Add missing unit tests for SimpleAliasRegistry

Closes gh-31348

Author: e-freni

spring-core/src/test/java/org/springframework/core/SimpleAliasRegistryTests.java

@@ -18,7 +18,13 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.util.StringValueResolver;
+
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.mock;
 
 /**
  * Unit tests for {@link SimpleAliasRegistry}.
@@ -43,6 +49,7 @@ void aliasChaining() {
 		assertThat(registry.canonicalName("testAlias")).isEqualTo("test");
 		assertThat(registry.canonicalName("testAlias2")).isEqualTo("test");
 		assertThat(registry.canonicalName("testAlias3")).isEqualTo("test");
+
 	}
 
 	@Test  // SPR-17191
@@ -95,4 +102,52 @@ void getAliases() {
 		assertThat(registry.getAliases("testAlias3")).isEmpty();
 	}
 
+	@Test
+	void testCheckForAliasCircle() {
+		String name = "testName";
+		String alias = "testAlias";
+		registry.checkForAliasCircle(name, alias);
+		registry.registerAlias(name, alias);
+		assertThatIllegalStateException()
+				.isThrownBy(() -> registry.checkForAliasCircle(alias, name));
+	}
+
+	@Test
+	void testResolveAliases() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> registry.resolveAliases(null));
+
+		StringValueResolver mock = mock();
+
+		registry.registerAlias("testName1", "testAlias1");
+		registry.registerAlias("testName2", "testAlias2");
+		given(mock.resolveStringValue("testAlias2")).willReturn("anotherAlias2");
+		given(mock.resolveStringValue("testName2")).willReturn("anotherName2");
+		registry.resolveAliases(mock);
+		assertThat(registry.getAliases("anotherName2")).containsExactly("anotherAlias2");
+
+		registry.registerAlias("testName3", "testAlias3");
+		registry.registerAlias("testName4", "testAlias4");
+		registry.registerAlias("testName5", "testAlias5");
+		given(mock.resolveStringValue("testName5")).willReturn("testName5");
+		given(mock.resolveStringValue("testAlias5")).willReturn("testAlias5");
+		given(mock.resolveStringValue("testName3")).willReturn("testName4");
+		given(mock.resolveStringValue("testAlias3")).willReturn("testAlias4");
+		given(mock.resolveStringValue("testName4")).willReturn("testName4");
+		given(mock.resolveStringValue("testAlias4")).willReturn("testAlias5");
+		assertThatIllegalStateException()
+				.isThrownBy(() -> registry.resolveAliases(mock));
+
+		given(mock.resolveStringValue("testName4")).willReturn("testName5");
+		given(mock.resolveStringValue("testAlias4")).willReturn("testAlias4");
+		assertThatIllegalStateException()
+				.isThrownBy(() -> registry.resolveAliases(mock));
+
+		given(mock.resolveStringValue("testName4")).willReturn("testName4");
+		given(mock.resolveStringValue("testAlias4")).willReturn("testAlias5");
+		registry.resolveAliases(mock);
+		assertThat(registry.getAliases("testName4")).containsExactly("testAlias4");
+		assertThat(registry.getAliases("testName5")).containsExactly("testAlias5");
+	}
+
 }