diff --git a/snsim/geo_utils.py b/snsim/geo_utils.py
index 10c3215..1249695 100644
--- a/snsim/geo_utils.py
+++ b/snsim/geo_utils.py
@@ -17,6 +17,7 @@ def _format_corner(corner, RA):
     #       - RA_0 < RA_1
     #       - RA_3 < RA_2
     #       - RA_0 and RA_3 on the same side of the field center
+    # corner[fields, corner, subfields, ra/dec]
     
     sign = (corner[:, 3, :, 0] - RA[:, None]) * (corner[:, 0, :, 0] - RA[:, None]) < 0
     comp = corner[:, 0, :, 0] < corner[:, 3, :, 0]
@@ -46,7 +47,12 @@ def _compute_area(polygon):
 
 
 def _compute_polygon(corners):
-    """Create polygon on a sphere, check for edges conditions."""
+    """Create polygon on a sphere, check for edges conditions.
+    
+    Notes
+    -----
+    corners[corner, subfields, ra/dec]
+    """
     
     # Create polygons
     polygons = gpd.GeoSeries([shp_geo.Polygon(corners[:, j, :]) for j in range(corners.shape[1])])
diff --git a/snsim/tests/test_geout.py b/snsim/tests/test_geout.py
new file mode 100644
index 0000000..ae88de6
--- /dev/null
+++ b/snsim/tests/test_geout.py
@@ -0,0 +1,26 @@
+import numpy as np
+import shapely.geometry as shp_geo
+from numpy.testing import assert_almost_equal
+from snsim import geo_utils as geo_ut
+
+def test_compute_area():
+    corners = np.array([[[0, np.pi / 2]], [[2 * np.pi, np.pi / 2]] ,
+                        [[2 * np.pi, -np.pi / 2]], [[0, -np.pi / 2]]])
+    
+    polygon = geo_ut._compute_polygon(corners)
+    
+    area = geo_ut._compute_area(polygon)
+    assert_almost_equal(area, 4 * np.pi)
+    
+    
+def test_compute_polygon():
+    
+    # Regular polygon
+    corners = np.array([[[np.pi - 0.02, 0.02]], [[np.pi + 0.02, 0.02]] ,
+                        [[np.pi + 0.02, -0.02]], [[np.pi - 0.02, -0.02]]])
+    
+    polygon = geo_ut._compute_polygon(corners)
+    
+    ra = np.random.uniform(0, 2 * np.pi, 10
+    
+    
\ No newline at end of file