Add tests for xaxis and yaxis angle conversions

This tricked me today, the "XAxis" and "YAxis" vectors are from different perspectives (yikes!). XAxis is from the perspective of grid north, and YAxis is from the perspective of project north. I'm following this convention because that's what buildingSMART docs do but just FYI they serve two different purposes!

src/ifcopenshell-python/test/util/test_geolocation.py

@@ -358,3 +358,43 @@ class TestAutoGlobal2Local(test.bootstrap.IFC4):
         m2[:, 1][0:3] = [-1, 0, 0]
         m2[:, 3][0:3] = [0, 3, 3]
         assert np.allclose(subject.auto_global2local(self.file, m2), m)
+
+
+class TestXAxis2Angle(test.bootstrap.IFC4):
+    def test_run(self):
+        assert subject.xaxis2angle(1, 0) == 0
+        assert subject.xaxis2angle(1, 1) == -45
+        assert subject.xaxis2angle(-1, 1) == -135
+        assert subject.xaxis2angle(1, -1) == 45
+        assert subject.xaxis2angle(-1, -1) == 135
+        assert np.isclose(subject.xaxis2angle(0.8660254, -0.5), 30)
+
+
+class TestAngle2XAxis(test.bootstrap.IFC4):
+    def test_run(self):
+        a = 0.707106781186
+        assert np.allclose(subject.angle2xaxis(0), (1, 0))
+        assert np.allclose(subject.angle2xaxis(-45), (a, a))
+        assert np.allclose(subject.angle2xaxis(-135), (-a, a))
+        assert np.allclose(subject.angle2xaxis(45), (a, -a))
+        assert np.allclose(subject.angle2xaxis(135), (-a, -a))
+
+
+class TestYAxis2Angle(test.bootstrap.IFC4):
+    def test_run(self):
+        assert subject.yaxis2angle(0, 1) == 0
+        assert np.isclose(subject.yaxis2angle(-0.5, 0.8660254), 30)
+        assert subject.yaxis2angle(1, 1) == -45
+        assert subject.yaxis2angle(-1, 1) == 45
+        assert subject.yaxis2angle(1, -1) == -135
+        assert subject.yaxis2angle(-1, -1) == 135
+
+
+class TestAngle2YAxis(test.bootstrap.IFC4):
+    def test_run(self):
+        a = 0.707106781186
+        assert np.allclose(subject.angle2yaxis(0), (0, 1))
+        assert np.allclose(subject.angle2yaxis(-45), (a, a))
+        assert np.allclose(subject.angle2yaxis(45), (-a, a))
+        assert np.allclose(subject.angle2yaxis(-135), (a, -a))
+        assert np.allclose(subject.angle2yaxis(135), (-a, -a))