Revise SpringExtension based on recent changes in JUnit Jupiter

This commit revises the implementation of the SpringExtension to use
the getRequired*() methods in the ExtensionContext which are now built
into JUnit Jupiter thanks to inspiration from the initial "convenience"
methods implemented here.

spring-test/src/main/java/org/springframework/test/context/junit/jupiter/SpringExtension.java

@@ -84,7 +84,7 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 			getTestContextManager(context).afterTestClass();
 		}
 		finally {
-			context.getStore(NAMESPACE).remove(getRequiredTestClass(context));
+			getStore(context).remove(context.getRequiredTestClass());
 		}
 	}
 
@@ -101,8 +101,8 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	 */
 	@Override
 	public void beforeEach(ExtensionContext context) throws Exception {
-		Object testInstance = getRequiredTestInstance(context);
-		Method testMethod = getRequiredTestMethod(context);
+		Object testInstance = context.getRequiredTestInstance();
+		Method testMethod = context.getRequiredTestMethod();
 		getTestContextManager(context).beforeTestMethod(testInstance, testMethod);
 	}
 
@@ -111,8 +111,8 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	 */
 	@Override
 	public void beforeTestExecution(ExtensionContext context) throws Exception {
-		Object testInstance = getRequiredTestInstance(context);
-		Method testMethod = getRequiredTestMethod(context);
+		Object testInstance = context.getRequiredTestInstance();
+		Method testMethod = context.getRequiredTestMethod();
 		getTestContextManager(context).beforeTestExecution(testInstance, testMethod);
 	}
 
@@ -121,8 +121,8 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	 */
 	@Override
 	public void afterTestExecution(ExtensionContext context) throws Exception {
-		Object testInstance = getRequiredTestInstance(context);
-		Method testMethod = getRequiredTestMethod(context);
+		Object testInstance = context.getRequiredTestInstance();
+		Method testMethod = context.getRequiredTestMethod();
 		Throwable testException = context.getExecutionException().orElse(null);
 		getTestContextManager(context).afterTestExecution(testInstance, testMethod, testException);
 	}
@@ -132,8 +132,8 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	 */
 	@Override
 	public void afterEach(ExtensionContext context) throws Exception {
-		Object testInstance = getRequiredTestInstance(context);
-		Method testMethod = getRequiredTestMethod(context);
+		Object testInstance = context.getRequiredTestInstance();
+		Method testMethod = context.getRequiredTestMethod();
 		Throwable testException = context.getExecutionException().orElse(null);
 		getTestContextManager(context).afterTestMethod(testInstance, testMethod, testException);
 	}
@@ -171,7 +171,7 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	@Nullable
 	public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
 		Parameter parameter = parameterContext.getParameter();
-		Class<?> testClass = getRequiredTestClass(extensionContext);
+		Class<?> testClass = extensionContext.getRequiredTestClass();
 		ApplicationContext applicationContext = getApplicationContext(extensionContext);
 		return ParameterAutowireUtils.resolveDependency(parameter, testClass, applicationContext);
 	}
@@ -194,45 +194,13 @@ public class SpringExtension implements BeforeAllCallback, AfterAllCallback, Tes
 	 */
 	private static TestContextManager getTestContextManager(ExtensionContext context) {
 		Assert.notNull(context, "ExtensionContext must not be null");
-		Class<?> testClass = getRequiredTestClass(context);
-		Store store = context.getStore(NAMESPACE);
+		Class<?> testClass = context.getRequiredTestClass();
+		Store store = getStore(context);
 		return store.getOrComputeIfAbsent(testClass, TestContextManager::new, TestContextManager.class);
 	}
 
-	/**
-	 * Get the test class associated with the supplied {@code ExtensionContext}.
-	 * @return the test class
-	 * @throws IllegalStateException if the extension context does not contain
-	 * a test class
-	 */
-	private static Class<?> getRequiredTestClass(ExtensionContext context) throws IllegalStateException {
-		Assert.notNull(context, "ExtensionContext must not be null");
-		return context.getTestClass().orElseThrow(
-			() -> new IllegalStateException("JUnit failed to supply the test class in the ExtensionContext"));
-	}
-
-	/**
-	 * Get the test instance associated with the supplied {@code ExtensionContext}.
-	 * @return the test instance
-	 * @throws IllegalStateException if the extension context does not contain
-	 * a test instance
-	 */
-	private static Object getRequiredTestInstance(ExtensionContext context) throws IllegalStateException {
-		Assert.notNull(context, "ExtensionContext must not be null");
-		return context.getTestInstance().orElseThrow(
-			() -> new IllegalStateException("JUnit failed to supply the test instance in the ExtensionContext"));
-	}
-
-	/**
-	 * Get the test method associated with the supplied {@code ExtensionContext}.
-	 * @return the test method
-	 * @throws IllegalStateException if the extension context does not contain
-	 * a test method
-	 */
-	private static Method getRequiredTestMethod(ExtensionContext context) throws IllegalStateException {
-		Assert.notNull(context, "ExtensionContext must not be null");
-		return context.getTestMethod().orElseThrow(
-			() -> new IllegalStateException("JUnit failed to supply the test method in the ExtensionContext"));
+	private static Store getStore(ExtensionContext context) {
+		return context.getRoot().getStore(NAMESPACE);
 	}
 
 }