Cover #24 with a test

This is currently a weird behavior, but we'll keep it for now because it makes sense logically.

See PHP-DI/PHP-DI#628 (comment) for more details.

tests/InvokerTest.php

@@ -286,6 +286,29 @@ public function should_resolve_callable_from_container_with_class_name_in_scope_
         $this->assertTrue($fixture->wasCalled);
     }
 
+    /**
+     * Mixing named parameters with positioned parameters is a really bad idea.
+     * When that happens, the positioned parameters have the highest priority and will
+     * override named parameters in case of conflicts.
+     *
+     * Note that numeric array indexes ignore string indexes. In our example, the
+     * 'bar' value has the position `0`, which overrides the 'foo' value.
+     *
+     * @test
+     */
+    public function positioned_parameters_have_the_highest_priority()
+    {
+        $factory = function ($foo, $bar = 300) {
+            return [$foo, $bar];
+        };
+        $result = $this->invoker->call($factory, [
+            'foo' => 'foo',
+            'bar',
+        ]);
+
+        $this->assertEquals(['bar', 300], $result);
+    }
+
     /**
      * @test
      */