diff --git a/tests/test_stm.py b/tests/test_stm.py
index 91a6944..e19c77c 100644
--- a/tests/test_stm.py
+++ b/tests/test_stm.py
@@ -7,8 +7,11 @@
 import xarray as xr
 from shapely import geometry
 
+from stmtools.stm import _validate_coords
+
 path_multi_polygon = Path(__file__).parent / "./data/multi_polygon.gpkg"
 
+
 @pytest.fixture
 def stmat_rd():
     # A STM with rd coordinates
@@ -45,6 +48,7 @@ def stmat_only_point():
         coords=dict(lon=(["space"], da.arange(npoints)), lat=(["space"], da.arange(npoints))),
     ).unify_chunks()
 
+
 @pytest.fixture
 def stmat_wrong_space_label():
     npoints = 10
@@ -110,7 +114,7 @@ def test_time_dim_exists(self, stmat_only_point):
     def test_time_dim_size_one(self, stmat_only_point):
         stm_reg = stmat_only_point.stm.regulate_dims()
         assert stm_reg.dims["time"] == 1
-    
+
     def test_time_dim_customed_label(self, stmat_wrong_space_label):
         stm_reg = stmat_wrong_space_label.stm.regulate_dims(space_label="space2")
         assert stm_reg.dims["time"] == 1
@@ -128,6 +132,30 @@ def test_subset_works_after_regulate_dims(self, stmat_only_point):
         stm_reg_subset = stm_reg.stm.subset(method="threshold", var="pnt_height", threshold=">5")
         assert stm_reg_subset.dims["space"] == 4
 
+    def test_validate_coords(self):
+        stmat_coords = xr.Dataset(
+            data_vars=dict(
+                data=(
+                    ["space", "time"],
+                    da.arange(5 * 10).reshape((10, 5)),
+                ),
+                x_coor=(["space"], np.arange(10)),
+                y_coor=(["space"], np.arange(10)),
+            ),
+            coords=dict(
+                x=(["space"], np.arange(10)),
+                y=(["space"], np.arange(10)),
+                time=(["time"], np.arange(5)),
+            ),
+        )
+
+        assert _validate_coords(stmat_coords, 'x', 'y') == 1
+        assert _validate_coords(stmat_coords, 'x_coor', 'y_coor') == 2
+        assert _validate_coords(stmat_coords, 'x', 'y_coor') == 2
+
+        with pytest.raises(ValueError):
+            _validate_coords(stmat_coords, 'x_non', 'y_non')
+
 
 class TestAttributes:
     def test_numpoints(self, stmat):
@@ -136,6 +164,13 @@ def test_numpoints(self, stmat):
     def test_numepochss(self, stmat):
         assert stmat.stm.num_epochs == 5
 
+    def test_register_datatype(self, stmat):
+        stmat_with_dtype = stmat.stm.register_datatype("pnt_height", "pntAttrib")
+        assert "pnt_height" in stmat_with_dtype.attrs["pntAttrib"]
+
+    def test_register_datatype_nonexists(self, stmat):
+        with pytest.raises(ValueError):
+            stmat.stm.register_datatype("non_exist", "pntAttrib")
 
 class TestSubset:
     def test_check_missing_dimension(self, stmat_only_point):
@@ -184,7 +219,7 @@ def test_subset_with_polygons_rd(self, stmat_rd, polygon):
     def test_subset_with_multi_polygons(self, stmat, multi_polygon):
         stmat_subset = stmat.stm.subset(method="polygon", polygon=multi_polygon)
         assert stmat_subset.equals(stmat.sel(space=[2, 6]))
-    
+
     def test_subset_with_multi_polygons_file(self, stmat):
         stmat_subset = stmat.stm.subset(method="polygon", polygon=path_multi_polygon)
         assert stmat_subset.equals(stmat.sel(space=[2, 6]))
@@ -228,3 +263,22 @@ def test_enrich_multi_fields_multi_polygon(self, stmat, multi_polygon):
             results = stmat[field].data.compute()
             results = [res for res in results if res is not None]
             assert np.all(results == np.array(multi_polygon[field]))
+
+    def test_enrich_multi_fields_multi_polygon_from_file(self, stmat):
+        multi_polygon = gpd.read_file(path_multi_polygon)
+        fields = multi_polygon.columns[0:2]
+        stmat = stmat.stm.enrich_from_polygon(path_multi_polygon, fields)
+        for field in fields:
+            assert field in stmat.data_vars
+
+            results = stmat[field].data.compute()
+            results = [res for res in results if res is not None]
+            assert np.all(results == np.array(multi_polygon[field]))
+
+    def test_enrich_exetions(self, stmat, multi_polygon):
+        with pytest.raises(NotImplementedError):
+            # int not implemented for polygons
+            stmat = stmat.stm.enrich_from_polygon(999, "field")
+
+        with pytest.raises(ValueError):
+            stmat = stmat.stm.enrich_from_polygon(multi_polygon, "non_exist_field")