Fix file_get_contents warning in ContextFactory

Author: dunglas

src/Types/ContextFactory.php

@@ -37,13 +37,19 @@ final class ContextFactory
      * @see Context for more information on Contexts.
      *
      * @return Context
+     *
+     * @throws \InvalidArgumentException
      */
     public function createFromReflector(\Reflector $reflector)
     {
         if (method_exists($reflector, 'getDeclaringClass')) {
             $reflector = $reflector->getDeclaringClass();
         }
+
         $fileName = $reflector->getFileName();
+        if (!$fileName) {
+            throw new \InvalidArgumentException('There is no file name associated with this reflector.');
+        }
 
         return $this->createForNamespace($reflector->getNamespaceName(), file_get_contents($fileName));
     }

tests/unit/Types/ContextFactoryTest.php

@@ -149,6 +149,16 @@ public function bar()
 
             $this->assertSame([], $context->getNamespaceAliases());
         }
+
+        /**
+         * @expectedException \InvalidArgumentException
+         * @covers ::createFromReflector
+         */
+        public function testThrowExceptionWhenEmptyFileName()
+        {
+            $fixture = new ContextFactory();
+            $fixture->createFromReflector(new \ReflectionClass('stdClass'));
+        }
     }
 }