Exception response for MockRestServiceServer

Closes gh-1954

spring-test/src/main/java/org/springframework/test/web/client/response/MockRestResponseCreators.java

@@ -16,6 +16,7 @@
 
 package org.springframework.test.web.client.response;
 
+import java.io.IOException;
 import java.net.URI;
 
 import org.springframework.core.io.Resource;
@@ -116,4 +117,15 @@ public abstract class MockRestResponseCreators {
 		return new DefaultResponseCreator(status);
 	}
 
+	/**
+	 * {@code ResponseCreator} with an internal application {@code IOException}. For example,
+	 * one could use this to simulate a {@code SocketTimeoutException}.
+	 * @param e the {@code Exception} to be thrown at HTTP call time.
+	 */
+	public static ResponseCreator withException(IOException e) {
+		return request -> {
+			throw e;
+		};
+	}
+
 }

spring-test/src/test/java/org/springframework/test/web/client/response/ResponseCreatorsTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.test.web.client.response;
 
+import java.net.SocketTimeoutException;
 import java.net.URI;
 
 import org.junit.jupiter.api.Test;
@@ -23,6 +24,7 @@ import org.junit.jupiter.api.Test;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.mock.http.client.MockClientHttpResponse;
+import org.springframework.test.web.client.ResponseCreator;
 import org.springframework.util.StreamUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -124,4 +126,10 @@ public class ResponseCreatorsTests {
 		assertThat(StreamUtils.copyToByteArray(response.getBody()).length).isEqualTo(0);
 	}
 
+	@Test(expected = SocketTimeoutException.class)
+	public void withException() throws Exception {
+		ResponseCreator responseCreator = MockRestResponseCreators.withException(new SocketTimeoutException());
+		responseCreator.createResponse(null);
+	}
+
 }