Allow custom TestRestTemplate beans

Update `@SpringBootTest` `TestRestTemplate` support so that the bean
definition is only registered when the user has not defined or
auto-configured their own.

See gh-10556

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

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2018 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.boot.test.web.client;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.BeanFactoryAware;
+import org.springframework.beans.factory.BeanFactoryUtils;
+import org.springframework.beans.factory.ListableBeanFactory;
+import org.springframework.context.annotation.ImportSelector;
+import org.springframework.core.type.AnnotationMetadata;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * {@link ImportSelector} to check no {@link TestRestTemplate} definition is registered
+ * when config classes are processed.
+ */
+class NoTestRestTemplateBeanChecker implements ImportSelector, BeanFactoryAware {
+
+	@Override
+	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
+		assertThat(BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
+				(ListableBeanFactory) beanFactory, TestRestTemplate.class)).isEmpty();
+	}
+
+	@Override
+	public String[] selectImports(AnnotationMetadata importingClassMetadata) {
+		return new String[0];
+	}
+
+}

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

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2012-2018 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.boot.test.web.client;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import javax.servlet.GenericServlet;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+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.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration test for {@link TestRestTemplateTestContextCustomizer}.
+ *
+ * @author Phillip Webb
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@DirtiesContext
+public class TestRestTemplateTestContextCustomizerIntegrationTests {
+
+	@Autowired
+	private TestRestTemplate restTemplate;
+
+	@Test
+	public void test() {
+		assertThat(this.restTemplate.getForObject("/", String.class)).contains("hello");
+	}
+
+	@Configuration
+	@Import({ TestServlet.class, NoTestRestTemplateBeanChecker.class })
+	static class TestConfig {
+
+		@Bean
+		public TomcatServletWebServerFactory webServerFactory() {
+			return new TomcatServletWebServerFactory(0);
+		}
+
+	}
+
+	static class TestServlet extends GenericServlet {
+
+		@Override
+		public void service(ServletRequest request, ServletResponse response)
+				throws ServletException, IOException {
+			try (PrintWriter writer = response.getWriter()) {
+				writer.println("hello");
+			}
+		}
+
+	}
+
+}

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

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2012-2018 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.boot.test.web.client;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import javax.servlet.GenericServlet;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+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.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration test for {@link TestRestTemplateTestContextCustomizer} with a custom
+ * {@link TestRestTemplate} bean.
+ *
+ * @author Phillip Webb
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@DirtiesContext
+public class TestRestTemplateTestContextCustomizerWithOverrideIntegrationTests {
+
+	@Autowired
+	private TestRestTemplate restTemplate;
+
+	@Test
+	public void test() {
+		assertThat(this.restTemplate).isInstanceOf(CustomTestRestTemplate.class);
+	}
+
+	@Configuration
+	@Import({ TestServlet.class, NoTestRestTemplateBeanChecker.class })
+	static class TestConfig {
+
+		@Bean
+		public TomcatServletWebServerFactory webServerFactory() {
+			return new TomcatServletWebServerFactory(0);
+		}
+
+		@Bean
+		public TestRestTemplate template() {
+			return new CustomTestRestTemplate();
+		}
+
+	}
+
+	static class TestServlet extends GenericServlet {
+
+		@Override
+		public void service(ServletRequest request, ServletResponse response)
+				throws ServletException, IOException {
+			try (PrintWriter writer = response.getWriter()) {
+				writer.println("hello");
+			}
+		}
+
+	}
+
+	static class CustomTestRestTemplate extends TestRestTemplate {
+
+	}
+
+}