unclear test - maybe parametrise?

[mini-kep]

unclear test - maybe parametrise?

[epogrebnyak]

See shorter expression here 44e704c.

Instead of

for row in read_test_data(): 
         if row['freq'] == random_freq and row['name'] not in expected_result: 
             expected_result.append(row['name']) 
expected_result = sorted(expected_result) 

can have:

names = set([d['name'] for d in self.test_data if d['freq']==freq])            
expected_result = sorted(names)

Similar expression was in test earlier.