Introduce tests for @nested tests in JUnit Jupiter

This commit introduces integration tests that verify the expected
behavior for @nested tests in conjunction with the SpringExtension for
JUnit Jupiter, including automatic application of
TestExecutionListeners to the enclosing test instance of a @nested
test instance.

Issue: SPR-14150

Author: sbrannen

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

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2002-2016 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
+ *
+ *      http://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.test.context.junit.jupiter.nested;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+import org.springframework.test.context.junit.jupiter.nested.NestedTestsWithSpringAndJUnitJupiterTestCase.TopLevelConfig;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Integration tests that verify support for {@code @Nested} test classes
+ * in conjunction with the {@link SpringExtension} in a JUnit 5 (Jupiter)
+ * environment.
+ * 
+ * @author Sam Brannen
+ * @since 5.0
+ * @see org.springframework.test.context.junit4.nested.NestedTestsWithSpringRulesTests
+ */
+@SpringJUnitConfig(TopLevelConfig.class)
+class NestedTestsWithSpringAndJUnitJupiterTestCase {
+
+	@Autowired
+	String foo;
+
+
+	@Test
+	void topLevelTest() {
+		assertEquals("foo", foo);
+	}
+
+
+	@Nested
+	@SpringJUnitConfig(NestedConfig.class)
+	class NestedTestCase {
+
+		@Autowired
+		String bar;
+
+
+		@Test
+		void nestedTest() throws Exception {
+			// In contrast to nested test classes running in JUnit 4, the foo
+			// field in the outer instance should have been injected from the
+			// test ApplicationContext for the outer instance.
+			assertEquals("foo", foo);
+			assertEquals("bar", bar);
+		}
+	}
+
+	// -------------------------------------------------------------------------
+
+	@Configuration
+	public static class TopLevelConfig {
+
+		@Bean
+		String foo() {
+			return "foo";
+		}
+	}
+
+	@Configuration
+	static class NestedConfig {
+
+		@Bean
+		String bar() {
+			return "bar";
+		}
+	}
+
+}

spring-test/src/test/java/org/springframework/test/context/junit4/nested/NestedTestsWithSpringRulesTests.java

@@ -39,6 +39,7 @@
  *
  * @author Sam Brannen
  * @since 5.0
+ * @see org.springframework.test.context.junit.jupiter.nested.NestedTestsWithSpringAndJUnitJupiterTestCase
  */
 @RunWith(HierarchicalContextRunner.class)
 @ContextConfiguration(classes = TopLevelConfig.class)