Tests for Vector functions: cross, angle, angle_signed, rotation_difference, project, lerp, rotate, dot.
Looks good, noted some issues.
And I think it would be good to add some error cases too. (zero area vectors, float('nan') vectors even)
*picky* pep8, spaces around operators a = b
I'd like to avoid values like 5.600000381469727 - they could even fail to compare on different systems.
Suggest to use assertAlmostEqual() then pass in the distance between the 2 vectors.