AddInstanceofAssertForNullableInstanceRector.php

<?php

declare(strict_types=1);

namespace Rector\PHPUnit\CodeQuality\Rector\ClassMethod;

use PhpParser\Node;
use PhpParser\Node\Expr\MethodCall;
use PhpParser\Node\Expr\StaticCall;
use PhpParser\Node\Expr\Variable;
use PhpParser\Node\Stmt;
use PhpParser\Node\Stmt\ClassMethod;
use PhpParser\Node\Stmt\Expression;
use PhpParser\Node\Stmt\Foreach_;
use Rector\PHPUnit\CodeQuality\NodeAnalyser\NullableObjectAssignCollector;
use Rector\PHPUnit\CodeQuality\NodeFactory\AssertMethodCallFactory;
use Rector\PHPUnit\CodeQuality\TypeAnalyzer\SimpleTypeAnalyzer;
use Rector\PHPUnit\CodeQuality\ValueObject\VariableNameToType;
use Rector\PHPUnit\CodeQuality\ValueObject\VariableNameToTypeCollection;
use Rector\PHPUnit\NodeAnalyzer\TestsNodeAnalyzer;
use Rector\Rector\AbstractRector;
use Rector\RuleDoc\CodeSample\CodeSample;
use Rector\RuleDoc\RuleDefinition;

/**
 * @see \Rector\PHPUnit\Tests\CodeQuality\Rector\ClassMethod\AddInstanceofAssertForNullableInstanceRector\AddInstanceofAssertForNullableInstanceRectorTest
 */
final class AddInstanceofAssertForNullableInstanceRector extends AbstractRector
{
    public function __construct(
        private readonly TestsNodeAnalyzer $testsNodeAnalyzer,
        private readonly NullableObjectAssignCollector $nullableObjectAssignCollector,
        private readonly AssertMethodCallFactory $assertMethodCallFactory,
    ) {
    }

    public function getRuleDefinition(): RuleDefinition
    {
        return new RuleDefinition(
            'Add explicit instance assert between nullable object assign and method call on nullable object (spotted by PHPStan)',
            [
                new CodeSample(
                    <<<'CODE_SAMPLE'
use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function test()
    {
        $someObject = $this->getSomeObject();

        $value = $someObject->getSomeMethod();
    }

    private function getSomeObject(): ?SomeClass
    {
        if (mt_rand(0, 1)) {
            return new SomeClass();
        }

        return null;
    }
}
CODE_SAMPLE

                    ,
                    <<<'CODE_SAMPLE'
use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function test()
    {
        $someObject = $this->getSomeObject();
        $this->assertInstanceOf(SomeClass::class, $someObject);

        $value = $someObject->getSomeMethod();
    }

    private function getSomeObject(): ?SomeClass
    {
        if (mt_rand(0, 1)) {
            return new SomeClass();
        }

        return null;
    }
}
CODE_SAMPLE
                ),
            ]
        );
    }

    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [ClassMethod::class, Foreach_::class];
    }

    /**
     * @param ClassMethod|Foreach_ $node
     */
    public function refactor(Node $node): ?Node
    {
        if (! $this->testsNodeAnalyzer->isInTestClass($node)) {
            return null;
        }

        if ($node->stmts === [] || $node->stmts === null || count($node->stmts) < 2) {
            return null;
        }

        $hasChanged = false;
        $variableNameToTypeCollection = $this->nullableObjectAssignCollector->collect($node);

        $next = 0;
        foreach ($node->stmts as $key => $stmt) {
            // already asserted, e.g. in trait, where $this is not known as TestCase so the type is not narrowed
            $assertedVariableName = $this->matchAssertInstanceOfVariableName($stmt);
            if ($assertedVariableName !== null) {
                $assertedVariableNameToType = $variableNameToTypeCollection->matchByVariableName(
                    $assertedVariableName
                );
                if ($assertedVariableNameToType instanceof VariableNameToType) {
                    $variableNameToTypeCollection->remove($assertedVariableNameToType);
                }

                continue;
            }

            // has callable on nullable variables of already collected names?
            // a single statement can use multiple nullable variables at once
            $matchedNullableVariableNameToTypes = $this->matchNullableVariableNameToTypes(
                $stmt,
                $variableNameToTypeCollection
            );

            foreach ($matchedNullableVariableNameToTypes as $matchedNullableVariableNameToType) {
                // adding type here + popping the variable name out
                $assertInstanceOfExpression = $this->assertMethodCallFactory->createAssertInstanceOf(
                    $matchedNullableVariableNameToType
                );
                array_splice($node->stmts, $key + $next, 0, [$assertInstanceOfExpression]);

                $hasChanged = true;

                // from now on, the variable is not nullable, remove to avoid double asserts
                $variableNameToTypeCollection->remove($matchedNullableVariableNameToType);

                ++$next;
            }
        }

        if (! $hasChanged) {
            return null;
        }

        return $node;
    }

    private function matchAssertInstanceOfVariableName(Stmt $stmt): ?string
    {
        if (! $stmt instanceof Expression) {
            return null;
        }

        $call = $stmt->expr;
        if (! $call instanceof MethodCall && ! $call instanceof StaticCall) {
            return null;
        }

        if (! $this->isName($call->name, 'assertInstanceOf')) {
            return null;
        }

        if ($call->isFirstClassCallable()) {
            return null;
        }

        $args = $call->getArgs();
        if (! isset($args[1]) || ! $args[1]->value instanceof Variable) {
            return null;
        }

        return $this->getName($args[1]->value);
    }

    /**
     * @return VariableNameToType[]
     */
    private function matchNullableVariableNameToTypes(
        Stmt $stmt,
        VariableNameToTypeCollection $variableNameToTypeCollection
    ): array {
        $matchedNullableVariableNameToTypes = [];
        $matchedVariableNames = [];

        $this->traverseNodesWithCallable($stmt, function (Node $node) use (
            $variableNameToTypeCollection,
            &$matchedNullableVariableNameToTypes,
            &$matchedVariableNames
        ): ?int {
            if (! $node instanceof MethodCall) {
                return null;
            }

            if (! $node->var instanceof Variable) {
                return null;
            }

            $variableType = $this->getType($node->var);
            if (! SimpleTypeAnalyzer::isNullableType($variableType)) {
                return null;
            }

            $variableName = $this->getName($node->var);
            if ($variableName === null) {
                return null;
            }

            // avoid duplicated assert for the same variable used multiple times in one statement
            if (in_array($variableName, $matchedVariableNames, true)) {
                return null;
            }

            $matchedNullableVariableNameToType = $variableNameToTypeCollection->matchByVariableName($variableName);
            if (! $matchedNullableVariableNameToType instanceof VariableNameToType) {
                return null;
            }

            $matchedVariableNames[] = $variableName;
            $matchedNullableVariableNameToTypes[] = $matchedNullableVariableNameToType;

            return null;
        });

        return $matchedNullableVariableNameToTypes;
    }
}