Add accept(String) method to mock request builder

Issue: SPR-10390

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilder.java

@@ -25,6 +25,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
+
 import javax.servlet.ServletContext;
 import javax.servlet.ServletRequest;
 import javax.servlet.http.Cookie;
@@ -188,6 +189,21 @@ public class MockHttpServletRequestBuilder implements RequestBuilder, Mergeable
 		return this;
 	}
 
+	/**
+	 * Set the 'Accept' header to the given media type(s).
+	 *
+	 * @param mediaTypes one or more media types
+	 */
+	public MockHttpServletRequestBuilder accept(String... mediaTypes) {
+		Assert.notEmpty(mediaTypes, "No 'Accept' media types");
+		List<MediaType> result = new ArrayList<MediaType>(mediaTypes.length);
+		for (String mediaType : mediaTypes) {
+			result.add(MediaType.parseMediaType(mediaType));
+		}
+		this.headers.set("Accept", MediaType.toString(result));
+		return this;
+	}
+
 	/**
 	 * Set the request body.
 	 *