Disallow useless string concatenation (#35)

Author: MidnightDesign

Eventjet/ruleset.xml

@@ -83,13 +83,14 @@
     <!-- Forbid `$this` inside static function -->
     <rule ref="Squiz.Scope.StaticThisUsage"/>
 
-    <!-- Force whitespace before and after concatenation -->
+    <!-- String concatenation -->
     <rule ref="Squiz.Strings.ConcatenationSpacing">
         <properties>
             <property name="spacing" value="1"/>
             <property name="ignoreNewlines" value="true"/>
         </properties>
     </rule>
+    <rule ref="Generic.Strings.UnnecessaryStringConcat"/>
 
     <!-- Forbid spaces in type casts -->
     <rule ref="Squiz.WhiteSpace.CastSpacing"/>

php-cs-fixer-rules.php

@@ -64,6 +64,7 @@
     'no_trailing_comma_in_singleline' => true,
     'no_unused_imports' => true,
     'no_useless_else' => true,
+    'no_useless_concat_operator' => true,
     'nullable_type_declaration_for_default_null_value' => true,
     'ordered_imports' => [
         'imports_order' => ['class', 'function', 'const'],

tests/fixtures/invalid/useless-concat.php

@@ -0,0 +1,5 @@
+<?php
+
+declare(strict_types=1);
+
+echo 'a' . 'b';