diff --git a/pygmt/tests/test_binstats.py b/pygmt/tests/test_binstats.py
index eeaa22020d5..6b77c82f861 100644
--- a/pygmt/tests/test_binstats.py
+++ b/pygmt/tests/test_binstats.py
@@ -43,8 +43,8 @@ def test_binstats_no_outgrid():
         region="g",
     )
     assert temp_grid.dims == ("y", "x")
-    assert temp_grid.gmt.gtype == GridType.CARTESIAN
-    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert temp_grid.gmt.gtype is GridType.CARTESIAN
+    assert temp_grid.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 35971536)
     npt.assert_allclose(temp_grid.min(), 53)
     npt.assert_allclose(temp_grid.median(), 1232714.5)
diff --git a/pygmt/tests/test_datasets_earth_age.py b/pygmt/tests/test_datasets_earth_age.py
index 3407ac0776a..4074fa07004 100644
--- a/pygmt/tests/test_datasets_earth_age.py
+++ b/pygmt/tests/test_datasets_earth_age.py
@@ -19,7 +19,7 @@ def test_earth_age_01d():
     assert data.attrs["units"] == "Myr"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), 0.37, atol=0.01)
@@ -32,7 +32,7 @@ def test_earth_age_01d_with_region():
     """
     data = load_earth_age(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 11.13, atol=0.01)
@@ -46,7 +46,7 @@ def test_earth_age_01m_default_registration():
     """
     data = load_earth_age(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_day.py b/pygmt/tests/test_datasets_earth_day.py
index f04269135f8..35802ff626e 100644
--- a/pygmt/tests/test_datasets_earth_day.py
+++ b/pygmt/tests/test_datasets_earth_day.py
@@ -19,8 +19,8 @@ def test_blue_marble_01d():
     assert data.attrs["description"] == "NASA Day Images"
     assert data.shape == (3, 180, 360)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == GridRegistration.PIXEL
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.PIXEL
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(89.5, -90.5, -1))
     npt.assert_allclose(data.x, np.arange(-179.5, 180.5, 1))
     npt.assert_allclose(data.min(), 10, atol=1)
@@ -34,8 +34,8 @@ def test_blue_marble_01d_with_region():
     data = load_blue_marble(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (3, 10, 20)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == GridRegistration.PIXEL
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.PIXEL
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(4.5, -5.5, -1))
     npt.assert_allclose(data.x, np.arange(-9.5, 10.5, 1))
     npt.assert_allclose(data.min(), 10, atol=1)
diff --git a/pygmt/tests/test_datasets_earth_deflection.py b/pygmt/tests/test_datasets_earth_deflection.py
index a30eab07902..9efa29d7a5a 100644
--- a/pygmt/tests/test_datasets_earth_deflection.py
+++ b/pygmt/tests/test_datasets_earth_deflection.py
@@ -20,7 +20,7 @@ def test_earth_edefl_01d():
     assert data.attrs["units"] == "micro-radians"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -142.64, atol=0.04)
@@ -33,7 +33,7 @@ def test_earth_edefl_01d_with_region():
     """
     data = load_earth_deflection(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -28.92, atol=0.04)
@@ -47,7 +47,7 @@ def test_earth_edefl_01m_default_registration():
     """
     data = load_earth_deflection(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (120, 60)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
@@ -67,7 +67,7 @@ def test_earth_ndefl_01d():
     assert data.attrs["units"] == "micro-radians"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -214.8, atol=0.04)
@@ -82,7 +82,7 @@ def test_earth_ndefl_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5], component="north"
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -48.08, atol=0.04)
@@ -98,7 +98,7 @@ def test_earth_ndefl_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5], component="north"
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_earth_dist.py b/pygmt/tests/test_datasets_earth_dist.py
index 78c2b24c988..63f95751f45 100644
--- a/pygmt/tests/test_datasets_earth_dist.py
+++ b/pygmt/tests/test_datasets_earth_dist.py
@@ -18,7 +18,7 @@ def test_earth_dist_01d():
     assert data.attrs["units"] == "kilometers"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -2655.7, atol=0.01)
@@ -31,7 +31,7 @@ def test_earth_dist_01d_with_region():
     """
     data = load_earth_dist(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1081.94, atol=0.01)
@@ -45,7 +45,7 @@ def test_earth_dist_01m_default_registration():
     """
     data = load_earth_dist(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_free_air_anomaly.py b/pygmt/tests/test_datasets_earth_free_air_anomaly.py
index a60c1fec2e6..da8ada3ed9f 100644
--- a/pygmt/tests/test_datasets_earth_free_air_anomaly.py
+++ b/pygmt/tests/test_datasets_earth_free_air_anomaly.py
@@ -19,7 +19,7 @@ def test_earth_faa_01d():
     assert data.attrs["units"] == "mGal"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -188.85, atol=0.025)
@@ -32,7 +32,7 @@ def test_earth_faa_01d_with_region():
     """
     data = load_earth_free_air_anomaly(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -36.125, atol=0.025)
@@ -46,7 +46,7 @@ def test_earth_faa_01m_default_registration():
     """
     data = load_earth_free_air_anomaly(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (120, 60)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
@@ -66,7 +66,7 @@ def test_earth_faaerror_01d():
     assert data.attrs["units"] == "mGal"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), 0.0, atol=0.04)
@@ -81,7 +81,7 @@ def test_earth_faaerror_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5], uncertainty=True
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 0.72, atol=0.04)
@@ -97,7 +97,7 @@ def test_earth_faaerror_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5], uncertainty=True
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_earth_geoid.py b/pygmt/tests/test_datasets_earth_geoid.py
index bb7f09102d9..9919164a573 100644
--- a/pygmt/tests/test_datasets_earth_geoid.py
+++ b/pygmt/tests/test_datasets_earth_geoid.py
@@ -19,7 +19,7 @@ def test_earth_geoid_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -106.06, atol=0.01)
@@ -32,7 +32,7 @@ def test_earth_geoid_01d_with_region():
     """
     data = load_earth_geoid(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 5.57, atol=0.01)
@@ -46,7 +46,7 @@ def test_earth_geoid_01m_default_registration():
     """
     data = load_earth_geoid(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_magnetic_anomaly.py b/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
index e3e8757bcf6..e2ab2e68b09 100644
--- a/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
+++ b/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
@@ -21,7 +21,7 @@ def test_earth_mag_01d():
     assert data.attrs["units"] == "nT"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -336.2, atol=0.2)
@@ -34,7 +34,7 @@ def test_earth_mag_01d_with_region():
     """
     data = load_earth_magnetic_anomaly(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -54.4, atol=0.2)
@@ -48,7 +48,7 @@ def test_earth_mag_02m_default_registration():
     """
     data = load_earth_magnetic_anomaly(resolution="02m", region=[-10, -9, 3, 5])
     assert data.shape == (60, 30)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.016666667)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.983333333)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.98333333)
@@ -68,7 +68,7 @@ def test_earth_mag4km_01d():
     assert data.attrs["units"] == "nT"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -436.8, atol=0.2)
@@ -103,7 +103,7 @@ def test_earth_mag4km_02m_default_registration():
         data_source="emag2_4km",
     )
     assert data.shape == (60, 90)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 4.01666667)
     npt.assert_allclose(data.coords["lat"].data.max(), 5.98333333)
     npt.assert_allclose(data.coords["lon"].data.min(), -114.98333333)
@@ -155,7 +155,7 @@ def test_earth_mag_03m_wdmam_with_region():
     data = load_earth_magnetic_anomaly(
         resolution="03m", region=[10, 13, -60, -58], data_source="wdmam"
     )
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.shape == (41, 61)
     assert data.lat.min() == -60
     assert data.lat.max() == -58
diff --git a/pygmt/tests/test_datasets_earth_mask.py b/pygmt/tests/test_datasets_earth_mask.py
index 3e33ab1172b..fec4d124269 100644
--- a/pygmt/tests/test_datasets_earth_mask.py
+++ b/pygmt/tests/test_datasets_earth_mask.py
@@ -17,8 +17,8 @@ def test_earth_mask_01d():
     assert data.attrs["description"] == "GSHHG Earth mask"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.GRIDLINE
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     assert data.dtype == "int8"
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
@@ -33,8 +33,8 @@ def test_earth_mask_01d_with_region():
     """
     data = load_earth_mask(resolution="01d", region=[-7, 4, 13, 19])
     assert data.shape == (7, 12)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.GRIDLINE
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     assert data.dtype == "int8"
     npt.assert_allclose(data.lat, np.arange(13, 20, 1))
     npt.assert_allclose(data.lon, np.arange(-7, 5, 1))
diff --git a/pygmt/tests/test_datasets_earth_mean_sea_surface.py b/pygmt/tests/test_datasets_earth_mean_sea_surface.py
index 7206cbf911f..0f4679b08cd 100644
--- a/pygmt/tests/test_datasets_earth_mean_sea_surface.py
+++ b/pygmt/tests/test_datasets_earth_mean_sea_surface.py
@@ -18,7 +18,7 @@ def test_earth_mss_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -104.71, atol=0.01)
@@ -31,7 +31,7 @@ def test_earth_mss_01d_with_region():
     """
     data = load_earth_mean_sea_surface(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 6.53, atol=0.01)
@@ -45,7 +45,7 @@ def test_earth_mss_01m_default_registration():
     """
     data = load_earth_mean_sea_surface(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_night.py b/pygmt/tests/test_datasets_earth_night.py
index 0865feaa1e8..91f8fb865ad 100644
--- a/pygmt/tests/test_datasets_earth_night.py
+++ b/pygmt/tests/test_datasets_earth_night.py
@@ -19,8 +19,8 @@ def test_black_marble_01d():
     assert data.attrs["description"] == "NASA Night Images"
     assert data.shape == (3, 180, 360)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == GridRegistration.PIXEL
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.PIXEL
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(89.5, -90.5, -1))
     npt.assert_allclose(data.x, np.arange(-179.5, 180.5, 1))
     npt.assert_allclose(data.min(), 3, atol=1)
@@ -34,8 +34,8 @@ def test_black_marble_01d_with_region():
     data = load_black_marble(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (3, 10, 20)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == GridRegistration.PIXEL
-    assert data.gmt.gtype == GridType.GEOGRAPHIC
+    assert data.gmt.registration is GridRegistration.PIXEL
+    assert data.gmt.gtype is GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(4.5, -5.5, -1))
     npt.assert_allclose(data.x, np.arange(-9.5, 10.5, 1))
     npt.assert_allclose(data.min(), 3, atol=1)
diff --git a/pygmt/tests/test_datasets_earth_relief.py b/pygmt/tests/test_datasets_earth_relief.py
index d94a9cc336c..5d69d0d147f 100644
--- a/pygmt/tests/test_datasets_earth_relief.py
+++ b/pygmt/tests/test_datasets_earth_relief.py
@@ -26,7 +26,7 @@ def test_earth_relief_01d_igpp_synbath(data_source):
     assert data.attrs["vertical_datum"] == "EGM96"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7174.0, atol=0.5)
@@ -46,7 +46,7 @@ def test_earth_relief_01d_gebco(data_source):
     assert data.attrs["vertical_datum"] == "EGM96"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7169.0, atol=1.0)
@@ -63,7 +63,7 @@ def test_earth_relief_01d_with_region_srtm():
         data_source="igpp",
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5137.0, atol=0.5)
@@ -80,7 +80,7 @@ def test_earth_relief_01d_with_region_gebco():
         data_source="gebco",
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5118.0, atol=1.0)
@@ -93,7 +93,7 @@ def test_earth_relief_30m():
     """
     data = load_earth_relief(resolution="30m")
     assert data.shape == (361, 721)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 90.5, 0.5))
     npt.assert_allclose(data.lon, np.arange(-180, 180.5, 0.5))
     npt.assert_allclose(data.min(), -8279.5, atol=0.5)
@@ -111,7 +111,7 @@ def test_earth_gebcosi_15m_with_region():
         data_source="gebcosi",
     )
     assert data.shape == (16, 8)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.lat, np.arange(-87.875, -84, 0.25))
     npt.assert_allclose(data.lon, np.arange(85.125, 87, 0.25))
     npt.assert_allclose(data.min(), -492, atol=1.0)
@@ -184,7 +184,7 @@ def test_earth_relief_15s_default_registration():
     """
     data = load_earth_relief(resolution="15s", region=[-10, -9.5, 4, 5])
     assert data.shape == (240, 120)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 4.002083)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.997917)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.997917)
@@ -205,7 +205,7 @@ def test_earth_relief_03s_default_registration():
     """
     data = load_earth_relief(resolution="03s", region=[-10, -9.8, 4.9, 5])
     assert data.shape == (121, 241)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.coords["lat"].data.min(), 4.9)
     npt.assert_allclose(data.coords["lat"].data.max(), 5)
     npt.assert_allclose(data.coords["lon"].data.min(), -10)
diff --git a/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py b/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
index 9851f8ceea9..31876457570 100644
--- a/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
+++ b/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
@@ -19,7 +19,7 @@ def test_earth_vertical_gravity_gradient_01d():
     assert data.attrs["units"] == "Eotvos"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -40.1875, atol=1 / 32)
@@ -35,7 +35,7 @@ def test_earth_vertical_gravity_gradient_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5]
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5.34375, atol=1 / 32)
@@ -51,7 +51,7 @@ def test_earth_vertical_gravity_gradient_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5]
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.registration is GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_load_remote_datasets.py b/pygmt/tests/test_datasets_load_remote_datasets.py
index db755890a26..1d497101e67 100644
--- a/pygmt/tests/test_datasets_load_remote_datasets.py
+++ b/pygmt/tests/test_datasets_load_remote_datasets.py
@@ -31,7 +31,7 @@ def test_load_remote_dataset_benchmark_with_region():
     assert data.attrs["long_name"] == "ages (Myr)"
     assert data.attrs["units"] == "Myr"
     assert data.attrs["horizontal_datum"] == "WGS84"
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.shape == (11, 21)
     # Can't access the cpt attribute using virtual files
     # assert data.attrs["cpt"] == "@earth_age.cpt"
diff --git a/pygmt/tests/test_datasets_mars_relief.py b/pygmt/tests/test_datasets_mars_relief.py
index e60265b6044..2f3b81e942a 100644
--- a/pygmt/tests/test_datasets_mars_relief.py
+++ b/pygmt/tests/test_datasets_mars_relief.py
@@ -18,7 +18,7 @@ def test_mars_relief_01d():
     assert data.attrs["description"] == "NASA Mars (MOLA) relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7421.0, atol=0.5)
@@ -31,7 +31,7 @@ def test_mars_relief_01d_with_region():
     """
     data = load_mars_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -2502.0, atol=0.5)
@@ -45,7 +45,7 @@ def test_mars_relief_01m_default_registration():
     """
     data = load_mars_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_mean_dynamic_topography.py b/pygmt/tests/test_datasets_mean_dynamic_topography.py
index c373b727e79..f14f2b6d4f1 100644
--- a/pygmt/tests/test_datasets_mean_dynamic_topography.py
+++ b/pygmt/tests/test_datasets_mean_dynamic_topography.py
@@ -18,7 +18,7 @@ def test_earth_mdt_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -1.4668, atol=0.0001)
@@ -31,7 +31,7 @@ def test_earth_mdt_01d_with_region():
     """
     data = load_earth_mean_dynamic_topography(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 0.346, atol=0.0001)
@@ -45,7 +45,7 @@ def test_earth_mdt_07m_default_registration():
     """
     data = load_earth_mean_dynamic_topography(resolution="07m", region=[-10, -9, 3, 5])
     assert data.shape == (17, 9)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_mercury_relief.py b/pygmt/tests/test_datasets_mercury_relief.py
index a81af88066e..b9ba52c9379 100644
--- a/pygmt/tests/test_datasets_mercury_relief.py
+++ b/pygmt/tests/test_datasets_mercury_relief.py
@@ -18,7 +18,7 @@ def test_mercury_relief_01d():
     assert data.attrs["description"] == "USGS Mercury relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -5103.5, atol=0.5)
@@ -31,7 +31,7 @@ def test_mercury_relief_01d_with_region():
     """
     data = load_mercury_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -327.0, atol=0.5)
@@ -45,7 +45,7 @@ def test_mercury_relief_01m_default_registration():
     """
     data = load_mercury_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_moon_relief.py b/pygmt/tests/test_datasets_moon_relief.py
index 50d20e910ee..477ff4e0e8f 100644
--- a/pygmt/tests/test_datasets_moon_relief.py
+++ b/pygmt/tests/test_datasets_moon_relief.py
@@ -18,7 +18,7 @@ def test_moon_relief_01d():
     assert data.attrs["description"] == "USGS Moon (LOLA) relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7669.0, atol=0.5)
@@ -31,7 +31,7 @@ def test_moon_relief_01d_with_region():
     """
     data = load_moon_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1122.0, atol=0.5)
@@ -45,7 +45,7 @@ def test_moon_relief_01m_default_registration():
     """
     data = load_moon_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_pluto_relief.py b/pygmt/tests/test_datasets_pluto_relief.py
index dd6ac599ab4..d024c7314de 100644
--- a/pygmt/tests/test_datasets_pluto_relief.py
+++ b/pygmt/tests/test_datasets_pluto_relief.py
@@ -18,7 +18,7 @@ def test_pluto_relief_01d():
     assert data.attrs["description"] == "USGS Pluto relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -3021.0, atol=0.25)
@@ -31,7 +31,7 @@ def test_pluto_relief_01d_with_region():
     """
     data = load_pluto_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1319.25, atol=0.25)
@@ -45,7 +45,7 @@ def test_pluto_relief_01m_default_registration():
     """
     data = load_pluto_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_venus_relief.py b/pygmt/tests/test_datasets_venus_relief.py
index 2790ad247e7..6cbe5123bb7 100644
--- a/pygmt/tests/test_datasets_venus_relief.py
+++ b/pygmt/tests/test_datasets_venus_relief.py
@@ -18,7 +18,7 @@ def test_venus_relief_01d():
     assert data.attrs["description"] == "NASA Magellan Venus relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -2069.0, atol=0.5)
@@ -31,7 +31,7 @@ def test_venus_relief_01d_with_region():
     """
     data = load_venus_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1244.0, atol=0.5)
@@ -45,7 +45,7 @@ def test_venus_relief_01m_default_registration():
     """
     data = load_venus_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.registration is GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_dimfilter.py b/pygmt/tests/test_dimfilter.py
index eae188abb09..ca1f5e120e1 100644
--- a/pygmt/tests/test_dimfilter.py
+++ b/pygmt/tests/test_dimfilter.py
@@ -70,8 +70,8 @@ def test_dimfilter_no_outgrid(grid, expected_grid):
         grid=grid, filter="m600", distance=4, sectors="l6", region=[-55, -51, -24, -19]
     )
     assert result.dims == ("lat", "lon")
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_grdclip.py b/pygmt/tests/test_grdclip.py
index 796247919c1..818488914a8 100644
--- a/pygmt/tests/test_grdclip.py
+++ b/pygmt/tests/test_grdclip.py
@@ -56,8 +56,8 @@ def test_grdclip_outgrid(grid, expected_grid):
         assert Path(tmpfile.name).stat().st_size > 0  # check that outgrid exists
         temp_grid = xr.load_dataarray(tmpfile.name, engine="gmt", raster_kind="grid")
         assert temp_grid.dims == ("lat", "lon")
-        assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-        assert temp_grid.gmt.registration == GridRegistration.PIXEL
+        assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+        assert temp_grid.gmt.registration is GridRegistration.PIXEL
         xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
@@ -70,8 +70,8 @@ def test_grdclip_no_outgrid(grid, expected_grid):
         grid=grid, below=[550, -1000], above=[700, 1000], region=[-53, -49, -19, -16]
     )
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-    assert temp_grid.gmt.registration == GridRegistration.PIXEL
+    assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration is GridRegistration.PIXEL
     xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_grdfill.py b/pygmt/tests/test_grdfill.py
index 2f6af387679..c15b8464b7e 100644
--- a/pygmt/tests/test_grdfill.py
+++ b/pygmt/tests/test_grdfill.py
@@ -65,8 +65,8 @@ def test_grdfill_dataarray_out(grid, expected_grid):
     result = grdfill(grid=grid, constantfill=20)
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
@@ -80,8 +80,8 @@ def test_grdfill_asymmetric_pad(grid, expected_grid):
     result = grdfill(grid=grid, constantfill=20, region=[-55, -50, -24, -16])
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(
         a=result, b=expected_grid.sel(lon=slice(-55, -50), lat=slice(-24, -16))
diff --git a/pygmt/tests/test_grdfilter.py b/pygmt/tests/test_grdfilter.py
index 9e06523c8b9..463a3d5c3ea 100644
--- a/pygmt/tests/test_grdfilter.py
+++ b/pygmt/tests/test_grdfilter.py
@@ -51,8 +51,8 @@ def test_grdfilter_dataarray_in_dataarray_out(grid, expected_grid):
     )
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdgradient.py b/pygmt/tests/test_grdgradient.py
index 8f4b34a8b29..5749b237aea 100644
--- a/pygmt/tests/test_grdgradient.py
+++ b/pygmt/tests/test_grdgradient.py
@@ -67,8 +67,8 @@ def test_grdgradient_no_outgrid(grid, expected_grid):
     )
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdhisteq.py b/pygmt/tests/test_grdhisteq.py
index 9be0a10d08b..be1ccb7db95 100644
--- a/pygmt/tests/test_grdhisteq.py
+++ b/pygmt/tests/test_grdhisteq.py
@@ -79,8 +79,8 @@ def test_equalize_grid_no_outgrid(grid, expected_grid, region):
     temp_grid = grdhisteq.equalize_grid(
         grid=grid, divisions=2, region=region, outgrid=None
     )
-    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-    assert temp_grid.gmt.registration == GridRegistration.PIXEL
+    assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration is GridRegistration.PIXEL
     xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_grdimage.py b/pygmt/tests/test_grdimage.py
index 9f11e6a2923..f92dbeb3587 100644
--- a/pygmt/tests/test_grdimage.py
+++ b/pygmt/tests/test_grdimage.py
@@ -172,7 +172,7 @@ def test_grdimage_over_dateline(xrgrid):
     See also https://github.com/GenericMappingTools/pygmt/issues/375.
     """
     fig = Figure()
-    assert xrgrid.gmt.registration == GridRegistration.GRIDLINE
+    assert xrgrid.gmt.registration is GridRegistration.GRIDLINE
     xrgrid.gmt.gtype = GridType.GEOGRAPHIC
     fig.grdimage(grid=xrgrid, region="g", projection="A0/0/1c")
     return fig
@@ -190,8 +190,8 @@ def test_grdimage_global_subset(grid_360):
     """
     # Get a slice of South America and Africa only (lat=-90:31, lon=-180:41)
     sliced_grid = grid_360[0:121, 0:221]
-    assert sliced_grid.gmt.registration == GridRegistration.GRIDLINE
-    assert sliced_grid.gmt.gtype == GridType.CARTESIAN
+    assert sliced_grid.gmt.registration is GridRegistration.GRIDLINE
+    assert sliced_grid.gmt.gtype is GridType.CARTESIAN
 
     fig = Figure()
     fig.grdimage(
diff --git a/pygmt/tests/test_grdlandmask.py b/pygmt/tests/test_grdlandmask.py
index 36dbb64a0b8..21b45d8d8c5 100644
--- a/pygmt/tests/test_grdlandmask.py
+++ b/pygmt/tests/test_grdlandmask.py
@@ -54,8 +54,8 @@ def test_grdlandmask_no_outgrid(expected_grid):
     result = grdlandmask(spacing=1, region=[125, 130, 30, 35], cores=2)
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.GRIDLINE
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.GRIDLINE
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdproject.py b/pygmt/tests/test_grdproject.py
index 9f95cd14f92..8d4a1f70a21 100644
--- a/pygmt/tests/test_grdproject.py
+++ b/pygmt/tests/test_grdproject.py
@@ -71,12 +71,12 @@ def test_grdproject_no_outgrid(grid, projection, expected_grid):
 
     Also check that providing the projection as an EPSG code or PROJ4 string works.
     """
-    assert grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert grid.gmt.gtype is GridType.GEOGRAPHIC
     result = grdproject(
         grid=grid, projection=projection, spacing=3, region=[-53, -51, -20, -17]
     )
-    assert result.gmt.gtype == GridType.CARTESIAN
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.CARTESIAN
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdsample.py b/pygmt/tests/test_grdsample.py
index 9c8a0d229c8..4b768ef22eb 100644
--- a/pygmt/tests/test_grdsample.py
+++ b/pygmt/tests/test_grdsample.py
@@ -79,8 +79,8 @@ def test_grdsample_dataarray_out(grid, expected_grid, region, spacing):
     result = grdsample(grid=grid, spacing=spacing, region=region, cores=2)
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == GridType.GEOGRAPHIC
-    assert result.gmt.registration == GridRegistration.PIXEL
+    assert result.gmt.gtype is GridType.GEOGRAPHIC
+    assert result.gmt.registration is GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
@@ -89,8 +89,8 @@ def test_grdsample_registration_changes(grid):
     """
     Test grdsample with no set outgrid and applying registration changes.
     """
-    assert grid.gmt.registration == GridRegistration.PIXEL
+    assert grid.gmt.registration is GridRegistration.PIXEL
     translated_grid = grdsample(grid=grid, translate=True)
-    assert translated_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert translated_grid.gmt.registration is GridRegistration.GRIDLINE
     registration_grid = grdsample(grid=translated_grid, registration="p")
-    assert registration_grid.gmt.registration == GridRegistration.PIXEL
+    assert registration_grid.gmt.registration is GridRegistration.PIXEL
diff --git a/pygmt/tests/test_io.py b/pygmt/tests/test_io.py
index f797245632a..24829ff2ae0 100644
--- a/pygmt/tests/test_io.py
+++ b/pygmt/tests/test_io.py
@@ -28,8 +28,8 @@ def test_io_load_dataarray():
         with pytest.warns(FutureWarning):
             dataarray = load_dataarray(tmpfile.name)
 
-        assert dataarray.gmt.gtype == GridType.CARTESIAN
-        assert dataarray.gmt.registration == GridRegistration.PIXEL
+        assert dataarray.gmt.gtype is GridType.CARTESIAN
+        assert dataarray.gmt.registration is GridRegistration.PIXEL
         # this would fail if we used xr.open_dataarray instead of load_dataarray
         dataarray.to_netcdf(tmpfile.name)
 
diff --git a/pygmt/tests/test_nearneighbor.py b/pygmt/tests/test_nearneighbor.py
index 38e48082024..49522a4a171 100644
--- a/pygmt/tests/test_nearneighbor.py
+++ b/pygmt/tests/test_nearneighbor.py
@@ -33,8 +33,8 @@ def test_nearneighbor_input_data(array_func, ship_data):
         data=data, spacing="5m", region=[245, 255, 20, 30], search_radius="10m"
     )
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == GridRegistration.GRIDLINE
-    assert output.gmt.gtype == GridType.GEOGRAPHIC
+    assert output.gmt.registration is GridRegistration.GRIDLINE
+    assert output.gmt.gtype is GridType.GEOGRAPHIC
     assert output.shape == (121, 121)
     npt.assert_allclose(output.mean(), -2378.2385)
 
diff --git a/pygmt/tests/test_sph2grd.py b/pygmt/tests/test_sph2grd.py
index e3c71293621..e68008b23dc 100644
--- a/pygmt/tests/test_sph2grd.py
+++ b/pygmt/tests/test_sph2grd.py
@@ -30,8 +30,8 @@ def test_sph2grd_no_outgrid():
     """
     temp_grid = sph2grd(data="@EGM96_to_36.txt", spacing=1, region="g", cores=2)
     assert temp_grid.dims == ("y", "x")
-    assert temp_grid.gmt.gtype == GridType.CARTESIAN
-    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert temp_grid.gmt.gtype is GridType.CARTESIAN
+    assert temp_grid.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 0.00021961, rtol=1e-4)
     npt.assert_allclose(temp_grid.min(), -0.0004326, rtol=1e-4)
     npt.assert_allclose(temp_grid.median(), -0.00010894, rtol=1e-4)
diff --git a/pygmt/tests/test_sphdistance.py b/pygmt/tests/test_sphdistance.py
index ac3701fb0c3..f96f14530e5 100644
--- a/pygmt/tests/test_sphdistance.py
+++ b/pygmt/tests/test_sphdistance.py
@@ -30,8 +30,8 @@ def test_sphdistance_xy_inputs():
     x = [85.5, 82.3, 85.8, 86.5]
     temp_grid = sphdistance(x=x, y=y, spacing=[1, 2], region=[82, 87, 22, 24])
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 232977.546875)
     npt.assert_allclose(temp_grid.min(), 0)
     npt.assert_allclose(temp_grid.median(), 0)
@@ -57,8 +57,8 @@ def test_sphdistance_no_outgrid(array):
     """
     temp_grid = sphdistance(data=array, spacing=[1, 2], region=[82, 87, 22, 24])
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 232977.546875)
     npt.assert_allclose(temp_grid.min(), 0)
     npt.assert_allclose(temp_grid.median(), 0)
diff --git a/pygmt/tests/test_sphinterpolate.py b/pygmt/tests/test_sphinterpolate.py
index ab394c5f462..e2abcd3114e 100644
--- a/pygmt/tests/test_sphinterpolate.py
+++ b/pygmt/tests/test_sphinterpolate.py
@@ -39,8 +39,8 @@ def test_sphinterpolate_no_outgrid(mars):
     """
     temp_grid = sphinterpolate(data=mars, spacing=1, region="g")
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
-    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert temp_grid.gmt.gtype is GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration is GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 14628.144)
     npt.assert_allclose(temp_grid.min(), -6908.1987)
     npt.assert_allclose(temp_grid.median(), 118.96849)
diff --git a/pygmt/tests/test_surface.py b/pygmt/tests/test_surface.py
index 2b0c01066db..ab075a045ab 100644
--- a/pygmt/tests/test_surface.py
+++ b/pygmt/tests/test_surface.py
@@ -73,8 +73,8 @@ def check_values(grid, expected_grid):
     Check the attributes and values of the DataArray returned by surface.
     """
     assert isinstance(grid, xr.DataArray)
-    assert grid.gmt.registration == GridRegistration.GRIDLINE
-    assert grid.gmt.gtype == GridType.CARTESIAN
+    assert grid.gmt.registration is GridRegistration.GRIDLINE
+    assert grid.gmt.gtype is GridType.CARTESIAN
     xr.testing.assert_allclose(a=grid, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_triangulate.py b/pygmt/tests/test_triangulate.py
index b46d214effa..88f945a6c1d 100644
--- a/pygmt/tests/test_triangulate.py
+++ b/pygmt/tests/test_triangulate.py
@@ -140,8 +140,8 @@ def test_regular_grid_no_outgrid(dataframe, expected_grid):
     data = dataframe.to_numpy()
     output = triangulate.regular_grid(data=data, spacing=1, region=[2, 4, 5, 6])
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == GridRegistration.GRIDLINE
-    assert output.gmt.gtype == GridType.CARTESIAN
+    assert output.gmt.registration is GridRegistration.GRIDLINE
+    assert output.gmt.gtype is GridType.CARTESIAN
     xr.testing.assert_allclose(a=output, b=expected_grid)
 
 
@@ -158,6 +158,6 @@ def test_regular_grid_with_outgrid_param(dataframe, expected_grid):
         assert Path(tmpfile.name).stat().st_size > 0  # check that outgrid exists
         grid = xr.load_dataarray(tmpfile.name, engine="gmt", raster_kind="grid")
         assert isinstance(grid, xr.DataArray)
-        assert grid.gmt.registration == GridRegistration.GRIDLINE
-        assert grid.gmt.gtype == GridType.CARTESIAN
+        assert grid.gmt.registration is GridRegistration.GRIDLINE
+        assert grid.gmt.gtype is GridType.CARTESIAN
         xr.testing.assert_allclose(a=grid, b=expected_grid)
diff --git a/pygmt/tests/test_xarray_accessor.py b/pygmt/tests/test_xarray_accessor.py
index 4967d37e6ce..11b184110f6 100644
--- a/pygmt/tests/test_xarray_accessor.py
+++ b/pygmt/tests/test_xarray_accessor.py
@@ -24,8 +24,8 @@ def test_xarray_accessor_gridline_cartesian():
     Cartesian, gridline-registered grid.
     """
     grid = xr.load_dataarray("@test.dat.nc", engine="gmt", raster_kind="grid")
-    assert grid.gmt.registration == GridRegistration.GRIDLINE
-    assert grid.gmt.gtype == GridType.CARTESIAN
+    assert grid.gmt.registration is GridRegistration.GRIDLINE
+    assert grid.gmt.gtype is GridType.CARTESIAN
 
 
 def test_xarray_accessor_pixel_geographic():
@@ -34,8 +34,8 @@ def test_xarray_accessor_pixel_geographic():
     geographic, pixel-registered grid.
     """
     grid = xr.load_dataarray("@earth_relief_01d_p", engine="gmt", raster_kind="grid")
-    assert grid.gmt.registration == GridRegistration.PIXEL
-    assert grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert grid.gmt.registration is GridRegistration.PIXEL
+    assert grid.gmt.gtype is GridType.GEOGRAPHIC
 
 
 def test_xarray_accessor_set_registration():
@@ -44,23 +44,23 @@ def test_xarray_accessor_set_registration():
     """
     grid = xr.DataArray(data=[[0.1, 0.2], [0.3, 0.4]])
     # Default to gridline registration
-    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
+    assert grid.gmt.registration is GridRegistration.GRIDLINE == 0
 
     # Set the registration to pixel
     grid.gmt.registration = GridRegistration.PIXEL
-    assert grid.gmt.registration == GridRegistration.PIXEL == 1
+    assert grid.gmt.registration is GridRegistration.PIXEL == 1
 
     # Set the registration to gridline
     grid.gmt.registration = GridRegistration.GRIDLINE
-    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
+    assert grid.gmt.registration is GridRegistration.GRIDLINE == 0
 
     # Set the registration to pixel but using a numerical value
     grid.gmt.registration = 1
-    assert grid.gmt.registration == GridRegistration.PIXEL == 1
+    assert grid.gmt.registration is GridRegistration.PIXEL == 1
 
     # Set the registration to gridline but using a numerical value
     grid.gmt.registration = 0
-    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
+    assert grid.gmt.registration is GridRegistration.GRIDLINE == 0
 
 
 @pytest.mark.benchmark
@@ -69,23 +69,23 @@ def test_xarray_accessor_set_gtype():
     Check that we can set the gtype of a grid.
     """
     grid = xr.DataArray(data=[[0.1, 0.2], [0.3, 0.4]])
-    assert grid.gmt.gtype == GridType.CARTESIAN == 0  # Default gtype
+    assert grid.gmt.gtype is GridType.CARTESIAN == 0  # Default gtype
 
     # Set the gtype to geographic
     grid.gmt.gtype = GridType.GEOGRAPHIC
-    assert grid.gmt.gtype == GridType.GEOGRAPHIC == 1
+    assert grid.gmt.gtype is GridType.GEOGRAPHIC == 1
 
     # Set the gtype to Cartesian
     grid.gmt.gtype = GridType.CARTESIAN
-    assert grid.gmt.gtype == GridType.CARTESIAN == 0
+    assert grid.gmt.gtype is GridType.CARTESIAN == 0
 
     # Set the gtype to geographic but using a numerical value
     grid.gmt.gtype = 1
-    assert grid.gmt.gtype == GridType.GEOGRAPHIC == 1
+    assert grid.gmt.gtype is GridType.GEOGRAPHIC == 1
 
     # Set the gtype to Cartesian but using a numerical value
     grid.gmt.gtype = 0
-    assert grid.gmt.gtype == GridType.CARTESIAN == 0
+    assert grid.gmt.gtype is GridType.CARTESIAN == 0
 
 
 def test_xarray_accessor_set_invalid_registration_and_gtype():
@@ -126,8 +126,8 @@ def test_xarray_accessor_sliced_datacube():
         with xr.open_dataset(fname, engine="netcdf4") as dataset:
             grid = dataset.sel(level=500, month=1, drop=True).z
 
-        assert grid.gmt.registration == GridRegistration.GRIDLINE
-        assert grid.gmt.gtype == GridType.GEOGRAPHIC
+        assert grid.gmt.registration is GridRegistration.GRIDLINE
+        assert grid.gmt.gtype is GridType.GEOGRAPHIC
     finally:
         Path(fname).unlink()
 
@@ -142,19 +142,19 @@ def test_xarray_accessor_grid_source_file_not_exist():
         resolution="05m", region=[0, 5, -5, 5], registration="pixel"
     )
     # Registration and gtype are correct.
-    assert grid.gmt.registration == GridRegistration.PIXEL
-    assert grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert grid.gmt.registration is GridRegistration.PIXEL
+    assert grid.gmt.gtype is GridType.GEOGRAPHIC
     # The source grid file is undefined.
     assert grid.encoding.get("source") is None
 
     # For a sliced grid, fallback to default registration and gtype, because the source
     # grid file doesn't exist.
     sliced_grid = grid[1:3, 1:3]
-    assert sliced_grid.gmt.registration == GridRegistration.GRIDLINE
-    assert sliced_grid.gmt.gtype == GridType.CARTESIAN
+    assert sliced_grid.gmt.registration is GridRegistration.GRIDLINE
+    assert sliced_grid.gmt.gtype is GridType.CARTESIAN
 
     # Still possible to manually set registration and gtype.
     sliced_grid.gmt.registration = GridRegistration.PIXEL
     sliced_grid.gmt.gtype = GridType.GEOGRAPHIC
-    assert sliced_grid.gmt.registration == GridRegistration.PIXEL
-    assert sliced_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert sliced_grid.gmt.registration is GridRegistration.PIXEL
+    assert sliced_grid.gmt.gtype is GridType.GEOGRAPHIC
diff --git a/pygmt/tests/test_xarray_backend.py b/pygmt/tests/test_xarray_backend.py
index 70f469914d7..4704bea9bf0 100644
--- a/pygmt/tests/test_xarray_backend.py
+++ b/pygmt/tests/test_xarray_backend.py
@@ -32,8 +32,8 @@ def test_xarray_backend_load_dataarray():
 
         dataarray = xr.load_dataarray(tmpfile.name, engine="gmt", raster_kind="grid")
 
-        assert dataarray.gmt.gtype == GridType.CARTESIAN
-        assert dataarray.gmt.registration == GridRegistration.PIXEL
+        assert dataarray.gmt.gtype is GridType.CARTESIAN
+        assert dataarray.gmt.registration is GridRegistration.PIXEL
         # ensure data array can be saved back to a NetCDF file
         dataarray.to_netcdf(tmpfile.name)
 
@@ -48,8 +48,8 @@ def test_xarray_backend_gmt_open_nc_grid():
     ) as da:
         assert da.sizes == {"lat": 14, "lon": 8}
         assert da.dtype == "float32"
-        assert da.gmt.gtype == GridType.GEOGRAPHIC
-        assert da.gmt.registration == GridRegistration.PIXEL
+        assert da.gmt.gtype is GridType.GEOGRAPHIC
+        assert da.gmt.registration is GridRegistration.PIXEL
 
 
 def test_xarray_backend_gmt_open_tif_image():
@@ -60,8 +60,8 @@ def test_xarray_backend_gmt_open_tif_image():
     with xr.open_dataarray("@earth_day_01d", engine="gmt", raster_kind="image") as da:
         assert da.sizes == {"band": 3, "y": 180, "x": 360}
         assert da.dtype == "uint8"
-        assert da.gmt.gtype == GridType.GEOGRAPHIC
-        assert da.gmt.registration == GridRegistration.PIXEL
+        assert da.gmt.gtype is GridType.GEOGRAPHIC
+        assert da.gmt.registration is GridRegistration.PIXEL
 
 
 def test_xarray_backend_gmt_load_grd_grid():
@@ -77,8 +77,8 @@ def test_xarray_backend_gmt_load_grd_grid():
     npt.assert_allclose(da.min(), -4929.5)
     assert da.sizes == {"lat": 31, "lon": 31}
     assert da.dtype == "float32"
-    assert da.gmt.gtype == GridType.GEOGRAPHIC
-    assert da.gmt.registration == GridRegistration.GRIDLINE
+    assert da.gmt.gtype is GridType.GEOGRAPHIC
+    assert da.gmt.registration is GridRegistration.GRIDLINE
 
 
 def test_xarray_backend_gmt_read_invalid_kind():
diff --git a/pygmt/tests/test_xyz2grd.py b/pygmt/tests/test_xyz2grd.py
index 456174beaab..9f70c73cf8c 100644
--- a/pygmt/tests/test_xyz2grd.py
+++ b/pygmt/tests/test_xyz2grd.py
@@ -49,8 +49,8 @@ def test_xyz2grd_input_array(array_func, ship_data, expected_grid):
     """
     output = xyz2grd(data=array_func(ship_data), spacing=5, region=[245, 255, 20, 30])
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == GridRegistration.GRIDLINE
-    assert output.gmt.gtype == GridType.CARTESIAN
+    assert output.gmt.registration is GridRegistration.GRIDLINE
+    assert output.gmt.gtype is GridType.CARTESIAN
     xr.testing.assert_allclose(a=output, b=expected_grid)
 
 
diff --git a/pygmt/xarray/accessor.py b/pygmt/xarray/accessor.py
index d0891076d2a..68162151853 100644
--- a/pygmt/xarray/accessor.py
+++ b/pygmt/xarray/accessor.py
@@ -137,9 +137,11 @@ def __init__(self, xarray_obj: xr.DataArray):
         # two columns of the shortened summary information of grdinfo.
         if (_source := self._obj.encoding.get("source")) and Path(_source).exists():
             with contextlib.suppress(ValueError):
-                self._registration, self._gtype = map(  # type: ignore[assignment]
+                _registration, _gtype = map(
                     int, grdinfo(_source, per_column="n").split()[-2:]
                 )
+            self._registration = GridRegistration(_registration)
+            self._gtype = GridType(_gtype)
 
     @property
     def registration(self) -> GridRegistration: