Fix handling of UriTemplateRequestEntity in TestRestTemplate

A change [1] in Spring Framework 5.3 means that getUrl() on a
RequestEntity will throw an UnsupportedOperationException if the
entity was created using a template.

This commit updates TestRestTemplate to check for instances of
UriTemplateRequestEntity and to resolve the URI using the
entity's UriTemplateHandler instead of calling getUrl() directly.

Fixes gh-25097

[1] spring-projects/spring-framework@a0f4d81

Author: wilkinsona

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -41,6 +41,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.RequestEntity;
+import org.springframework.http.RequestEntity.UriTemplateRequestEntity;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.http.client.ClientHttpResponse;
@@ -965,7 +966,7 @@ public TestRestTemplate withBasicAuth(String username, String password) {
 	@SuppressWarnings({ "rawtypes", "unchecked" })
 	private RequestEntity<?> createRequestEntityWithRootAppliedUri(RequestEntity<?> requestEntity) {
 		return new RequestEntity(requestEntity.getBody(), requestEntity.getHeaders(), requestEntity.getMethod(),
-				applyRootUriIfNecessary(requestEntity.getUrl()), requestEntity.getType());
+				applyRootUriIfNecessary(resolveUri(requestEntity)), requestEntity.getType());
 	}
 
 	private URI applyRootUriIfNecessary(URI uri) {
@@ -976,6 +977,23 @@ private URI applyRootUriIfNecessary(URI uri) {
 		return uri;
 	}
 
+	private URI resolveUri(RequestEntity<?> entity) {
+		if (entity instanceof UriTemplateRequestEntity) {
+			UriTemplateRequestEntity<?> templatedUriEntity = (UriTemplateRequestEntity<?>) entity;
+			if (templatedUriEntity.getVars() != null) {
+				return this.restTemplate.getUriTemplateHandler().expand(templatedUriEntity.getUriTemplate(),
+						templatedUriEntity.getVars());
+			}
+			else if (templatedUriEntity.getVarsMap() != null) {
+				return this.restTemplate.getUriTemplateHandler().expand(templatedUriEntity.getUriTemplate(),
+						templatedUriEntity.getVarsMap());
+			}
+			throw new IllegalStateException(
+					"No variables specified for URI template: " + templatedUriEntity.getUriTemplate());
+		}
+		return entity.getUrl();
+	}
+
 	/**
 	 * Options used to customize the Apache HTTP Client.
 	 */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -233,6 +233,36 @@ void withBasicAuthShouldUseNoOpErrorHandler() throws Exception {
 				Class.forName("org.springframework.boot.test.web.client.TestRestTemplate$NoOpResponseErrorHandler"));
 	}
 
+	@Test
+	void exchangeWithRelativeTemplatedUrlRequestEntity() throws Exception {
+		RequestEntity<Void> entity = RequestEntity.get("/a/b/c.{ext}", "txt").build();
+		TestRestTemplate template = new TestRestTemplate();
+		ClientHttpRequestFactory requestFactory = mock(ClientHttpRequestFactory.class);
+		MockClientHttpRequest request = new MockClientHttpRequest();
+		request.setResponse(new MockClientHttpResponse(new byte[0], HttpStatus.OK));
+		URI absoluteUri = URI.create("http://localhost:8080/a/b/c.txt");
+		given(requestFactory.createRequest(eq(absoluteUri), eq(HttpMethod.GET))).willReturn(request);
+		template.getRestTemplate().setRequestFactory(requestFactory);
+		LocalHostUriTemplateHandler uriTemplateHandler = new LocalHostUriTemplateHandler(new MockEnvironment());
+		template.setUriTemplateHandler(uriTemplateHandler);
+		template.exchange(entity, String.class);
+		verify(requestFactory).createRequest(eq(absoluteUri), eq(HttpMethod.GET));
+	}
+
+	@Test
+	void exchangeWithAbsoluteTemplatedUrlRequestEntity() throws Exception {
+		RequestEntity<Void> entity = RequestEntity.get("https://api.example.com/a/b/c.{ext}", "txt").build();
+		TestRestTemplate template = new TestRestTemplate();
+		ClientHttpRequestFactory requestFactory = mock(ClientHttpRequestFactory.class);
+		MockClientHttpRequest request = new MockClientHttpRequest();
+		request.setResponse(new MockClientHttpResponse(new byte[0], HttpStatus.OK));
+		URI absoluteUri = URI.create("https://api.example.com/a/b/c.txt");
+		given(requestFactory.createRequest(eq(absoluteUri), eq(HttpMethod.GET))).willReturn(request);
+		template.getRestTemplate().setRequestFactory(requestFactory);
+		template.exchange(entity, String.class);
+		verify(requestFactory).createRequest(eq(absoluteUri), eq(HttpMethod.GET));
+	}
+
 	@Test
 	void deleteHandlesRelativeUris() throws IOException {
 		verifyRelativeUriHandling(TestRestTemplate::delete);