Include response body in UnknownHttpStatusCodeException

Spring Framework 5.2.2 introduced a regression in
DefaultResponseErrorHandler.handleError(ClientHttpResponse)
Specifically, for use cases where the InputStream had already been
consumed by the first invocation of getResponseBody(), the second
invocation of getResponseBody() resulted in the response body being
absent in the created UnknownHttpStatusCodeException.

This commit fixes this by invoking getResponseBody() only once in
DefaultResponseErrorHandler.handleError(ClientHttpReponse) in order to
reuse the retrieved response body for creating the exception message
and as a separate argument to the UnknownHttpStatusCodeException
constructor.

Closes gh-24595

spring-web/src/main/java/org/springframework/web/client/DefaultResponseErrorHandler.java

@@ -102,12 +102,13 @@ public class DefaultResponseErrorHandler implements ResponseErrorHandler {
 	public void handleError(ClientHttpResponse response) throws IOException {
 		HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
 		if (statusCode == null) {
+			byte[] body = getResponseBody(response);
 			String message = getErrorMessage(
 					response.getRawStatusCode(), response.getStatusText(),
-					getResponseBody(response), getCharset(response));
+					body, getCharset(response));
 			throw new UnknownHttpStatusCodeException(message,
 					response.getRawStatusCode(), response.getStatusText(),
-					response.getHeaders(), getResponseBody(response), getCharset(response));
+					response.getHeaders(), body, getCharset(response));
 		}
 		handleError(response, statusCode);
 	}

spring-web/src/test/java/org/springframework/web/client/DefaultResponseErrorHandlerTests.java

@@ -32,6 +32,7 @@ import org.springframework.util.StreamUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.catchThrowable;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
 
@@ -160,15 +161,29 @@ public class DefaultResponseErrorHandlerTests {
 
 	@Test
 	public void handleErrorForCustomClientError() throws Exception {
+		int statusCode = 499;
+		String statusText = "Custom status code";
+
 		HttpHeaders headers = new HttpHeaders();
 		headers.setContentType(MediaType.TEXT_PLAIN);
 
-		given(response.getRawStatusCode()).willReturn(499);
-		given(response.getStatusText()).willReturn("Custom status code");
+		String responseBody = "Hello World";
+		TestByteArrayInputStream body = new TestByteArrayInputStream(responseBody.getBytes(StandardCharsets.UTF_8));
+
+		given(response.getRawStatusCode()).willReturn(statusCode);
+		given(response.getStatusText()).willReturn(statusText);
 		given(response.getHeaders()).willReturn(headers);
+		given(response.getBody()).willReturn(body);
 
-		assertThatExceptionOfType(UnknownHttpStatusCodeException.class).isThrownBy(() ->
-				handler.handleError(response));
+		Throwable throwable = catchThrowable(() -> handler.handleError(response));
+
+		// validate exception
+		assertThat(throwable).isInstanceOf(UnknownHttpStatusCodeException.class);
+		UnknownHttpStatusCodeException actualUnknownHttpStatusCodeException = (UnknownHttpStatusCodeException) throwable;
+		assertThat(actualUnknownHttpStatusCodeException.getRawStatusCode()).isEqualTo(statusCode);
+		assertThat(actualUnknownHttpStatusCodeException.getStatusText()).isEqualTo(statusText);
+		assertThat(actualUnknownHttpStatusCodeException.getResponseHeaders()).isEqualTo(headers);
+		assertThat(actualUnknownHttpStatusCodeException.getResponseBodyAsString()).isEqualTo(responseBody);
 	}
 
 	@Test  // SPR-17461
@@ -185,15 +200,29 @@ public class DefaultResponseErrorHandlerTests {
 
 	@Test
 	public void handleErrorForCustomServerError() throws Exception {
+		int statusCode = 599;
+		String statusText = "Custom status code";
+
 		HttpHeaders headers = new HttpHeaders();
 		headers.setContentType(MediaType.TEXT_PLAIN);
 
-		given(response.getRawStatusCode()).willReturn(599);
-		given(response.getStatusText()).willReturn("Custom status code");
+		String responseBody = "Hello World";
+		TestByteArrayInputStream body = new TestByteArrayInputStream(responseBody.getBytes(StandardCharsets.UTF_8));
+
+		given(response.getRawStatusCode()).willReturn(statusCode);
+		given(response.getStatusText()).willReturn(statusText);
 		given(response.getHeaders()).willReturn(headers);
+		given(response.getBody()).willReturn(body);
 
-		assertThatExceptionOfType(UnknownHttpStatusCodeException.class).isThrownBy(() ->
-				handler.handleError(response));
+		Throwable throwable = catchThrowable(() -> handler.handleError(response));
+
+		// validate exception
+		assertThat(throwable).isInstanceOf(UnknownHttpStatusCodeException.class);
+		UnknownHttpStatusCodeException actualUnknownHttpStatusCodeException = (UnknownHttpStatusCodeException) throwable;
+		assertThat(actualUnknownHttpStatusCodeException.getRawStatusCode()).isEqualTo(statusCode);
+		assertThat(actualUnknownHttpStatusCodeException.getStatusText()).isEqualTo(statusText);
+		assertThat(actualUnknownHttpStatusCodeException.getResponseHeaders()).isEqualTo(headers);
+		assertThat(actualUnknownHttpStatusCodeException.getResponseBodyAsString()).isEqualTo(responseBody);
 	}
 
 	@Test  // SPR-16604
@@ -212,7 +241,6 @@ public class DefaultResponseErrorHandlerTests {
 		assertThat(StreamUtils.copyToString(response.getBody(), StandardCharsets.UTF_8)).isEqualTo("Hello World");
 	}
 
-
 	private static class TestByteArrayInputStream extends ByteArrayInputStream {
 
 		private boolean closed;