.ResolvedImmutableAttribute;
 import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
@@ -229,4 +230,43 @@ public void resolve_uses_customConverter() {
 
         assertThat(resultAttributeValue.s()).isEqualTo("test-string-custom");
     }
+
+    @Test
+    public void getAttributeValue_getterThrowsRuntimeException_propagatesException() {
+        ImmutableAttribute<SimpleItem, SimpleItem, String> staticAttribute =
+            ImmutableAttribute.builder(SimpleItem.class, SimpleItem.class, String.class)
+                              .name("test-attribute")
+                              .getter(item -> { throw new RuntimeException("getter failed"); })
+                              .setter(SimpleItem::setAString)
+                              .build();
+
+        ResolvedImmutableAttribute<SimpleItem, SimpleItem, String> resolvedAttribute =
+            staticAttribute.resolve(AttributeConverterProvider.defaultProvider());
+
+        Function<SimpleItem, AttributeValue> attributeValueFunction = resolvedAttribute.attributeGetterMethod();
+        SimpleItem item = new SimpleItem("test");
+
+        assertThatThrownBy(() -> attributeValueFunction.apply(item))
+            .isInstanceOf(RuntimeException.class)
+            .hasMessage("getter failed");
+    }
+
+    @Test
+    public void getAttributeValue_nullFromGetter_returnsNullAttributeValue() {
+        ImmutableAttribute<SimpleItem, SimpleItem, String> staticAttribute =
+            ImmutableAttribute.builder(SimpleItem.class, SimpleItem.class, String.class)
+                              .name("test-attribute")
+                              .getter(item -> null)
+                              .setter(SimpleItem::setAString)
+                              .build();
+
+        ResolvedImmutableAttribute<SimpleItem, SimpleItem, String> resolvedAttribute =
+            staticAttribute.resolve(AttributeConverterProvider.defaultProvider());
+
+        Function<SimpleItem, AttributeValue> attributeValueFunction = resolvedAttribute.attributeGetterMethod();
+        SimpleItem item = new SimpleItem("test");
+        AttributeValue result = attributeValueFunction.apply(item);
+
+        assertThat(result.nul()).isTrue();
+    }
 }