Implemented new rule InstantiationToGetClass, thanks Ernst!

git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@2837 51baf565-9d33-0410-a72c-fc3788e3496d

pmd/etc/changelog.txt

@@ -1,4 +1,5 @@
 ?????, 2004 - 2.0:
+New rules: InstantiationToGetClass
 Moved development environment to Maven 1.0.
 Moved development environment to Ant 1.6.2.  This is nice because using the new JUnit task attribute "forkmode='perBatch'" cuts test runtime from 90 seconds to 7 seconds.  Sweet.
 MethodWithSameNameAsEnclosingClass now reports a more helpful line number.

pmd/regress/test/net/sourceforge/pmd/rules/InstantiationToGetClassRuleTest.java

@@ -0,0 +1,39 @@
+package test.net.sourceforge.pmd.rules;
+
+import net.sourceforge.pmd.Rule;
+import net.sourceforge.pmd.RuleSetNotFoundException;
+import net.sourceforge.pmd.PMD;
+import test.net.sourceforge.pmd.testframework.TestDescriptor;
+import test.net.sourceforge.pmd.testframework.SimpleAggregatorTst;
+
+public class InstantiationToGetClassRuleTest extends SimpleAggregatorTst {
+
+    private Rule rule;
+
+    public void setUp() throws RuleSetNotFoundException {
+        rule = findRule("rulesets/newrules.xml", "InstantiationToGetClass");
+    }
+
+    public void testAll() {
+       runTests(new TestDescriptor[] {
+           new TestDescriptor(TEST1, "simple failure case", 1, rule),
+           new TestDescriptor(TEST2, "ok", 0, rule),
+           new TestDescriptor(TEST3, "should catch param to constructor", 1, rule),
+       });
+    }
+
+    private static final String TEST1 =
+    "public class Foo {" + PMD.EOL +
+    " Class clazz = new String().getClass();" + PMD.EOL +
+    "}";
+
+    private static final String TEST2 =
+    "public class Foo {" + PMD.EOL +
+    " Class clazz = getFoo().getClass();" + PMD.EOL +
+    "}";
+
+    private static final String TEST3 =
+    "public class Foo {" + PMD.EOL +
+    " Class clazz = new Integer(10).getClass();" + PMD.EOL +
+    "}";
+}

pmd/rulesets/newrules.xml

@@ -5,7 +5,35 @@
 These are new rules for the next release
   </description>
 
-
+    <rule name="InstantiationToGetClass"
+          message="Avoid instantiating an object just to call getClass() on it; use the .class public member instead"
+          class="net.sourceforge.pmd.rules.XPathRule">
+      <description>
+Avoid instantiating an object just to call getClass() on it; use the .class public member instead
+      </description>
+        <example>
+    <![CDATA[
+class Foo {
+ Class c = new String().getClass();
+}
+    ]]>
+        </example>
+        <priority>4</priority>
+        <properties>
+          <property name="xpath">
+            <value>
+                <![CDATA[
+//PrimarySuffix
+ [@Image='getClass']
+ [parent::PrimaryExpression
+  [PrimaryPrefix/AllocationExpression]
+  [count(PrimarySuffix) = 2]
+ ]
+     ]]>
+            </value>
+          </property>
+        </properties>
+      </rule>
 
 </ruleset>
 

pmd/rulesets/scratchpad.xml

@@ -5,21 +5,34 @@
 These are new rules that are still in progress
   </description>
 
-    <rule name="UnusedImports"
-          message="Avoid unused imports such as ''{0}''"
-          class="net.sourceforge.pmd.rules.UnusedImportsRule">
+    <rule name="InstantiationToGetClass"
+          message="Avoid instantiating an object just to call getClass() on it; use the .class public member instead"
+          class="net.sourceforge.pmd.rules.XPathRule">
       <description>
-      Avoid unused import statements.
+Avoid instantiating an object just to call getClass() on it; use the .class public member instead
       </description>
+        <example>
+    <![CDATA[
+class Foo {
+ Class c = new String().getClass();
+}
+    ]]>
+        </example>
         <priority>4</priority>
-
-      <example>
-  <![CDATA[
-  // this is bad
-  import java.io.File;
-  public class Foo {}
-  ]]>
-      </example>
+        <properties>
+          <property name="xpath">
+            <value>
+                <![CDATA[
+//PrimarySuffix
+ [@Image='getClass']
+ [parent::PrimaryExpression
+  [PrimaryPrefix/AllocationExpression]
+  [count(PrimarySuffix) = 2]
+ ]
+     ]]>
+            </value>
+          </property>
+        </properties>
       </rule>
 
 

pmd/xdocs/credits.xml

@@ -40,7 +40,7 @@
         </subsection>
         <subsection name="Contributors">
         <ul>
-            <li>Ernst Reissner - several rule suggestions, bug reports for UnusedPrivateField/CloseConnectionRule/ConstructorCallsOverridableMethodRule, and bug report and documentation suggestions for UseSingletonRule</li>
+            <li>Ernst Reissner - suggested InstantiationToGetClass, bug reports for UnusedPrivateField/CloseConnectionRule/ConstructorCallsOverridableMethodRule, and bug report and documentation suggestions for UseSingletonRule</li>
             <li>Philippe Couton - bug report for ExceptionAsFlowControl, OverrideBothEqualsAndHashcodeRule bug report, UseSingletonRule improvements, JUnitStaticSuiteRule improvements</li>
             <li>Dave Brosius - a couple of nice patches to clean up some string handling inefficiencies, non-static class usages, and unclosed streams/readers - found with Findbugs, I daresay :-)</li>
             <li>Paul Rowe - suggestion for improving MethodWithSameNameAsEnclosingClass, bug reports for SimplifyBooleanExpressions and UnusedLocalVariable</li>