Initial stubs for Psi checker and tests for it

idea/META-INF/plugin.xml

@@ -22,5 +22,6 @@
       <lang.parserDefinition language="jet" implementationClass="org.jetbrains.jet.lang.parsing.JetParserDefinition"/>
       <lang.commenter language="jet" implementationClass="org.jetbrains.jet.plugin.JetCommenter"/>
       <annotator language="jet" implementationClass="org.jetbrains.jet.lang.annotations.SoftKeywordsAnnotator"/>
+      <annotator language="jet" implementationClass="org.jetbrains.jet.lang.annotations.JetPsiChecker"/>
   </extensions>
 </idea-plugin>

idea/src/org/jetbrains/jet/lang/annotations/JetPsiChecker.java

@@ -0,0 +1,21 @@
+package org.jetbrains.jet.lang.annotations;
+
+import com.intellij.lang.annotation.AnnotationHolder;
+import com.intellij.lang.annotation.Annotator;
+import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.psi.JetProperty;
+
+/**
+ * @author abreslav
+ */
+public class JetPsiChecker implements Annotator {
+
+    @Override
+    public void annotate(@NotNull PsiElement element, @NotNull AnnotationHolder holder) {
+        if (element instanceof JetProperty) {
+            JetProperty property = (JetProperty) element;
+            holder.createErrorAnnotation(property.getNameIdentifier(), "Specify either type or value");
+        }
+    }
+}

idea/testData/checker/Properties.jet

@@ -0,0 +1,2 @@
+val <error descr="Specify either type or value">foo</error>
+

idea/tests/org/jetbrains/jet/parsing/JetPsiCheckerTest.java

@@ -0,0 +1,25 @@
+package org.jetbrains.jet.parsing;
+
+import com.intellij.codeInsight.daemon.LightDaemonAnalyzerTestCase;
+import com.intellij.openapi.application.PathManager;
+
+import java.io.File;
+
+/**
+ * @author abreslav
+ */
+public class JetPsiCheckerTest extends LightDaemonAnalyzerTestCase {
+
+    @Override
+    protected String getTestDataPath() {
+        return getHomeDirectory() + "/idea/testData";
+    }
+
+    private static String getHomeDirectory() {
+       return new File(PathManager.getResourceRoot(JetParsingTest.class, "/org/jetbrains/jet/parsing/JetParsingTest.class")).getParentFile().getParentFile().getParent();
+    }
+
+    public void testFoo() throws Exception {
+        doTest("/checker/Properties.jet", true, true);
+    }
+}