Add configuration properties validation sample

Create a new project sample that demonstrate the usage of
@ConfigurationProperties with configurationPropertiesValidator.

Fixes gh-3513

spring-boot-samples/spring-boot-sample-property-validation/src/test/java/sample/propertyvalidation/SamplePropertyValidationApplicationTests.java

@@ -0,0 +1,85 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://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 sample.propertyvalidation;
+
+import org.junit.Test;
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.test.EnvironmentTestUtils;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.validation.Validator;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Tests for {@link SamplePropertyValidationApplication}.
+ *
+ * @author Lucas Saldanha
+ */
+public class SamplePropertyValidationApplicationTests {
+
+	private final AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+
+	@Test
+	public void testBindingValidProperties() {
+		this.context.register(TestConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context, "host:192.168.0.1");
+		EnvironmentTestUtils.addEnvironment(this.context, "port:8080");
+		this.context.refresh();
+
+		assertEquals(1, this.context.getBeanNamesForType(SampleProperties.class).length);
+		SampleProperties properties = this.context.getBean(SampleProperties.class);
+		assertEquals("192.168.0.1", properties.getHost());
+		assertEquals(8080, (int) properties.getPort());
+	}
+
+	@Test(expected = BeanCreationException.class)
+	public void testBindingInvalidProperties() {
+		this.context.register(TestConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context, "host:xxxxxx");
+		EnvironmentTestUtils.addEnvironment(this.context, "port:8080");
+		this.context.refresh();
+	}
+
+	@Test
+	public void testBindingValidPropertiesWithMultipleConfigurationPropertiesClasses() {
+		this.context.register(TestConfiguration.class);
+		this.context.register(ServerProperties.class);
+		EnvironmentTestUtils.addEnvironment(this.context, "host:192.168.0.1");
+		EnvironmentTestUtils.addEnvironment(this.context, "port:8080");
+		this.context.refresh();
+
+		assertEquals(1, this.context.getBeanNamesForType(SampleProperties.class).length);
+		SampleProperties properties = this.context.getBean(SampleProperties.class);
+		assertEquals("192.168.0.1", properties.getHost());
+		assertEquals(8080, (int) properties.getPort());
+	}
+
+	@Configuration
+	@EnableConfigurationProperties(SampleProperties.class)
+	protected static class TestConfiguration {
+
+		@Bean
+		public Validator configurationPropertiesValidator() {
+			return new ConfigurationPropertiesValidator();
+		}
+	}
+
+}