Fix NPE when non-default property null value is used

src/main/java/org/zalando/twintip/spring/SchemaResource.java

@@ -19,7 +19,6 @@
  * limitations under the License.
  * #L%
  */
-
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -36,6 +35,7 @@
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.util.StringUtils;
 
 import java.io.IOException;
 import java.net.URI;
@@ -55,9 +55,9 @@ public class SchemaResource {
 
     @Autowired
     public SchemaResource(
-            @Value("${twintip.yaml}") final Resource yamlResource,
-            @Value("${twintip.cors:true}") final boolean enableCors,
-            @Value("${twintip.baseUrl:}") final String baseUrl) throws IOException {
+        @Value("${twintip.yaml}") final Resource yamlResource,
+        @Value("${twintip.cors:true}") final boolean enableCors,
+        @Value("${twintip.baseUrl:}") final String baseUrl) throws IOException {
 
         this.json = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT);
         this.yaml = new ObjectMapper(new YAMLFactory());
@@ -66,30 +66,30 @@ public SchemaResource(
         });
         this.enableCors = enableCors;
 
-        if (!baseUrl.isEmpty()) {
+        if (!StringUtils.isEmpty(baseUrl)) {
             updateApiUrl(node, URI.create(baseUrl));
         }
     }
 
     @RequestMapping(method = RequestMethod.GET, value = SCHEMA_DISCOVERY_MAPPING,
-            produces = MediaType.APPLICATION_JSON_VALUE)
+        produces = MediaType.APPLICATION_JSON_VALUE)
     @ResponseStatus(HttpStatus.OK)
     public SchemaDiscovery discover(
-            @Value("${twintip.mapping}") final String mapping,
-            @Value("${twintip.type:swagger-2.0}") final String type,
-            @Value("${twintip.ui:}") final String uiPath) {
+        @Value("${twintip.mapping}") final String mapping,
+        @Value("${twintip.type:swagger-2.0}") final String type,
+        @Value("${twintip.ui:}") final String uiPath) {
         return new SchemaDiscovery(mapping, type, uiPath);
     }
 
     @RequestMapping(method = RequestMethod.GET, value = "${twintip.mapping}",
-            produces = {MediaType.APPLICATION_JSON_VALUE, MediaType.ALL_VALUE})
+        produces = {MediaType.APPLICATION_JSON_VALUE, MediaType.ALL_VALUE})
     @ResponseStatus(HttpStatus.OK)
     public ResponseEntity<String> jsonSchema() throws JsonProcessingException {
         return response(json.writeValueAsString(node));
     }
 
     @RequestMapping(method = RequestMethod.GET, value = "${twintip.mapping}",
-            produces = {"application/yaml", "application/x-yaml", "text/yaml"})
+        produces = {"application/yaml", "application/x-yaml", "text/yaml"})
     @ResponseStatus(HttpStatus.OK)
     @ResponseBody
     public ResponseEntity<String> yamlSchema() throws JsonProcessingException {
@@ -100,10 +100,10 @@ private ResponseEntity<String> response(final String body) {
         final ResponseEntity.BodyBuilder builder = ResponseEntity.ok();
         if (enableCors) {
             builder
-                    .header("Access-Control-Allow-Origin", "*")
-                    .header("Access-Control-Allow-Methods", "GET")
-                    .header("Access-Control-Max-Age", "3600")
-                    .header("Access-Control-Allow-Headers", "");
+                .header("Access-Control-Allow-Origin", "*")
+                .header("Access-Control-Allow-Methods", "GET")
+                .header("Access-Control-Max-Age", "3600")
+                .header("Access-Control-Allow-Headers", "");
         }
         return builder.body(body);
     }

src/test/java/org/zalando/twintip/spring/SchemaResourcePropertiesNullValueTest.java

@@ -0,0 +1,84 @@
+package org.zalando.twintip.spring;
+
+/*
+ * #%L
+ * twintip-spring-web
+ * %%
+ * Copyright (C) 2015 Zalando SE
+ * %%
+ * 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.
+ * #L%
+ */
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
+import org.springframework.http.HttpMethod;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+
+import static org.springframework.http.MediaType.APPLICATION_JSON;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.collection.IsCollectionWithSize.hasSize;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.request;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration
+@WebAppConfiguration
+@TestPropertySource(properties = {
+    "twintip.mapping=/api",
+    "twintip.yaml=classpath:/petstore.yml"
+})
+public class SchemaResourcePropertiesNullValueTest {
+
+    @Configuration
+    @EnableWebMvc
+    @Import(SchemaResource.class)
+    public static class TestConfiguration {
+
+        @Bean
+        public PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
+            final PropertySourcesPlaceholderConfigurer c = new PropertySourcesPlaceholderConfigurer();
+            c.setNullValue("");
+            return c;
+        }
+
+        @Bean
+        public MockMvc mvc(final WebApplicationContext context) {
+            return MockMvcBuilders.webAppContextSetup(context).build();
+        }
+    }
+
+    @Autowired
+    private MockMvc mvc;
+
+    @Test
+    public void apiDefaultBaseUrl() throws Exception {
+        mvc.perform(request(HttpMethod.GET, "/api"))
+            .andExpect(content().contentType(APPLICATION_JSON))
+            .andExpect(jsonPath("$.host", is("petstore.swagger.io")))
+            .andExpect(jsonPath("$.schemes", hasSize(1)));
+    }
+
+}