Use custom validator on supported classes only

Previously, a customer was set regardless of the fact that it is
supported on the target bean. DataBinder has an actual assertion check
that would fail in such a case.

We now associate the custom validator only if it supports the target
bean.

Fixes gh-3581

spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -66,6 +66,7 @@ import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
  * @author Dave Syer
  * @author Phillip Webb
  * @author Christian Dupuis
+ * @author Stephane Nicoll
  */
 public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProcessor,
 		BeanFactoryAware, ResourceLoaderAware, EnvironmentAware, ApplicationContextAware,
@@ -321,13 +322,15 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 	}
 
 	private Validator determineValidator(Object bean) {
+		boolean globalValidatorSupportBean = (this.validator != null
+				&& this.validator.supports(bean.getClass()));
 		if (ClassUtils.isAssignable(Validator.class, bean.getClass())) {
-			if (this.validator == null) {
+			if (!globalValidatorSupportBean) {
 				return (Validator) bean;
 			}
 			return new ChainingValidator(this.validator, (Validator) bean);
 		}
-		return this.validator;
+		return globalValidatorSupportBean ? this.validator : null;
 	}
 
 	private PropertySources loadPropertySources(String[] locations,

spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessorTests.java

@@ -54,6 +54,7 @@ import static org.junit.Assert.fail;
  *
  * @author Christian Dupuis
  * @author Phillip Webb
+ * @author Stephane Nicoll
  */
 public class ConfigurationPropertiesBindingPostProcessorTests {
 
@@ -133,6 +134,39 @@ public class ConfigurationPropertiesBindingPostProcessorTests {
 		this.context.refresh();
 	}
 
+	@Test
+	public void testValidationWithCustomValidator() {
+		this.context = new AnnotationConfigApplicationContext();
+		this.context.register(TestConfigurationWithCustomValidator.class);
+		try {
+			this.context.refresh();
+			fail("Expected exception");
+		}
+		catch (BeanCreationException ex) {
+			BindException bex = (BindException) ex.getRootCause();
+			assertEquals(1, bex.getErrorCount());
+		}
+	}
+
+	@Test
+	public void testValidationWithCustomValidatorNotSupported() {
+		MockEnvironment env = new MockEnvironment();
+		env.setProperty("test.foo", "bar");
+		this.context = new AnnotationConfigApplicationContext();
+		this.context.setEnvironment(env);
+		this.context.register(TestConfigurationWithCustomValidator.class,
+				PropertyWithValidatingSetter.class);
+		try {
+			// PropertyWithValidatingSetter should not use validator
+			this.context.refresh();
+			fail("Expected exception");
+		}
+		catch (BeanCreationException ex) {
+			BindException bex = (BindException) ex.getRootCause();
+			assertEquals(1, bex.getErrorCount());
+		}
+	}
+
 	@Test
 	public void testPropertyWithEnum() throws Exception {
 		doEnumTest("test.theValue:foo");
@@ -373,6 +407,50 @@ public class ConfigurationPropertiesBindingPostProcessorTests {
 
 	}
 
+	@Configuration
+	@EnableConfigurationProperties
+	public static class TestConfigurationWithCustomValidator {
+
+		@Bean
+		public PropertyWithCustomValidator propertyWithCustomValidator() {
+			return new PropertyWithCustomValidator();
+		}
+
+		@Bean
+		public Validator configurationPropertiesValidator() {
+			return new CustomPropertyValidator();
+		}
+
+	}
+
+	@ConfigurationProperties(prefix = "custom")
+	public static class PropertyWithCustomValidator {
+
+		private String foo;
+
+		public String getFoo() {
+			return foo;
+		}
+
+		public void setFoo(String foo) {
+			this.foo = foo;
+		}
+	}
+
+	public static class CustomPropertyValidator implements Validator {
+
+		@Override
+		public boolean supports(Class<?> aClass) {
+			return aClass == PropertyWithCustomValidator.class;
+		}
+
+		@Override
+		public void validate(Object o, Errors errors) {
+			ValidationUtils.rejectIfEmpty(errors, "foo", "TEST1");
+		}
+
+	}
+
 	@Configuration
 	@EnableConfigurationProperties
 	@ConfigurationProperties(prefix = "test", ignoreUnknownFields = false)