Add test for #5593

tests/_files/mock-object/AnInterfaceForIssue5593.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\MockObject;
+
+interface AnInterfaceForIssue5593
+{
+    public function doSomething(): AnotherInterfaceForIssue5593;
+}

tests/_files/mock-object/AnotherInterfaceForIssue5593.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\MockObject;
+
+interface AnotherInterfaceForIssue5593
+{
+    public function doSomethingElse(): static;
+}

tests/unit/Framework/MockObject/ReturnValueGeneratorTest.php

@@ -18,9 +18,12 @@
 use PHPUnit\Framework\Attributes\Group;
 use PHPUnit\Framework\Attributes\Small;
 use PHPUnit\Framework\Attributes\TestDox;
+use PHPUnit\Framework\Attributes\Ticket;
 use PHPUnit\Framework\TestCase;
 use PHPUnit\TestFixture\MockObject\AnInterface;
+use PHPUnit\TestFixture\MockObject\AnInterfaceForIssue5593;
 use PHPUnit\TestFixture\MockObject\AnotherInterface;
+use PHPUnit\TestFixture\MockObject\AnotherInterfaceForIssue5593;
 use PHPUnit\TestFixture\MockObject\YetAnotherInterface;
 use stdClass;
 
@@ -162,6 +165,22 @@ public function test_Generates_new_instance_of_test_stub_for_static(): void
         $this->assertInstanceOf($stubClassName, $this->generate('static', $stubClassName));
     }
 
+    #[Ticket('https://github.com/sebastianbergmann/phpunit/issues/5593')]
+    public function test_Generates_new_instance_of_test_stub_for_static_when_used_recursively(): void
+    {
+        $a = $this->createStub(AnInterfaceForIssue5593::class);
+
+        $this->assertInstanceOf(AnInterfaceForIssue5593::class, $a);
+
+        $b = $a->doSomething();
+
+        $this->assertInstanceOf(AnotherInterfaceForIssue5593::class, $b);
+
+        $c = $b->doSomethingElse();
+
+        $this->assertInstanceOf(AnotherInterfaceForIssue5593::class, $c);
+    }
+
     #[DataProvider('unionProvider')]
     #[TestDox('Generates $expected for $union')]
     public function test_Generates_return_value_for_union(mixed $expected, string $union): void