Youshido\GraphQL\Execution\Request::setVariables PHP Method

    public function setVariables($variables)
    {
        if (!is_array($variables)) {
            $variables = json_decode($variables, true);
        }
        $this->variables = $variables;
        return $this;
    }

 public function testSetVariableParseJson()
 {
     $variables = '{"foo": "bar"}';
     $expectedVariableArray = ['foo' => 'bar'];
     $request = new Request([], $variables);
     $this->assertEquals($expectedVariableArray, $request->getVariables());
     $request = new Request();
     $request->setVariables($variables);
     $this->assertEquals($expectedVariableArray, $request->getVariables());
 }