Check whether method has return typehint

Author: adaamz

Diff for: src/Rules/Methods/MissingMethodReturnTypehintRule.php

@@ -0,0 +1,60 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Methods;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\MixedType;
+
+final class MissingMethodReturnTypehintRule implements \PHPStan\Rules\Rule
+{
+
+    /**
+     * @return string Class implementing \PhpParser\Node
+     */
+    public function getNodeType(): string
+    {
+        return \PhpParser\Node\Stmt\ClassMethod::class;
+    }
+
+    /**
+     * @param \PhpParser\Node $node
+     * @param \PHPStan\Analyser\Scope $scope
+     *
+     * @return string[] errors
+     */
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (!$scope->isInClass()) {
+            throw new \PHPStan\ShouldNotHappenException();
+        }
+
+        $methodReflection = $scope->getClassReflection()->getNativeMethod($node->name);
+
+        $messages = [];
+
+        $message = $this->checkMethodReturnType($methodReflection);
+        if ($message !== null) {
+	        $messages[] = $message;
+        }
+
+        return $messages;
+    }
+
+    private function checkMethodReturnType(MethodReflection $methodReflection): ?string
+    {
+    	$returnType = $methodReflection->getReturnType();
+
+    	if ($returnType instanceof MixedType && !$returnType->isExplicitMixed()) {
+		    return sprintf(
+			    'Method %s::%s() has no return typehint specified',
+			    $methodReflection->getDeclaringClass()->getName(),
+			    $methodReflection->getName()
+		    );
+	    }
+
+	    return null;
+    }
+
+}

Diff for: tests/Rules/Methods/MissingMethodReturnTypehintRuleTest.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Methods;
+
+class MissingMethodReturnTypehintRuleTest extends \PHPStan\Testing\RuleTestCase
+{
+
+	protected function getRule(): \PHPStan\Rules\Rule
+	{
+		return new MissingMethodReturnTypehintRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/missing-method-return-typehint.php'], [
+			[
+				'Method MissingMethodReturnTypehint\FooInterface::getFoo() has no return typehint specified',
+				8,
+			],
+			[
+				'Method MissingMethodReturnTypehint\FooParent::getBar() has no return typehint specified',
+				15,
+			],
+			[
+				'Method MissingMethodReturnTypehint\Foo::getFoo() has no return typehint specified',
+				25,
+			],
+			[
+				'Method MissingMethodReturnTypehint\Foo::getBar() has no return typehint specified',
+				33,
+			],
+		]);
+	}
+
+}

Diff for: tests/Rules/Methods/data/missing-method-return-typehint.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace MissingMethodReturnTypehint;
+
+interface FooInterface
+{
+
+    public function getFoo($p1);
+
+}
+
+class FooParent
+{
+
+    public function getBar($p2)
+    {
+
+    }
+
+}
+
+class Foo extends FooParent implements FooInterface
+{
+
+    public function getFoo($p1)
+    {
+
+    }
+
+    /**
+     * @param $p2
+     */
+    public function getBar($p2)
+    {
+
+    }
+
+    public function getBaz(): bool
+    {
+        return false;
+    }
+
+}