Added field error code matching to MockMvc

This change adds a method within the ModelResultMatcher that will allow
a user to assert whether the returned Model has an attribute with a
field that has a specific error associated with it.

Issue: SPR-11971

spring-test/src/main/java/org/springframework/test/web/servlet/result/ModelResultMatchers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -160,13 +160,57 @@ public class ModelResultMatchers {
 				BindingResult result = getBindingResult(mav, name);
 				assertTrue("No errors for attribute: [" + name + "]", result.hasErrors());
 				for (final String fieldName : fieldNames) {
-					assertTrue("No errors for field: [" + fieldName + "] of attribute [" + name + "]",
-							result.hasFieldErrors(fieldName));
+					boolean hasFieldErrors = result.hasFieldErrors(fieldName);
+					assertTrue("No errors for field: [" + fieldName + "] of attribute [" + name + "]", hasFieldErrors);
 				}
 			}
 		};
 	}
 
+	/**
+	 * Assert a field error code for a model attribute using exact String match.
+	 * @since 4.1
+	 */
+	public ResultMatcher attributeHasFieldErrorCode(final String name, final String fieldName, final String error) {
+		return new ResultMatcher() {
+			public void match(MvcResult mvcResult) throws Exception {
+				ModelAndView mav = getModelAndView(mvcResult);
+				BindingResult result = getBindingResult(mav, name);
+				assertTrue("No errors for attribute: [" + name + "]", result.hasErrors());
+
+				boolean hasFieldErrors = result.hasFieldErrors(fieldName);
+				assertTrue("No errors for field: [" + fieldName + "] of attribute [" + name + "]", hasFieldErrors);
+
+				String code = result.getFieldError(fieldName).getCode();
+				assertTrue("Expected error code '" + error + "' but got '" + code + "'", code.equals(error));
+			}
+		};
+	}
+
+	/**
+	 * Assert a field error code for a model attribute using a {@link org.hamcrest.Matcher}.
+	 * @since 4.1
+	 */
+	public <T> ResultMatcher attributeHasFieldErrorCode(final String name, final String fieldName,
+			final Matcher<? super String> matcher) {
+
+		return new ResultMatcher() {
+			@Override
+			@SuppressWarnings("unchecked")
+			public void match(MvcResult mvcResult) throws Exception {
+				ModelAndView mav = getModelAndView(mvcResult);
+				BindingResult result = getBindingResult(mav, name);
+				assertTrue("No errors for attribute: [" + name + "]", result.hasErrors());
+
+				boolean hasFieldErrors = result.hasFieldErrors(fieldName);
+				assertTrue("No errors for field: [" + fieldName + "] of attribute [" + name + "]", hasFieldErrors);
+
+				String code = result.getFieldError(fieldName).getCode();
+				assertThat("Field name '" + fieldName + "' of attribute '" + name + "'", code, matcher);
+			}
+		};
+	}
+
 	/**
 	 * Assert the total number of errors in the model.
 	 */

spring-test/src/test/java/org/springframework/test/web/servlet/result/ModelResultMatchersTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -17,6 +17,7 @@
 package org.springframework.test.web.servlet.result;
 
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.startsWith;
 
 import java.util.Date;
 
@@ -24,12 +25,14 @@ import org.junit.Before;
 import org.junit.Test;
 import org.springframework.test.web.servlet.MvcResult;
 import org.springframework.test.web.servlet.StubMvcResult;
-import org.springframework.test.web.servlet.result.ModelResultMatchers;
 import org.springframework.validation.BeanPropertyBindingResult;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.servlet.ModelAndView;
 
 /**
+ * Unit tests for
+ * {@link org.springframework.test.web.servlet.result.ModelResultMatchers}.
+ *
  * @author Craig Walls
  */
 public class ModelResultMatchersTests {
@@ -145,6 +148,26 @@ public class ModelResultMatchersTests {
 		this.matchers.attributeHasFieldErrors("date", "good", "time").match(this.mvcResultWithError);
 	}
 
+	@Test
+	public void attributeHasFieldErrorCode() throws Exception {
+		this.matchers.attributeHasFieldErrorCode("date", "time", "error").match(this.mvcResultWithError);
+	}
+
+	@Test(expected = AssertionError.class)
+	public void attributeHasFieldErrorCode_withoutErrorOnField() throws Exception {
+		this.matchers.attributeHasFieldErrorCode("date", "time", "incorrectError").match(this.mvcResultWithError);
+	}
+
+	@Test
+	public void attributeHasFieldErrorCode_startsWith() throws Exception {
+		this.matchers.attributeHasFieldErrorCode("date", "time", startsWith("err")).match(this.mvcResultWithError);
+	}
+
+	@Test(expected = AssertionError.class)
+	public void attributeHasFieldErrorCode_startsWith_withoutErrorOnField() throws Exception {
+		this.matchers.attributeHasFieldErrorCode("date", "time", startsWith("inc")).match(this.mvcResultWithError);
+	}
+
 	private MvcResult getMvcResult(ModelAndView modelAndView) {
 		return new StubMvcResult(null, null, null, null, modelAndView, null, null);
 	}