Enhancement: Implement UnwrapStrtolower mutator

src/Mutator/Unwrap/UnwrapStrToLower.php

@@ -0,0 +1,54 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2018, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Mutator\Unwrap;
+
+use PhpParser\Node;
+
+/**
+ * @internal
+ */
+final class UnwrapStrToLower extends AbstractUnwrapMutator
+{
+    protected function getFunctionName(): string
+    {
+        return 'strtolower';
+    }
+
+    protected function getParameterIndex(Node $node): \Generator
+    {
+        yield 0;
+    }
+}

src/Mutator/Util/MutatorProfile.php

@@ -195,6 +195,7 @@ final class MutatorProfile
         Mutator\Unwrap\UnwrapArrayReplace::class,
         Mutator\Unwrap\UnwrapArrayReverse::class,
         Mutator\Unwrap\UnwrapStrRepeat::class,
+        Mutator\Unwrap\UnwrapStrToLower::class,
     ];
 
     public const DEFAULT = [
@@ -325,5 +326,6 @@ final class MutatorProfile
         'UnwrapArrayReplace' => Mutator\Unwrap\UnwrapArrayReplace::class,
         'UnwrapArrayReverse' => Mutator\Unwrap\UnwrapArrayReverse::class,
         'UnwrapStrRepeat' => Mutator\Unwrap\UnwrapStrRepeat::class,
+        'UnwrapStrToLower' => Mutator\Unwrap\UnwrapStrToLower::class,
     ];
 }

tests/Mutator/Unwrap/UnwrapStrToLowerTest.php

@@ -0,0 +1,181 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2018, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Tests\Mutator\Unwrap;
+
+use Infection\Tests\Mutator\AbstractMutatorTestCase;
+
+/**
+ * @internal
+ */
+final class UnwrapStrToLowerTest extends AbstractMutatorTestCase
+{
+    /**
+     * @dataProvider provideMutationCases
+     */
+    public function test_mutator($input, $expected = null): void
+    {
+        $this->doTest($input, $expected);
+    }
+
+    public function provideMutationCases(): \Generator
+    {
+        yield 'It mutates correctly when provided with a string' => [
+            <<<'PHP'
+<?php
+
+$a = strtolower('Good Afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'Good Afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly when provided with a constant' => [
+            <<<'PHP'
+<?php
+
+$a = strtolower(\Class_With_Const::Const);
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = \Class_With_Const::Const;
+PHP
+        ];
+
+        yield 'It mutates correctly when a backslash is in front of strtolower' => [
+            <<<'PHP'
+<?php
+
+$a = \strtolower('Good Afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'Good Afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly within if statements' => [
+            <<<'PHP'
+<?php
+
+$a = 'Good Afternoon!';
+if (strtolower($a) === $a) {
+    return true;
+}
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'Good Afternoon!';
+if ($a === $a) {
+    return true;
+}
+PHP
+        ];
+
+        yield 'It mutates correctly when strtolower is wrongly capitalized' => [
+            <<<'PHP'
+<?php
+
+$a = sTrToLoWeR('Good Afternoon!');
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = 'Good Afternoon!';
+PHP
+        ];
+
+        yield 'It mutates correctly when strtolower uses another function as input' => [
+            <<<'PHP'
+<?php
+
+$a = strtolower($foo->bar());
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = $foo->bar();
+PHP
+        ];
+
+        yield 'It mutates correctly when provided with a more complex situation' => [
+            <<<'PHP'
+<?php
+
+$a = strtolower(array_reduce($words, function (string $carry, string $item) {
+    return $carry . substr($item, 0, 1);
+}));
+PHP
+            ,
+            <<<'PHP'
+<?php
+
+$a = array_reduce($words, function (string $carry, string $item) {
+    return $carry . substr($item, 0, 1);
+});
+PHP
+        ];
+
+        yield 'It does not mutate other str* calls' => [
+            <<<'PHP'
+<?php
+
+$a = strtoupper('Good Afternoon!');
+PHP
+        ];
+
+        yield 'It does not mutate functions named strtolower' => [
+            <<<'PHP'
+<?php
+
+function strtolower($string)
+{
+}
+PHP
+        ];
+    }
+}