Fix cast in TestRestTemplateContextCustomizer

Closes gh-15843

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

@@ -62,7 +62,7 @@ class TestRestTemplateContextCustomizer implements ContextCustomizer {
 	private void registerTestRestTemplate(ConfigurableApplicationContext context) {
 		ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
 		if (beanFactory instanceof BeanDefinitionRegistry) {
-			registerTestRestTemplate((BeanDefinitionRegistry) context);
+			registerTestRestTemplate((BeanDefinitionRegistry) beanFactory);
 		}
 	}
 

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

@@ -0,0 +1,82 @@
+/*
+ * 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
+ *
+ *      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.junit.Test;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.test.context.MergedContextConfiguration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link TestRestTemplateContextCustomizer}.
+ *
+ * @author Andy Wilkinson
+ */
+public class TestRestTemplateContextCustomizerTests {
+
+	@Test
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public void whenContextIsNotABeanDefinitionRegistryTestRestTemplateIsRegistered() {
+		new ApplicationContextRunner(TestApplicationContext::new)
+				.withInitializer((context) -> {
+					MergedContextConfiguration configuration = mock(
+							MergedContextConfiguration.class);
+					given(configuration.getTestClass())
+							.willReturn((Class) TestClass.class);
+					new TestRestTemplateContextCustomizer().customizeContext(context,
+							configuration);
+				}).run((context) -> assertThat(context)
+						.hasSingleBean(TestRestTemplate.class));
+	}
+
+	@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+	static class TestClass {
+
+	}
+
+	private static class TestApplicationContext extends AbstractApplicationContext {
+
+		private final ConfigurableListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+
+		@Override
+		protected void refreshBeanFactory() throws BeansException, IllegalStateException {
+		}
+
+		@Override
+		protected void closeBeanFactory() {
+
+		}
+
+		@Override
+		public ConfigurableListableBeanFactory getBeanFactory()
+				throws IllegalStateException {
+			return this.beanFactory;
+		}
+
+	}
+
+}