Fix autowiring null

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Fixed
+  * [#1081](https://github.com/Behat/Behat/pull/1081): Do not use isset to be
+    able to check for intentional `null` values when autowiring contexts
 
 ### Added
   * [#1144](https://github.com/Behat/Behat/pull/1144) : Support for arrays as context parameters

features/autowire.feature

@@ -106,6 +106,41 @@ Feature: Helper services autowire
     When I run "behat --no-colors -f progress features/autowire.feature"
     Then it should pass
 
+  Scenario: Null arguments should be skipped
+    Given a file named "behat.yaml" with:
+      """
+      default:
+        suites:
+          default:
+            contexts:
+              - FeatureContext:
+                  name: null
+            services: ServiceContainer
+            autowire: true
+      """
+    And a file named "features/autowire.feature" with:
+      """
+      Feature:
+        Scenario:
+          Given a step
+      """
+    And a file named "features/bootstrap/FeatureContext.php" with:
+      """
+      <?php use Behat\Behat\Context\Context;
+
+      class FeatureContext implements Context {
+          public function __construct($name, Service1 $s1, Service3 $s3)
+          {
+              PHPUnit\Framework\Assert::assertNull($name);
+          }
+
+          /** @Given a step */
+          public function aStep() {}
+      }
+      """
+    When I run "behat --no-colors -f progress features/autowire.feature"
+    Then it should pass
+
   Scenario: Unregistered services as constructor arguments
     Given a file named "features/autowire.feature" with:
       """

src/Behat/Behat/HelperContainer/ArgumentAutowirer.php

@@ -14,6 +14,7 @@
 use Psr\Container\ContainerInterface;
 use ReflectionFunctionAbstract;
 use ReflectionParameter;
+use ReflectionException;
 
 /**
  * Automatically wires arguments of a given function from inside the container by using type-hitns.
@@ -72,6 +73,18 @@ public function autowireArguments(ReflectionFunctionAbstract $reflection, array
      */
     private function isArgumentWireable(array $arguments, $index, ReflectionParameter $parameter)
     {
-        return !isset($arguments[$index]) && !isset($arguments[$parameter->getName()]) && $parameter->getClass();
+        if (isset($arguments[$index]) || array_key_exists($index, $arguments)) {
+            return false;
+        }
+
+        if (isset($arguments[$parameter->getName()]) || array_key_exists($parameter->getName(), $arguments)) {
+            return false;
+        }
+
+        try {
+            return (bool) $parameter->getClass();
+        } catch (ReflectionException $e) {
+            return false;
+        }
     }
 }

src/Behat/Testwork/Argument/MixedArgumentOrganiser.php

@@ -13,6 +13,7 @@
 use ReflectionFunctionAbstract;
 use ReflectionClass;
 use ReflectionParameter;
+use ReflectionException;
 
 /**
  * Organises function arguments using its reflection.
@@ -225,7 +226,11 @@ private function filterApplicableTypehintedParameters(array $parameters)
                 continue;
             }
 
-            $reflectionClass = $parameter->getClass();
+            try {
+                $reflectionClass = $parameter->getClass();
+            } catch (ReflectionException $e) {
+                continue;
+            }
 
             if (!$reflectionClass) {
                 continue;