Prevent early initialization of factory beans in text context customizers

Until Spring Framework 5.1.15, a FactoryBean with a non-default constructor
defined via component scanning would cause an error. This behavior has changed
as of https://github.com/spring-projects/spring-framework/issues/22409.
Regardless of this change we want to ensure that we avoid triggering eager
initialisation. `SimpleFactoryBean` has been written this way so that the tests
fail if early initialization is triggered regardless of the Spring Framework version.

Fixes gh-15898

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/web/client/TestRestTemplateContextCustomizer.java

@@ -111,8 +111,8 @@ class TestRestTemplateContextCustomizer implements ContextCustomizer {
 		public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry)
 				throws BeansException {
 			if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
-					(ListableBeanFactory) this.beanFactory,
+					(ListableBeanFactory) this.beanFactory, TestRestTemplate.class, false,
-					TestRestTemplate.class).length == 0) {
+					false).length == 0) {
 				registry.registerBeanDefinition(TestRestTemplate.class.getName(),
 						new RootBeanDefinition(TestRestTemplateFactory.class));
 			}

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/web/reactive/server/WebTestClientContextCustomizer.java

@@ -111,8 +111,8 @@ class WebTestClientContextCustomizer implements ContextCustomizer {
 		public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry)
 				throws BeansException {
 			if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
-					(ListableBeanFactory) this.beanFactory,
+					(ListableBeanFactory) this.beanFactory, WebTestClient.class, false,
-					WebTestClient.class).length == 0) {
+					false).length == 0) {
 				registry.registerBeanDefinition(WebTestClient.class.getName(),
 						new RootBeanDefinition(WebTestClientFactory.class));
 			}

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/web/client/TestRestTemplateContextCustomizerWithFactoryBeanTests.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2012-2019 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.boot.test.web.client;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringRunner;
+
+/**
+ * Integration tests for {@link TestRestTemplateContextCustomizer} to ensure
+ * early-initialization of factory beans doesn't occur.
+ *
+ * @author Madhura Bhave
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = TestRestTemplateContextCustomizerWithFactoryBeanTests.TestClassWithFactoryBean.class, webEnvironment = WebEnvironment.RANDOM_PORT)
+@DirtiesContext
+public class TestRestTemplateContextCustomizerWithFactoryBeanTests {
+
+	@Autowired
+	private TestRestTemplate restTemplate;
+
+	@Test
+	public void test() {
+	}
+
+	@Configuration
+	@ComponentScan("org.springframework.boot.test.web.client.scan")
+	static class TestClassWithFactoryBean {
+
+		@Bean
+		public TomcatServletWebServerFactory webServerFactory() {
+			return new TomcatServletWebServerFactory(0);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/web/client/scan/SimpleFactoryBean.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2012-2019 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.boot.test.web.client.scan;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationContext;
+import org.springframework.stereotype.Component;
+
+/**
+ * @author Madhura Bhave
+ */
+@Component
+public class SimpleFactoryBean implements FactoryBean {
+
+	private static boolean isInitializedEarly = false;
+
+	public SimpleFactoryBean() {
+		isInitializedEarly = true;
+		throw new RuntimeException();
+	}
+
+	@Autowired
+	public SimpleFactoryBean(ApplicationContext context) {
+		if (isInitializedEarly) {
+			throw new RuntimeException();
+		}
+	}
+
+	public Object getObject() {
+		return new Object();
+	}
+
+	public Class<?> getObjectType() {
+		return Object.class;
+	}
+
+}