ruleset: MoveVariableInsideIf: enabled for 4-tweaks and above

README.md

@@ -181,6 +181,7 @@ Rule|Level|Source|Enabled|Suppressible
 [MissingSwitchDefault](#missingswitchdefault)|tweaks|checkstyle|Yes|
 [ModifiedControlVariable](#modifiedcontrolvariable)|tweaks|checkstyle|Yes|
 [ModifierOrder](#modifierorder)|naming|checkstyle|Yes|
+[MoveVariableInsideIfCheck](#movevariableinsideifcheck)|tweaks|sevntu|Yes|
 [MultipleStringLiterals](#multiplestringliterals)|naming|checkstyle|Yes|
 [MultipleVariableDeclarations](#multiplevariabledeclarations)|naming|checkstyle|Yes|
 [MutableException](#mutableexception)|tweaks|checkstyle|Yes|
@@ -2333,6 +2334,29 @@ if (getProperty() && property) {}
 #### [MapIterationInForEachLoop](http://sevntu-checkstyle.github.io/sevntu.checkstyle/apidocs/com/github/sevntu/checkstyle/checks/coding/MapIterationInForEachLoopCheck.html)
 
 Checks for unoptimised iterations over `Map`s. Check use of `map.values()`, `map.keySet()` and `map.entrySet()` against the use of the iterator produced to verify if another could be better.
+#### [MoveVariableInsideIfCheck](http://sevntu-checkstyle.github.io/sevntu.checkstyle/apidocs/com/github/sevntu/checkstyle/checks/coding/MoveVariableInsideIfCheck.html)
+
+Checks if a variable is declared outside an `if` block that is only used within that block.
+
+Valid:
+````
+if (condition) {
+    String variable = input.substring(1);
+    return method(variable);
+}
+return "";
+````
+
+Invalid:
+````
+String variable = input.substring(1);
+if (condition) {
+    return method(variable);
+}
+return "";
+````
+
+Example: [MoveVariableInsideIf.java](https://github.com/kemitix/kemitix-checkstyle-ruleset/blob/master/regressions/src/main/java/net/kemitix/checkstyle/regressions/MoveVariableInsideIf.java)
 #### [NameConventionForJunit4TestClasses](http://sevntu-checkstyle.github.io/sevntu.checkstyle/apidocs/com/github/sevntu/checkstyle/checks/coding/NameConventionForJunit4TestClassesCheck.html)
 
 Checks the names of JUnit test classes. Classes checked are those that have at least one method annotated with `Test` or `org.junit.Test`.

builder/src/main/resources/application.yml

@@ -1498,3 +1498,10 @@ rules:
         source: SEVNTU
         uri: http://sevntu-checkstyle.github.io/sevntu.checkstyle/apidocs/com/github/sevntu/checkstyle/checks/coding/WhitespaceBeforeArrayInitializerCheck.html
         reason: "TODO: enable"
+    -
+        name: MoveVariableInsideIfCheck
+        parent: TREEWALKER
+        level: TWEAKS
+        enabled: true
+        source: SEVNTU
+        uri: http://sevntu-checkstyle.github.io/sevntu.checkstyle/apidocs/com/github/sevntu/checkstyle/checks/coding/MoveVariableInsideIfCheck.html

builder/src/main/resources/rules/MoveVariableInsideIfCheck.md

@@ -0,0 +1,22 @@
+
+Checks if a variable is declared outside an `if` block that is only used within that block.
+
+Valid:
+````
+if (condition) {
+    String variable = input.substring(1);
+    return method(variable);
+}
+return "";
+````
+
+Invalid:
+````
+String variable = input.substring(1);
+if (condition) {
+    return method(variable);
+}
+return "";
+````
+
+Example: [MoveVariableInsideIf.java](https://github.com/kemitix/kemitix-checkstyle-ruleset/blob/master/regressions/src/main/java/net/kemitix/checkstyle/regressions/MoveVariableInsideIf.java)

regressions/src/main/java/net/kemitix/checkstyle/regressions/MoveVariableInsideIf.java

@@ -0,0 +1,65 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.checkstyle.regressions;
+
+/**
+ * Regression demo for {@code MoveVariableInsideIfCheck}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+class MoveVariableInsideIf {
+
+    private String input = "1";
+
+    private boolean condition;
+
+    private String method(final String variable) {
+        return "value";
+    }
+
+    /**
+     * Fails if not suppressed.
+     *
+     * @return value
+     */
+    @SuppressWarnings("movevariableinsideif")
+    String invalid() {
+        String variable = input.substring(1);
+        if (condition) {
+            return method(variable);
+        }
+        return "";
+    }
+
+    /**
+     * Rewrite {@link #invalid()} as this to pass.
+     *
+     * @return value
+     */
+    String valid() {
+        if (condition) {
+            String variable = input.substring(1);
+            return method(variable);
+        }
+        return "";
+    }
+}

ruleset/src/main/resources/net/kemitix/checkstyle-4-tweaks.xml

@@ -175,6 +175,7 @@
 <module name="UniformEnumConstantName"/>
 <module name="UselessSingleCatch"/>
 <module name="UselessSuperCtorCall"/>
+<module name="MoveVariableInsideIfCheck"/>
 
     </module><!-- /TreeWalker -->
 

ruleset/src/main/resources/net/kemitix/checkstyle-5-complexity.xml

@@ -228,6 +228,7 @@
 <module name="UniformEnumConstantName"/>
 <module name="UselessSingleCatch"/>
 <module name="UselessSuperCtorCall"/>
+<module name="MoveVariableInsideIfCheck"/>
 
     </module><!-- /TreeWalker -->