Preserve response body on errors when using ReactiveCredHubTemplate

Resolves #69

Signed-off-by: Roy Clarkson <roy.clarkson@broadcom.com>

Author: royclarkson

spring-credhub-core/src/main/java/org/springframework/credhub/core/CredHubException.java

@@ -16,6 +16,7 @@
 
 package org.springframework.credhub.core;
 
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.web.client.HttpStatusCodeException;
 
@@ -45,4 +46,15 @@ public CredHubException(HttpStatusCode statusCode) {
 		super(statusCode);
 	}
 
+	/**
+	 * Create a new exception with the provided error status code, headers, and response
+	 * body.
+	 * @param statusCode an {@link HttpStatusCode} indicating an error
+	 * @param headers the response headers
+	 * @param responseBody the response body as a byte array
+	 */
+	public CredHubException(HttpStatusCode statusCode, HttpHeaders headers, byte[] responseBody) {
+		super(statusCode, statusCode.toString(), headers, responseBody, null);
+	}
+
 }

spring-credhub-core/src/main/java/org/springframework/credhub/core/ExceptionUtils.java

@@ -52,7 +52,9 @@ public static void throwExceptionOnError(ResponseEntity<?> response) {
 	 * @return the generated error
 	 */
 	public static Mono<Throwable> buildError(ClientResponse response) {
-		return Mono.error(new CredHubException(response.statusCode()));
+		return response.bodyToMono(byte[].class)
+			.defaultIfEmpty(new byte[0])
+			.map((body) -> new CredHubException(response.statusCode(), response.headers().asHttpHeaders(), body));
 	}
 
 }

spring-credhub-core/src/test/java/org/springframework/credhub/core/ExceptionUtilsUnitTests.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2016-2020 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
+ *
+ *      https://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.credhub.core;
+
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.reactive.function.client.ClientResponse;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+class ExceptionUtilsUnitTests {
+
+	@Test
+	void throwExceptionOnErrorPreservesStatusCode() {
+		ResponseEntity<String> response = ResponseEntity.status(HttpStatus.FORBIDDEN).body("access denied");
+
+		assertThatExceptionOfType(CredHubException.class)
+			.isThrownBy(() -> ExceptionUtils.throwExceptionOnError(response))
+			.satisfies((ex) -> assertThat(ex.getStatusCode()).isEqualTo(HttpStatus.FORBIDDEN));
+	}
+
+	@Test
+	void throwExceptionOnErrorDoesNothingForOk() {
+		ResponseEntity<String> response = ResponseEntity.ok("success");
+
+		ExceptionUtils.throwExceptionOnError(response);
+	}
+
+	@Test
+	void buildErrorPreservesStatusCodeAndResponseBody() {
+		ClientResponse clientResponse = ClientResponse.create(HttpStatus.FORBIDDEN)
+			.body("{\"error\":\"access denied\"}")
+			.build();
+
+		Mono<Throwable> error = ExceptionUtils.buildError(clientResponse);
+
+		StepVerifier.create(error).assertNext((ex) -> {
+			assertThat(ex).isInstanceOf(CredHubException.class);
+			CredHubException credHubException = (CredHubException) ex;
+			assertThat(credHubException.getStatusCode()).isEqualTo(HttpStatus.FORBIDDEN);
+			assertThat(credHubException.getResponseBodyAsString()).isEqualTo("{\"error\":\"access denied\"}");
+		}).verifyComplete();
+	}
+
+	@Test
+	void buildErrorHandlesEmptyBody() {
+		ClientResponse clientResponse = ClientResponse.create(HttpStatus.INTERNAL_SERVER_ERROR).build();
+
+		Mono<Throwable> error = ExceptionUtils.buildError(clientResponse);
+
+		StepVerifier.create(error).assertNext((ex) -> {
+			assertThat(ex).isInstanceOf(CredHubException.class);
+			CredHubException credHubException = (CredHubException) ex;
+			assertThat(credHubException.getStatusCode()).isEqualTo(HttpStatus.INTERNAL_SERVER_ERROR);
+			assertThat(credHubException.getResponseBodyAsString()).isEmpty();
+		}).verifyComplete();
+	}
+
+}