Validate class name input in SimpleTypeReference

Closes gh-28213

spring-core/src/test/java/org/springframework/aot/hint/SimpleTypeReferenceTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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.springframework.aot.hint;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+
+/**
+ * Tests for {@link SimpleTypeReference}.
+ *
+ * @author Stephane Nicoll
+ */
+class SimpleTypeReferenceTests {
+
+	@Test
+	void typeReferenceInRootPackage() {
+		TypeReference type = SimpleTypeReference.of("MyRootClass");
+		assertThat(type.getCanonicalName()).isEqualTo("MyRootClass");
+		assertThat(type.getPackageName()).isEqualTo("");
+	}
+
+	@ParameterizedTest(name = "{0}")
+	@ValueSource(strings = { "com.example.Tes(t", "com.example..Test" })
+	void typeReferenceWithInvalidClassName(String invalidClassName) {
+		assertThatIllegalStateException().isThrownBy(() -> SimpleTypeReference.of(invalidClassName))
+				.withMessageContaining("Invalid class name");
+	}
+
+}