From 751ed84e0d9d63aeb379284d1052de92ce171221 Mon Sep 17 00:00:00 2001
From: Xavier Le Vourch <xlv@users.sourceforge.net>
Date: Thu, 5 Feb 2009 03:29:15 +0000
Subject: [PATCH] new rule in strictexception:
 AvoidThrowingNewInstanceOfSameException

contributed by George Thomas:

https://sourceforge.net/tracker/?func=detail&amp;atid=479923&amp;aid=2566369&amp;group_id=56262


git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/branches/pmd/4.2.x@6814 51baf565-9d33-0410-a72c-fc3788e3496d
---
 pmd/etc/changelog.txt                         |   3 +
 .../StrictExceptionRulesTest.java             |   1 +
 ...voidThrowingNewInstanceOfSameException.xml | 139 ++++++++++++++++++
 pmd/rulesets/strictexception.xml              |  43 +++++-
 4 files changed, 185 insertions(+), 1 deletion(-)
 create mode 100644 pmd/regress/test/net/sourceforge/pmd/rules/strictexception/xml/AvoidThrowingNewInstanceOfSameException.xml

diff --git a/pmd/etc/changelog.txt b/pmd/etc/changelog.txt
index 0fbbf7579a..38886976fe 100644
--- a/pmd/etc/changelog.txt
+++ b/pmd/etc/changelog.txt
@@ -10,6 +10,9 @@ Fixed bug 2404700 - UseSingleton should not act on enums
 Fixed bug 2225474 - VariableNamingConventions does not work with nonprimitives
 Fixed bug - JUnitTestsShouldIncludeAssert now detects Junit 4 Assert.assert...  constructs
 
+New rule:
+	StrictExceptions : AvoidThrowingNewInstanceOfSameException
+
 October 12, 2008 - 4.2.4:
 
 Fixed bug 1481051 - false + UnusedNullCheckInEquals (and other false positives too)
diff --git a/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/StrictExceptionRulesTest.java b/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/StrictExceptionRulesTest.java
index 99a96c2385..bcca57f0bd 100644
--- a/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/StrictExceptionRulesTest.java
+++ b/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/StrictExceptionRulesTest.java
@@ -11,6 +11,7 @@ public class StrictExceptionRulesTest extends SimpleAggregatorTst {
         addRule("strictexception", "AvoidCatchingNPE");
         addRule("strictexception", "AvoidCatchingThrowable");
         addRule("strictexception", "AvoidRethrowingException");
+        addRule("strictexception", "AvoidThrowingNewInstanceOfSameException");
         addRule("strictexception", "AvoidThrowingNullPointerException");
         addRule("strictexception", "AvoidThrowingRawExceptionTypes");
         addRule("strictexception", "DoNotExtendJavaLangError");
diff --git a/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/xml/AvoidThrowingNewInstanceOfSameException.xml b/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/xml/AvoidThrowingNewInstanceOfSameException.xml
new file mode 100644
index 0000000000..05b9bf162e
--- /dev/null
+++ b/pmd/regress/test/net/sourceforge/pmd/rules/strictexception/xml/AvoidThrowingNewInstanceOfSameException.xml
@@ -0,0 +1,139 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<test-data>
+	<test-code>
+		<description><![CDATA[
+basic failure case
+     ]]></description>
+		<expected-problems>1</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    throw new SomeException(se);
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+do something else before throwing a new instance of the same exception, ok
+     ]]></description>
+		<expected-problems>0</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    System.out.println("something interesting");
+    throw new SomeException(se);
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+repackage cause as an instance of the same exception, failure
+     ]]></description>
+		<expected-problems>1</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    throw new SomeException(se.getCause());
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+throw new instance of the same exception with a different message, ok
+     ]]></description>
+		<expected-problems>0</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    throw new SomeException("new exception message", se);
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+throw new instance of the same exception with the same message, failure
+     ]]></description>
+		<expected-problems>1</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    throw new SomeException(se.getMessage());
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+throws a new instance of the same exception without any arguments, ok
+     ]]></description>
+		<expected-problems>0</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+   try {
+   } catch (SomeException se) {
+    throw new SomeException();
+   }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+throws a new instance of the same exception from a nested try/catch block, ok
+     ]]></description>
+		<expected-problems>0</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+    try {
+    } catch (SomeException se) {
+      try {
+      } catch (OtherException oe) {
+         throw new SomeException();
+      }
+    }
+  }
+}
+     ]]></code>
+	</test-code>
+	<test-code>
+		<description><![CDATA[
+wraps the exception in a new instance of the same exception from a nested try/catch block, ok
+     ]]></description>
+		<expected-problems>0</expected-problems>
+		<code><![CDATA[
+public class Foo {
+  void bar() {
+    try {
+    } catch (SomeException se) {
+      try {
+      } catch (OtherException oe) {
+         throw new SomeException(se);
+      }
+    }
+  }
+}
+     ]]></code>
+	</test-code>
+</test-data>
+
diff --git a/pmd/rulesets/strictexception.xml b/pmd/rulesets/strictexception.xml
index e4a2b8b188..bdd0a772c9 100644
--- a/pmd/rulesets/strictexception.xml
+++ b/pmd/rulesets/strictexception.xml
@@ -287,7 +287,48 @@ public class Foo {
 				}
 	    	]]>
     	</example>
-	</rule>
+    </rule>
 
+  <rule name="AvoidThrowingNewInstanceOfSameException"
+    since="4.2.5"
+    message="A catch statement that catches an exception only to wrap it in a new instance of the same type of exception and throw it should be avoided"
+    externalInfoUrl="http://pmd.sourceforge.net/rules/strictexception.html#AvoidThrowingNewInstanceOfSameException"
+    class="net.sourceforge.pmd.rules.XPathRule">
+    <description>
+     Catch blocks that merely rethrow a caught exception wrapped inside a new instance of the same type only add to code size and runtime complexity.
+    </description>
+    <priority>3</priority>
+    <properties>
+    <property name="xpath">
+      <value>
+        <![CDATA[
+//CatchStatement[
+  count(Block/BlockStatement/Statement) = 1
+  and
+  FormalParameter/Type/ReferenceType/ClassOrInterfaceType/@Image = Block/BlockStatement/Statement/ThrowStatement/Expression/PrimaryExpression/PrimaryPrefix/AllocationExpression/ClassOrInterfaceType/@Image
+  and
+  count(Block/BlockStatement/Statement/ThrowStatement/Expression/PrimaryExpression/PrimaryPrefix/AllocationExpression/Arguments/ArgumentList/Expression) = 1
+  and
+  FormalParameter/VariableDeclaratorId = Block/BlockStatement/Statement/ThrowStatement/Expression/PrimaryExpression/PrimaryPrefix/AllocationExpression/Arguments/ArgumentList/Expression/PrimaryExpression/PrimaryPrefix/Name
+  ]
+ ]]>
+      </value>
+    </property>
+    </properties>    
+    <example>  <![CDATA[
+    public class Foo {
+     void bar() {
+      try {
+       // do something
+      }  catch (SomeException se) {
+         // harmless comment      
+           throw new SomeException(se);
+      }
+     }
+    }
+  ]]>
+    </example>
+  </rule>
 
 </ruleset>
+