Resolve all default context configuration within test class hierarchies

Prior to this commit, if a superclass or enclosing test class (such as
one annotated with @⁠SpringBootTest or simply
@⁠ExtendWith(SpringExtension.class)) was not annotated with
@⁠ContextConfiguration (or @⁠Import with @⁠SpringBootTest), the
ApplicationContext loaded for a subclass or @⁠Nested test class would
not use any default context configuration for the superclass or
enclosing test class.

Effectively, a default XML configuration file or static nested
@⁠Configuration class for the superclass or enclosing test class was
not discovered by the AbstractTestContextBootstrapper when attempting
to build the MergedContextConfiguration (application context cache key).

To address that, this commit introduces a new
resolveDefaultContextConfigurationAttributes() method in
ContextLoaderUtils which is responsible for creating instances of
ContextConfigurationAttributes for all superclasses and enclosing
classes. This effectively enables AbstractTestContextBootstrapper to
delegate to the resolved SmartContextLoader to properly detect a
default XML configuration file or static nested @⁠Configuration class
even if such classes are not annotated with @⁠ContextConfiguration.

Closes gh-31456

spring-test/src/test/java/org/springframework/test/context/config/ImplicitDefaultConfigClassesBaseTests.java

@@ -46,7 +46,7 @@ class ImplicitDefaultConfigClassesBaseTests {
 
 
 	@Test
-	void greeting1AndPuzzle1() {
+	final void greeting1AndPuzzle1() {
 		// This class must NOT be annotated with @SpringJUnitConfig or @ContextConfiguration.
 		assertThat(AnnotatedElementUtils.hasAnnotation(getClass(), ContextConfiguration.class)).isFalse();
 

spring-test/src/test/java/org/springframework/test/context/config/ImplicitDefaultConfigClassesInheritedTests.java

@@ -41,14 +41,6 @@ class ImplicitDefaultConfigClassesInheritedTests extends ImplicitDefaultConfigCl
 	String greeting2;
 
 
-	// To be removed in favor of base class method in 7.1
-	@Test
-	@Override
-	void greeting1AndPuzzle1() {
-		assertThat(greeting1).isEqualTo("TEST 2");
-		assertThat(puzzle1).isEqualTo(222);
-	}
-
 	@Test
 	void greeting2() {
 		// This class must NOT be annotated with @SpringJUnitConfig or @ContextConfiguration.
@@ -59,8 +51,7 @@ class ImplicitDefaultConfigClassesInheritedTests extends ImplicitDefaultConfigCl
 
 	@Test
 	void greetings(@Autowired List<String> greetings) {
-		assertThat(greetings).containsExactly("TEST 2");
-		// for 7.1: assertThat(greetings).containsExactly("TEST 1", "TEST 2");
+		assertThat(greetings).containsExactly("TEST 1", "TEST 2");
 	}
 
 

spring-test/src/test/java/org/springframework/test/context/junit/jupiter/nested/DefaultContextConfigurationDetectionWithNestedTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.test.context.junit.jupiter.nested;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
@@ -53,7 +54,6 @@ class DefaultContextConfigurationDetectionWithNestedTests {
 	}
 
 
-	/** for 7.1:
 	@Nested
 	class NestedTests {
 
@@ -63,7 +63,6 @@ class DefaultContextConfigurationDetectionWithNestedTests {
 			assertThat(localGreeting).isEqualTo("TEST");
 		}
 	}
-	*/
 
 
 	@Configuration