Added piair's new StringBufferInstantiationWithChar rule, thanks piair!

git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@4788 51baf565-9d33-0410-a72c-fc3788e3496d

pmd/etc/changelog.txt

@@ -3,6 +3,7 @@ New rules:
     Basic ruleset: BigIntegerInstantiation(1.4 and 1.5)
     Codesize ruleset: NPathComplexity, NcssTypeCount, NcssMethodCount, NcssConstructorCount
     Design ruleset: UseCollectionIsEmpty
+    Strings ruleset: StringBufferInstantiationWithChar
     Typeresolution ruleset: Loose Coupling - This is a re-implementation using the new Type Resolution facility
 Fixed bug 1570915 - AvoidRethrowingException no longer reports a false positive for certain nested exceptions.
 Fixed bug 1571324 - UselessStringValueOf no longer reports a false positive for additive expressions.

pmd/regress/test/net/sourceforge/pmd/rules/strings/StringBufferInstantiationWithCharTest.java

@@ -0,0 +1,36 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+*/
+package test.net.sourceforge.pmd.rules.strings;
+
+import net.sourceforge.pmd.PMD;
+import net.sourceforge.pmd.Rule;
+import test.net.sourceforge.pmd.testframework.SimpleAggregatorTst;
+import test.net.sourceforge.pmd.testframework.TestDescriptor;
+
+public class StringBufferInstantiationWithCharTest extends SimpleAggregatorTst {
+
+    private Rule rule;
+
+    public void setUp() throws Exception {
+        rule = findRule("strings", "StringBufferInstantiationWithChar");
+    }
+
+    public void testAll() {
+        runTests(new TestDescriptor[] {
+                new TestDescriptor(TEST1, "OK", 0, rule),
+                new TestDescriptor(TEST2, "failure case", 1, rule),
+       });
+    }
+
+    private static final String TEST1 =
+        "public class Foo {" + PMD.EOL +
+        "  StringBuffer sb = new StringBuffer(\"c\");" + PMD.EOL +
+        "}";
+
+    private static final String TEST2 =
+        "public class Foo {" + PMD.EOL +
+        "  StringBuffer sb = new StringBuffer('c');" + PMD.EOL +
+        "}";
+
+}

pmd/regress/test/net/sourceforge/pmd/testframework/RuleTst.java

@@ -72,7 +72,7 @@ public class RuleTst extends TestCase {
     public void runTestFromString(TestDescriptor test,
                                   SourceType sourceType) throws Throwable {
         int res = processUsingStringReader(test.getCode(), test.getRule(), sourceType).size();
-        assertEquals("\"" + test.getDescription() + "\" test resulted in wrong amount of failures,",
+        assertEquals("\"" + test.getDescription() + "\" test resulted in wrong number of failures,",
             test.getNumberOfProblemsExpected(), res);
     }
 

pmd/rulesets/scratchpad.xml

@@ -10,9 +10,41 @@ These are new rules that are still in progress.
   </description>
 
 
-    <rule ref="rulesets/codesize.xml/CyclomaticComplexity">
-    </rule>
+    <rule   name="StringBufferInstantiationWithChar"
+            message="Do not instantiate a StringBuffer with a char"
+            class="net.sourceforge.pmd.rules.XPathRule"
+            externalInfoUrl="http://pmd.sourceforge.net/rules/strings.html#StringBufferInstantiationWithChar">
+        <description>
+    StringBuffer sb = new StringBuffer('c'); The
+    char will be converted into int to intialize
+    StringBuffer size.
+        </description>
+        <properties>
+            <property name="xpath">
+                <value>
+    <![CDATA[
+    //AllocationExpression/ClassOrInterfaceType
+    [@Image='StringBuffer']
+    /../Arguments/ArgumentList/Expression/PrimaryExpression
+    /PrimaryPrefix/
+    Literal [(starts-with(@Image, "'"))][(ends-with
+    (@Image, "'"))]
 
+    ]]>
+                </value>
+            </property>
+        </properties>
+        <priority>4</priority>
+        <example>
+    <![CDATA[
+    class Foo {
+      StringBuffer sb1 = new StringBuffer('c'); //Bad
+      StringBuffer sb2 = new StringBuffer("c"); //Better
+    }
+    ]]>
+        </example>
+        </rule>
+  
     <!--
     <rule name="UselessAssignment"
            message="This assignment to ''{0}'' is useless"

pmd/rulesets/strings.xml

@@ -288,5 +288,41 @@ public String convert(int i) {
           </example>
     </rule>
 
+
+<rule   name="StringBufferInstantiationWithChar"
+        message="Do not instantiate a StringBuffer with a char"
+        class="net.sourceforge.pmd.rules.XPathRule"
+        externalInfoUrl="http://pmd.sourceforge.net/rules/strings.html#StringBufferInstantiationWithChar">
+    <description>
+StringBuffer sb = new StringBuffer('c'); The
+char will be converted into int to intialize
+StringBuffer size.
+    </description>
+    <properties>
+        <property name="xpath">
+            <value>
+<![CDATA[
+//AllocationExpression/ClassOrInterfaceType
+[@Image='StringBuffer']
+/../Arguments/ArgumentList/Expression/PrimaryExpression
+/PrimaryPrefix/
+Literal [(starts-with(@Image, "'"))][(ends-with
+(@Image, "'"))]
+
+]]>
+            </value>
+        </property>
+    </properties>
+    <priority>4</priority>
+    <example>
+<![CDATA[
+class Foo {
+  StringBuffer sb1 = new StringBuffer('c'); //Bad
+  StringBuffer sb2 = new StringBuffer("c"); //Better
+}
+]]>
+    </example>
+    </rule>
+
 </ruleset>
 

pmd/xdocs/credits.xml

@@ -52,6 +52,7 @@
         </subsection>
         <subsection name="Contributors">
         <ul>
+            <li>piair - Implemented StringBufferInstantiationWithChar</li>
             <li>Christopher Eagan - Reported bug in VariableNamingConventions</li>
             <li>Jason Bennett - Noticed useless line in XSLT scripts, fix for UnnecessaryLocalBeforeReturn, wrote NPathComplexity rule, patches to improve CyclomaticComplexity rule, Implemented: UseCollectionIsEmpty, NcssTypeCount, NcssMethodCount, NcssConstructor</li>
             <li><a href="http://www.livejournal.com/users/insac/">Fabio Insaccanebbia</a> - Improvement for UseArraysAsList, UnusedNullCheckInEquals, MisplacedNullCheck, UselessOperationOnImmutable, AvoidArrayLoops, UseArraysAsList, AvoidConstantsInterface, AvoidDecimalLiteralsInBigDecimalConstructor, ClassCastExceptionWithToArray, BigIntegerInstantiation_1.4, BigIntegerInstantiation_1.5</li>