def test_to_json_solved(self):
     runner = TestRunner(
         solution='foo = 1',
         tests='>>> foo\n1'
     )
     runner.run()
     data = json.loads(runner.to_json())
     self.assertEqual(
         {'solved', 'results', 'printed'},
         data.keys()
     )
     self.assertTrue(data['solved'])
     self.assertEqual(
         [{
             'call': 'foo',
             'expected': '1',
             'received': '1',
             'correct': True
         }],
         data['results']
     )
     self.assertEqual('', data['printed'])