test: Add comprehensive edge case and validation tests for runtime hints registration (spring-projects#4028)

Adds 4 targeted test cases to strengthen runtime hints functionality across multiple components:

- ToolRuntimeHintsTests:

Null ClassLoader handling - Ensures tool hints registration doesn't fail when ClassLoader parameter is null (common in AOT processing)

- AiRuntimeHintsTests:

Record validation - Confirms records with @JsonProperty parameters are properly discovered for hint registration
Enum validation - Verifies enums with @JsonInclude annotations are correctly identified for reflection hints

- JdbcChatMemoryRepositoryRuntimeHintsTest:

Null ClassLoader robustness - Validates JDBC chat memory hints registration handles null ClassLoader gracefully
These tests prevent runtime failures in native images by ensuring proper discovery of JSON-annotated classes (records/enums), robust hint registration under various ClassLoader conditions, and reliable chat memory persistence in GraalVM environments.

Signed-off-by: Alex Klimenko <alexanderklmn@gmail.com>

Author: alxkm

memory/repository/spring-ai-model-chat-memory-repository-jdbc/src/test/java/org/springframework/ai/chat/memory/repository/jdbc/aot/hint/JdbcChatMemoryRepositoryRuntimeHintsTest.java

@@ -34,6 +34,7 @@
 import org.springframework.core.io.support.SpringFactoriesLoader;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatNoException;
 
 /**
  * @author Jonathan Leijendekker
@@ -72,6 +73,12 @@ void dataSourceHasHints() {
 		assertThat(RuntimeHintsPredicates.reflection().onType(DataSource.class)).accepts(this.hints);
 	}
 
+	@Test
+	void registerHintsWithNullClassLoader() {
+		assertThatNoException()
+			.isThrownBy(() -> this.jdbcChatMemoryRepositoryRuntimeHints.registerHints(this.hints, null));
+	}
+
 	private static Stream<String> getSchemaFileNames() throws IOException {
 		var resources = new PathMatchingResourcePatternResolver()
 			.getResources("classpath*:org/springframework/ai/chat/memory/repository/jdbc/schema-*.sql");

spring-ai-model/src/test/java/org/springframework/ai/aot/AiRuntimeHintsTests.java

@@ -27,10 +27,12 @@
 import org.springframework.aot.hint.TypeReference;
 import org.springframework.util.Assert;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 class AiRuntimeHintsTests {
 
 	@Test
-	void discoverRelevantClasses() throws Exception {
+	void discoverRelevantClasses() {
 		var classes = AiRuntimeHints.findJsonAnnotatedClassesInPackage(TestApi.class);
 		var included = Set.of(TestApi.Bar.class, TestApi.Foo.class)
 			.stream()
@@ -40,6 +42,24 @@ void discoverRelevantClasses() throws Exception {
 		Assert.state(classes.containsAll(included), "there should be all of the enumerated classes. ");
 	}
 
+	@Test
+	void verifyRecordWithJsonPropertyIncluded() {
+		var classes = AiRuntimeHints.findJsonAnnotatedClassesInPackage(TestApi.class);
+
+		// Foo record should be included due to @JsonProperty on parameter
+		var recordClass = TypeReference.of(TestApi.Foo.class.getName());
+		assertThat(classes).contains(recordClass);
+	}
+
+	@Test
+	void verifyEnumWithJsonIncludeAnnotation() {
+		var classes = AiRuntimeHints.findJsonAnnotatedClassesInPackage(TestApi.class);
+
+		// Bar enum should be included due to @JsonInclude
+		var enumClass = TypeReference.of(TestApi.Bar.class.getName());
+		assertThat(classes).contains(enumClass);
+	}
+
 	@JsonInclude
 	static class TestApi {
 

spring-ai-model/src/test/java/org/springframework/ai/aot/ToolRuntimeHintsTests.java

@@ -22,6 +22,7 @@
 import org.springframework.aot.hint.RuntimeHints;
 
 import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
 import static org.springframework.aot.hint.predicate.RuntimeHintsPredicates.reflection;
 
 /**
@@ -37,4 +38,13 @@ void registerHints() {
 		assertThat(runtimeHints).matches(reflection().onType(DefaultToolCallResultConverter.class));
 	}
 
+	@Test
+	void registerHintsWithNullClassLoader() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		ToolRuntimeHints toolRuntimeHints = new ToolRuntimeHints();
+
+		// Should not throw exception with null ClassLoader
+		assertThatCode(() -> toolRuntimeHints.registerHints(runtimeHints, null)).doesNotThrowAnyException();
+	}
+
 }