[3818] Zwiększenie pokrycia testami.

https://gist.github.com/lukkolstx/bd8e4a7df17657f4a60d
Please add some more tests with `float` numbers.

Check this data: [5.234, -2.34, 1.113, 3.2412, -0.1853, 0.54, 0.797]
[assertAlmostEqual](https://docs.python.org/2/library/unittest.html#unittest.TestCase.assertAlmostEqual)