Add error stream tests for Jaxb2XmlDecoderTests

Issue: SPR-17418

spring-web/src/test/java/org/springframework/http/codec/xml/Jaxb2XmlDecoderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -38,9 +38,7 @@ import org.springframework.http.codec.xml.jaxb.XmlType;
 import org.springframework.http.codec.xml.jaxb.XmlTypeWithName;
 import org.springframework.http.codec.xml.jaxb.XmlTypeWithNameAndNamespace;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 /**
  * @author Sebastien Deleuze
@@ -207,6 +205,19 @@ public class Jaxb2XmlDecoderTests extends AbstractDataBufferAllocatingTestCase {
 				.verify();
 	}
 
+	@Test
+	public void decodeError() throws Exception {
+		Flux<DataBuffer> source = Flux.just(stringBuffer("<pojo>"))
+				.concatWith(Flux.error(new RuntimeException()));
+
+		Mono<Object> output = this.decoder.decodeToMono(source, ResolvableType.forClass(Pojo.class),
+				null, Collections.emptyMap());
+
+		StepVerifier.create(output)
+				.expectError(RuntimeException.class)
+				.verify();
+	}
+
 	@Test
 	public void toExpectedQName() {
 		assertEquals(new QName("pojo"), this.decoder.toQName(Pojo.class));