Unittest (sometimes) fails because floating-point imprecision

Question

I have a class Vector that represents a point in 3-dimensional space. This vector has a method normalize(self, length = 1) which scales the vector down/up

Answer 1

In general, you should not assert equality for floats. Instead, ensure that the result is within certain bounds, e.g.:

self.assertTrue(abs(vec.normalize(5).length - 5) < 0.001)