Closes #5048

ChangeLog-10.4.md

@@ -2,6 +2,12 @@
 
 All notable changes of the PHPUnit 10.4 release series are documented in this file using the [Keep a CHANGELOG](https://keepachangelog.com/) principles.
 
+## [10.4.2] - 2023-MM-DD
+
+### Fixed
+
+* [#5048](https://github.com/sebastianbergmann/phpunit/issues/5048): Methods that return `never` cannot be doubled
+
 ## [10.4.1] - 2023-10-08
 
 ### Fixed
@@ -41,5 +47,6 @@ All notable changes of the PHPUnit 10.4 release series are documented in this fi
 * `PHPUnit\TextUI\Configuration\Configuration::cliArgument()` and `PHPUnit\TextUI\Configuration\Configuration::hasCliArgument()`
 * `PHPUnit\Framework\Constraint\Constraint::exporter()`
 
+[10.4.2]: https://github.com/sebastianbergmann/phpunit/compare/10.4.1...10.4
 [10.4.1]: https://github.com/sebastianbergmann/phpunit/compare/10.4.0...10.4.1
 [10.4.0]: https://github.com/sebastianbergmann/phpunit/compare/10.3.5...10.4.0

src/Framework/MockObject/Exception/NeverReturningMethodException.php

@@ -0,0 +1,34 @@
+<?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\Framework\MockObject;
+
+use function sprintf;
+use RuntimeException;
+
+/**
+ * @no-named-arguments Parameter names are not covered by the backward compatibility promise for PHPUnit
+ */
+final class NeverReturningMethodException extends RuntimeException implements Exception
+{
+    /**
+     * @psalm-param class-string $className
+     * @psalm-param non-empty-string $methodName
+     */
+    public function __construct(string $className, string $methodName)
+    {
+        parent::__construct(
+            sprintf(
+                'Method %s::%s() is declared to never return',
+                $className,
+                $methodName,
+            ),
+        );
+    }
+}

src/Framework/MockObject/Runtime/Invocation.php

@@ -105,6 +105,13 @@ public function parameters(): array
      */
     public function generateReturnValue(): mixed
     {
+        if ($this->returnType === 'never') {
+            throw new NeverReturningMethodException(
+                $this->className,
+                $this->methodName,
+            );
+        }
+
         if ($this->isReturnTypeNullable || $this->proxiedCall) {
             return null;
         }

tests/_files/mock-object/InterfaceWithNeverReturningMethod.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 InterfaceWithNeverReturningMethod
+{
+    public function m(): never;
+}

tests/unit/Framework/MockObject/TestDoubleTestCase.php

@@ -14,6 +14,7 @@
 use PHPUnit\Framework\TestCase;
 use PHPUnit\TestFixture\MockObject\ExtendableClassWithCloneMethod;
 use PHPUnit\TestFixture\MockObject\InterfaceWithMethodThatExpectsObject;
+use PHPUnit\TestFixture\MockObject\InterfaceWithNeverReturningMethod;
 use PHPUnit\TestFixture\MockObject\InterfaceWithReturnTypeDeclaration;
 use stdClass;
 
@@ -222,6 +223,16 @@ public function testOriginalCloneMethodCanOptionallyBeCalledWhenTestDoubleObject
         clone $double;
     }
 
+    public function testThrowsExceptionWhenMethodWithNeverReturnTypeDeclarationIsCalled(): void
+    {
+        $double = $this->createTestDouble(InterfaceWithNeverReturningMethod::class);
+
+        $this->expectException(NeverReturningMethodException::class);
+        $this->expectExceptionMessage('Method PHPUnit\TestFixture\MockObject\InterfaceWithNeverReturningMethod::m() is declared to never return');
+
+        $double->m();
+    }
+
     /**
      * @psalm-template RealInstanceType of object
      *