Add BrowserKitAssertionTraitReturnTypeExtension

extension.neon

@@ -193,6 +193,11 @@ services:
 		factory: PHPStan\Type\Symfony\EnvelopeReturnTypeExtension
 		tags: [phpstan.broker.dynamicMethodReturnTypeExtension]
 
+	# BrowserKitAssertionTrait::getClient() return type
+	-
+		class: PHPStan\Type\Symfony\BrowserKitAssertionTraitReturnTypeExtension
+		tags: [phpstan.broker.expressionTypeResolverExtension]
+
 	# Messenger HandleTrait::handle() return type
 	-
 		class: PHPStan\Type\Symfony\MessengerHandleTraitReturnTypeExtension

src/Type/Symfony/BrowserKitAssertionTraitReturnTypeExtension.php

@@ -0,0 +1,68 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Symfony;
+
+use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Identifier;
+use PHPStan\Analyser\Scope;
+use PHPStan\Type\ExpressionTypeResolverExtension;
+use PHPStan\Type\NullType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\UnionType;
+use function count;
+
+final class BrowserKitAssertionTraitReturnTypeExtension implements ExpressionTypeResolverExtension
+{
+
+	private const TRAIT_NAME = 'Symfony\Bundle\FrameworkBundle\Test\BrowserKitAssertionsTrait';
+	private const TRAIT_METHOD_NAME = 'getClient';
+
+	public function getType(Expr $expr, Scope $scope): ?Type
+	{
+		if ($this->isSupported($expr, $scope)) {
+			$args = $expr->getArgs();
+			if (count($args) > 0) {
+				return TypeCombinator::intersect(
+					$scope->getType($args[0]->value),
+					new UnionType([
+						new ObjectType('Symfony\Component\BrowserKit\AbstractBrowser'),
+						new NullType(),
+					]),
+				);
+			}
+
+			return new ObjectType('Symfony\Component\BrowserKit\AbstractBrowser');
+		}
+
+		return null;
+	}
+
+	/**
+	 * @phpstan-assert-if-true =MethodCall $expr
+	 */
+	private function isSupported(Expr $expr, Scope $scope): bool
+	{
+		if (!($expr instanceof MethodCall) || !($expr->name instanceof Identifier) || $expr->name->name !== self::TRAIT_METHOD_NAME) {
+			return false;
+		}
+
+		if (!$scope->isInClass()) {
+			return false;
+		}
+
+		$reflectionClass = $scope->getClassReflection()->getNativeReflection();
+
+		if (!$reflectionClass->hasMethod(self::TRAIT_METHOD_NAME)) {
+			return false;
+		}
+
+		$methodReflection = $reflectionClass->getMethod(self::TRAIT_METHOD_NAME);
+		$declaringClassReflection = $methodReflection->getBetterReflection()->getDeclaringClass();
+
+		return $declaringClassReflection->getName() === self::TRAIT_NAME;
+	}
+
+}

tests/Type/Symfony/ExtensionTest.php

@@ -14,6 +14,7 @@ class ExtensionTest extends TypeInferenceTestCase
 	/** @return mixed[] */
 	public function dataFileAsserts(): iterable
 	{
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/browserkit_assertion_trait.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/messenger_handle_trait.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/envelope_all.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/header_bag_get.php');

tests/Type/Symfony/data/browserkit_assertion_trait.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types = 1);
+
+namespace BrowserKitAssertionTrait;
+
+use Symfony\Bundle\FrameworkBundle\Test\BrowserKitAssertionsTrait;
+use Symfony\Component\BrowserKit\AbstractBrowser;
+use function PHPStan\Testing\assertType;
+
+class Foo {
+    use BrowserKitAssertionsTrait;
+
+	/**
+	 * @param mixed $mixed
+	 */
+    public function test(AbstractBrowser $browser, ?AbstractBrowser $nullableBrowser, $mixed)
+    {
+        assertType('Symfony\Component\BrowserKit\AbstractBrowser', $this->getClient());
+        assertType('null', $this->getClient(null));
+        assertType('Symfony\Component\BrowserKit\AbstractBrowser', $this->getClient($browser));
+        assertType('Symfony\Component\BrowserKit\AbstractBrowser|null', $this->getClient($nullableBrowser));
+        assertType('Symfony\Component\BrowserKit\AbstractBrowser|null', $this->getClient($mixed));
+    }
+}