Add default value (and log warning) if applicationId is null

Fixes gh-86

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/archaius/ArchaiusAutoConfiguration.java

@@ -55,7 +55,8 @@ public class ArchaiusAutoConfiguration {
         if (initialized.compareAndSet(false, true)) {
             String appName = env.getProperty("spring.application.name");
             if (appName == null) {
-                throw new IllegalStateException("spring.application.name may not be null");
+                appName = "application";
+                logger.warn("No spring.application.name found, defaulting to 'application'");
             }
             //this is deprecated, but currently it seams the only way to set it initially
             System.setProperty(DEPLOYMENT_APPLICATION_ID_PROPERTY, appName);

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/archaius/ArchaiusAutoConfigurationTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2013-2014 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.
+ * 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 org.springframework.cloud.netflix.archaius;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.apache.commons.configuration.AbstractConfiguration;
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class ArchaiusAutoConfigurationTests {
+
+	private AnnotationConfigApplicationContext context;
+	
+	@After
+	public void close() {
+		if (context!=null) {
+			context.close();
+		}
+	}
+
+	@Test
+	public void configurationCreated() {
+		context = new AnnotationConfigApplicationContext(ArchaiusAutoConfiguration.class);
+		AbstractConfiguration config = context.getBean(ConfigurableEnvironmentConfiguration.class);
+		assertNotNull(config.getString("java.io.tmpdir"));
+	}
+
+}