Throw an exception if a config file that exists cannot be parsed

Fixes gh-209 in a general way

spring-boot/src/main/java/org/springframework/boot/context/listener/ConfigFileApplicationListener.java

@@ -104,6 +104,8 @@ public class ConfigFileApplicationListener implements
 
 	private PropertySourceAnnotations propertySourceAnnotations = new PropertySourceAnnotations();
 
+	private PropertySourceLoaderFactory propertySourceLoaderFactory = new DefaultPropertySourceLoaderFactory();
+
 	/**
 	 * Binds the early {@link Environment} to the {@link SpringApplication}. This makes it
 	 * possible to set {@link SpringApplication} properties dynamically, like the sources
@@ -284,12 +286,8 @@ public class ConfigFileApplicationListener implements
 			return null;
 		}
 
-		List<PropertySourceLoader> loaders = new ArrayList<PropertySourceLoader>();
-		loaders.add(new PropertiesPropertySourceLoader());
-		if (ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", null)) {
-			loaders.add(YamlPropertySourceLoader.springProfileAwareLoader(environment
-					.getActiveProfiles()));
-		}
+		List<PropertySourceLoader> loaders = this.propertySourceLoaderFactory
+				.getLoaders(environment);
 
 		Resource resource = resourceLoader.getResource(location);
 		String name = this.propertySourceAnnotations.name(location);
@@ -334,12 +332,22 @@ public class ConfigFileApplicationListener implements
 		if (this.cached.containsKey(key)) {
 			return this.cached.get(key);
 		}
+		boolean satisfied = true;
 		for (PropertySourceLoader loader : loaders) {
-			if (resource != null && resource.exists() && loader.supports(resource)) {
+			if (resource != null && resource.exists()) {
+				if (loader.supports(resource)) {
 					PropertySource<?> propertySource = loader.load(name, resource);
 					this.cached.put(key, propertySource);
 					return propertySource;
 				}
+				else {
+					satisfied = false;
+				}
+			}
+		}
+		if (!satisfied) {
+			throw new IllegalStateException(
+					"No supported loader found for configuration resource: " + resource);
 		}
 		return null;
 	}
@@ -368,6 +376,14 @@ public class ConfigFileApplicationListener implements
 		this.searchLocations = (searchLocations == null ? null : searchLocations.clone());
 	}
 
+	/**
+	 * @param propertySourceLoaderFactory the factory to set
+	 */
+	public void setPropertySourceLoaderFactory(
+			PropertySourceLoaderFactory propertySourceLoaderFactory) {
+		this.propertySourceLoaderFactory = propertySourceLoaderFactory;
+	}
+
 	private static class RandomValuePropertySource extends PropertySource<Random> {
 
 		public RandomValuePropertySource(String name) {
@@ -444,4 +460,24 @@ public class ConfigFileApplicationListener implements
 		}
 	}
 
+	public static interface PropertySourceLoaderFactory {
+		List<PropertySourceLoader> getLoaders(Environment environment);
+	}
+
+	private static class DefaultPropertySourceLoaderFactory implements
+			PropertySourceLoaderFactory {
+
+		@Override
+		public List<PropertySourceLoader> getLoaders(Environment environment) {
+			ArrayList<PropertySourceLoader> loaders = new ArrayList<PropertySourceLoader>();
+			loaders.add(new PropertiesPropertySourceLoader());
+			if (ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", null)) {
+				loaders.add(YamlPropertySourceLoader.springProfileAwareLoader(environment
+						.getActiveProfiles()));
+			}
+			return loaders;
+		}
+
+	}
+
 }

spring-boot/src/test/java/org/springframework/boot/context/listener/ConfigFileApplicationListenerTests.java

@@ -18,20 +18,27 @@ package org.springframework.boot.context.listener;
 
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.junit.After;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.SpringApplicationEnvironmentAvailableEvent;
+import org.springframework.boot.config.PropertySourceLoader;
+import org.springframework.boot.context.listener.ConfigFileApplicationListener.PropertySourceLoaderFactory;
 import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Profile;
 import org.springframework.context.annotation.PropertySource;
+import org.springframework.core.env.Environment;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.SimpleCommandLinePropertySource;
 import org.springframework.core.env.StandardEnvironment;
+import org.springframework.core.io.Resource;
 
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.equalTo;
@@ -57,6 +64,9 @@ public class ConfigFileApplicationListenerTests {
 
 	private ConfigFileApplicationListener initializer = new ConfigFileApplicationListener();
 
+	@Rule
+	public ExpectedException expected = ExpectedException.none();
+
 	@After
 	public void cleanup() {
 		System.clearProperty("my.property");
@@ -198,6 +208,34 @@ public class ConfigFileApplicationListenerTests {
 		assertThat(this.environment.getPropertySources().contains(location), is(true));
 	}
 
+	@Test
+	public void unsupportedResource() throws Exception {
+		this.initializer
+				.setPropertySourceLoaderFactory(new PropertySourceLoaderFactory() {
+					@Override
+					public List<PropertySourceLoader> getLoaders(Environment environment) {
+						return Arrays
+								.<PropertySourceLoader> asList(new PropertySourceLoader() {
+
+									@Override
+									public boolean supports(Resource resource) {
+										return false;
+									}
+
+									@Override
+									public org.springframework.core.env.PropertySource<?> load(
+											String name, Resource resource) {
+										return null;
+									}
+
+								});
+					}
+				});
+		this.expected.expect(IllegalStateException.class);
+		this.expected.expectMessage("No supported loader");
+		this.initializer.onApplicationEvent(this.event);
+	}
+
 	@Test
 	public void specificResourceDefaultsToFile() throws Exception {
 		String location = "src/test/resources/specificlocation.properties";