Implement LooseBooleanMutator (#27)

* Implement LooseBooleanMutator

* ignore isTrue()/isFalse() with arguments

* Update LooseBooleanMutatorTest.php

* cs

Author: staabm

resources/infection.json5

@@ -12,6 +12,7 @@
   },
   "mutators": {
     "@default": false,
+    "PHPStan\\Infection\\LooseBooleanMutator": true,
     "PHPStan\\Infection\\TrinaryLogicMutator": true
   },
   "bootstrap": "build-infection/vendor/autoload.php"

src/Infection/LooseBooleanMutator.php

@@ -0,0 +1,75 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Infection;
+
+use Infection\Mutator\Definition;
+use Infection\Mutator\Mutator;
+use Infection\Mutator\MutatorCategory;
+use PhpParser\Node;
+use function count;
+use function in_array;
+
+/**
+ * @implements Mutator<Node\Expr\MethodCall>
+ */
+final class LooseBooleanMutator implements Mutator
+{
+
+	public static function getDefinition(): Definition
+	{
+		return new Definition(
+			<<<'TXT'
+				Replaces boolean Type->isTrue()/isFalse() with Type->toBoolean()->isTrue()/isFalse() to check loose comparisons coverage.
+				TXT
+			,
+			MutatorCategory::ORTHOGONAL_REPLACEMENT,
+			null,
+			<<<'DIFF'
+				- $type->isFalse()->yes();
+				+ $type->isBoolean()->isFalse()->yes();
+			DIFF,
+		);
+	}
+
+	public function getName(): string
+	{
+		return self::class;
+	}
+
+	public function canMutate(Node $node): bool
+	{
+		if (!$node instanceof Node\Expr\MethodCall) {
+			return false;
+		}
+
+		if (!$node->name instanceof Node\Identifier) {
+			return false;
+		}
+
+		if (!in_array($node->name->name, ['isTrue', 'isFalse'], true)) {
+			return false;
+		}
+
+		if (count($node->getArgs()) !== 0) {
+			return false;
+		}
+
+		if ($node->var instanceof Node\Expr\MethodCall) {
+			if (
+				$node->var->name instanceof Node\Identifier
+				&& in_array($node->var->name->name, ['toBoolean'], true)
+			) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	public function mutate(Node $node): iterable
+	{
+		$node->var = new Node\Expr\MethodCall($node->var, 'toBoolean');
+		yield $node;
+	}
+
+}

tests/Infection/LooseBooleanMutatorTest.php

@@ -0,0 +1,99 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Infection;
+
+use Infection\Testing\BaseMutatorTestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+#[CoversClass(LooseBooleanMutator::class)]
+final class LooseBooleanMutatorTest extends BaseMutatorTestCase
+{
+
+	/**
+	 * @param string|string[] $expected
+	 */
+	#[DataProvider('mutationsProvider')]
+	public function testMutator(string $input, $expected = []): void
+	{
+		$this->assertMutatesInput($input, $expected);
+	}
+
+	/**
+	 * @return iterable<string, array{0: string, 1?: string}>
+	 */
+	public static function mutationsProvider(): iterable
+	{
+		yield 'It mutates isFalse() into loose comparison' => [
+			<<<'PHP'
+				<?php
+
+				$type->isFalse()->yes();
+				PHP
+,
+			<<<'PHP'
+				<?php
+
+				$type->toBoolean()->isFalse()->yes();
+				PHP
+,
+		];
+
+		yield 'It mutates isTrue() into loose comparison' => [
+			<<<'PHP'
+				<?php
+
+				$type->isTrue()->yes();
+				PHP
+,
+			<<<'PHP'
+				<?php
+
+				$type->toBoolean()->isTrue()->yes();
+				PHP
+,
+		];
+
+		yield 'It skips already toBoolean() calls to prevent double repetition' => [
+			<<<'PHP'
+				<?php
+
+				$type->toBoolean()->isTrue()->yes();
+				PHP
+,
+		];
+
+		yield 'It skips non boolean Type calls' => [
+			<<<'PHP'
+				<?php
+
+				$type->isObject()->yes();
+				PHP
+,
+		];
+
+		yield 'skip isTrue() with arguments' => [
+			<<<'PHP'
+				<?php
+
+				$a->isTrue($b);
+				PHP
+,
+		];
+
+		yield 'skip isFalse() with arguments' => [
+			<<<'PHP'
+				<?php
+
+				$a->isFalse($b, $c);
+				PHP
+,
+		];
+	}
+
+	protected function getTestedMutatorClassName(): string
+	{
+		return LooseBooleanMutator::class;
+	}
+
+}

tests/phpt/infection-config-default.phpt

@@ -19,6 +19,7 @@ echo shell_exec($bin);
     },
     "mutators": {
         "@default": false,
+        "PHPStan\\Infection\\LooseBooleanMutator": true,
         "PHPStan\\Infection\\TrinaryLogicMutator": true
     },
     "bootstrap": "build-infection\/vendor\/autoload.php"

tests/phpt/infection-config.phpt

@@ -20,6 +20,7 @@ echo shell_exec($bin." --source-directory='more/files/' --timeout=180 --mutator-
     },
     "mutators": {
         "@default": false,
+        "PHPStan\\Infection\\LooseBooleanMutator": true,
         "PHPStan\\Infection\\TrinaryLogicMutator": true,
         "My\\Class": true
     },