pmd: fix #1121 NullPointerException when invoking XPathCLI

pmd/etc/changelog.txt

@@ -4,6 +4,7 @@ Fixed bug  881: private final without setter is flagged
 Fixed bug 1059: Change rule name "Use Singleton" should be "Use Utility class"
 Fixed bug 1106: PMD 5.0.4 fails with NPE on parsing java enum with inner class instance creation
 Fixed bug 1115: commentRequiredRule in pmd 5.1 is not working properly
+Fixed bug 1121: NullPointerException when invoking XPathCLI
 Fixed bug 1130: CloseResource doesn't recognize custom close method
 Fixed bug 1134: UseStringBufferLength: false positives
 Fixed bug 1136: ECMAScript: NullPointerException in getLeft() and getRight()

pmd/src/main/java/net/sourceforge/pmd/cli/XPathCLI.java

@@ -1,3 +1,6 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
 package net.sourceforge.pmd.cli;
 
 import java.io.File;
@@ -29,20 +32,29 @@ import net.sourceforge.pmd.util.StringUtil;
  */
 public class XPathCLI {
 
+    private static final Language LANGUAGE = Language.JAVA;
+
     public static void main(String[] args) throws Exception {
+        if (args.length != 4) {
+            System.err.println("Wrong arguments.\n");
+            System.err.println("Example:");
+            System.err.println("java " + XPathCLI.class.getName() + " -xpath \"//FieldDeclaration\" -filename \"/home/user/Test.java\"");
+            System.exit(1);
+        }
 
         String xpath = args[0].equals("-xpath") ? args[1] : args[3];
         String filename = args[0].equals("-file") ? args[1] : args[3];
         
         Rule rule = new XPathRule(xpath);
         rule.setMessage("Got one!");
+        rule.setLanguage(LANGUAGE);
         RuleSet ruleSet = RuleSet.createFor("", rule);
 
         RuleContext ctx = PMD.newRuleContext(filename, new File(filename));
-        ctx.setLanguageVersion(Language.JAVA.getDefaultVersion());
+        ctx.setLanguageVersion(LANGUAGE.getDefaultVersion());
 
         PMDConfiguration config = new PMDConfiguration();
-        config.setDefaultLanguageVersion(Language.JAVA.getDefaultVersion());
+        config.setDefaultLanguageVersion(LANGUAGE.getDefaultVersion());
         
         new SourceCodeProcessor(config).processSourceCode(new FileReader(filename), new RuleSets(ruleSet), ctx);
 

pmd/src/test/java/net/sourceforge/pmd/cli/XPathCLITest.java

@@ -0,0 +1,35 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+package net.sourceforge.pmd.cli;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+
+import junit.framework.Assert;
+
+import org.junit.Test;
+
+public class XPathCLITest {
+
+    @Test
+    public void runXPath() throws Exception {
+        PrintStream oldOut = System.out;
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+        System.setOut(new PrintStream(output));
+
+        try {
+            XPathCLI.main(new String[] {
+                    "-xpath",
+                    "//ClassOrInterfaceDeclaration",
+                    "-filename",
+                    "src/test/java/net/sourceforge/pmd/cli/XPathCLITest.java"
+            });
+            System.out.flush();
+        } finally {
+            System.setOut(oldOut);
+        }
+
+        Assert.assertTrue(output.toString("UTF-8").startsWith("Match at line "));
+    }
+}