Fixes #478 NPE when using scheme under securityScheme. (#479)

src/main/java/org/raml/parser/rule/SchemaRule.java

@@ -191,6 +191,7 @@ else if (node.getValue().matches("\\w.*"))
     private ScalarNode getGlobalSchemaNode(String key)
     {
         GlobalSchemasRule schemasRule = (GlobalSchemasRule) getRootTupleRule().getRuleByFieldName("schemas");
+        if (schemasRule == null) return null;
         return schemasRule.getSchema(key);
     }
 

src/test/java/org/raml/parser/builder/SecuritySchemaTestCase.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2016 (c) MuleSoft, Inc.
+ *
+ * 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.raml.parser.builder;
+
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.raml.model.Raml;
+import org.raml.parser.rule.ValidationResult;
+
+import java.util.List;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class SecuritySchemaTestCase extends AbstractRamlTestCase{
+
+  private static final String ramlSource = "org/raml/security-scheme-schema.yaml";
+  private static Raml raml;
+
+  @BeforeClass
+  public static void init()
+  {
+    raml = parseRaml(ramlSource);
+  }
+
+  @Test
+  public void build()
+  {
+    assertThat(raml.getSecuritySchemes().size(), is(1));
+  }
+
+  @Test
+  public void validate()
+  {
+    List<ValidationResult> errors = validateRaml(ramlSource);
+    Assert.assertTrue("Errors must be empty", errors.isEmpty());
+  }
+}

src/test/resources/org/raml/security-scheme-schema.yaml

@@ -0,0 +1,22 @@
+#%RAML 0.8
+title: test
+
+securitySchemes:
+  - x-token:
+      describedBy:
+        responses:
+          401:
+            body:
+              application/json:
+                schema: |
+                  {
+                    "type":"object",
+                    "$schema": "http://json-schema.org/draft-03/schema",
+                    "id":"http://jsonschema.net",
+                    "properties": {
+                      "message": {
+                        "required": true,
+                        "type": "string"
+                      }
+                    }
+                  }