def test_identity(self):
        assert CanvasUnit.from_pt(1).pt == 1
        assert CanvasUnit.from_in(1).inches == 1
        assert CanvasUnit.from_cm(1).cm == 1
        assert CanvasUnit.from_mm(1).mm == 1
        assert CanvasUnit.from_px(1).px == 1
        assert CanvasUnit.from_pango(1).pango == 1

        assert CanvasUnit.from_pt(2).pt == 2
        assert CanvasUnit.from_in(2).inches == 2
        assert CanvasUnit.from_cm(2).cm == 2
        assert CanvasUnit.from_mm(2).mm == 2
        assert CanvasUnit.from_px(2).px == 2
        assert CanvasUnit.from_pango(2).pango == 2
 def test_comparisons(self):
     assert CanvasUnit.from_in(1).pt > CanvasUnit.from_cm(1).pt
     assert CanvasUnit.from_cm(1).pt > CanvasUnit.from_mm(1).pt
     assert CanvasUnit.from_mm(1).pt > CanvasUnit.from_pt(1).pt
     assert CanvasUnit.from_pt(1).pt > CanvasUnit.from_px(1).pt
     assert CanvasUnit.from_px(1).pt > CanvasUnit.from_pango(1).pt
 def test_pango_scale_is_consistent_with_library(self):
     assert CanvasUnit.from_pt(2).pango == pangocffi.units_from_double(2)
     assert CanvasUnit.from_pango(512).pt == pangocffi.units_to_double(512)