Use xarray.testing rather than pygmt.grdinfo in grdfill tests (#1677)

* remove grdinfo from grdfill tests

* convert testing to use xarray testing

* change region in sample grid to use land coordinates over smaller region

Author: willschlitzer

pygmt/tests/test_grdfill.py

@@ -6,7 +6,7 @@
 import numpy as np
 import pytest
 import xarray as xr
-from pygmt import grdfill, grdinfo
+from pygmt import grdfill, load_dataarray
 from pygmt.datasets import load_earth_relief
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
@@ -18,36 +18,56 @@ def fixture_grid():
     Load the grid data from the sample earth_relief file and set value(s) to
     NaN.
     """
-    grid = load_earth_relief(registration="pixel", region=[-5, 5, -5, 5])
-    grid[3:5, 3:5] = np.nan
-    grid[5:7, 5:7] = np.inf
+    grid = load_earth_relief(registration="pixel", region=[125, 130, -25, -20])
+    grid[2:4, 1:3] = np.nan
+    grid[0:2, 2:4] = np.inf
     return grid
 
 
-def test_grdfill_dataarray_out(grid):
+@pytest.fixture(scope="module", name="expected_grid")
+def fixture_grid_result():
     """
-    grdfill with a DataArray output.
+    Load the expected grdfill grid result.
+    """
+    return xr.DataArray(
+        data=[
+            [442.5, 439.0, np.inf, np.inf, 508.0],
+            [393.0, 364.5, np.inf, np.inf, 506.5],
+            [362.0, 20.0, 20.0, 373.5, 402.5],
+            [321.5, 20.0, 20.0, 356.0, 422.5],
+            [282.5, 318.0, 326.5, 379.5, 383.5],
+        ],
+        coords=dict(
+            lon=[125.5, 126.5, 127.5, 128.5, 129.5],
+            lat=[-24.5, -23.5, -22.5, -21.5, -20.5],
+        ),
+        dims=["lat", "lon"],
+    )
+
+
+def test_grdfill_dataarray_out(grid, expected_grid):
+    """
+    Test grdfill with a DataArray output.
     """
     result = grdfill(grid=grid, mode="c20")
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result[4, 4] == 20
-    assert result[5, 5] == np.inf
-    assert not result.isnull().all()  # check that no NaN values exists
     assert result.gmt.gtype == 1  # Geographic grid
     assert result.gmt.registration == 1  # Pixel registration
+    # check information of the output grid
+    xr.testing.assert_allclose(a=result, b=expected_grid)
 
 
-def test_grdfill_file_out(grid):
+def test_grdfill_file_out(grid, expected_grid):
     """
-    grdfill with an outgrid set.
+    Test grdfill with an outgrid set.
     """
     with GMTTempFile(suffix=".nc") as tmpfile:
         result = grdfill(grid=grid, mode="c20", outgrid=tmpfile.name)
         assert result is None  # return value is None
         assert os.path.exists(path=tmpfile.name)  # check that outgrid exists
-        result = grdinfo(tmpfile.name, per_column=True).strip()
-        assert result == "-5 5 -5 5 -5130.5 inf 1 1 10 10 1 1"
+        temp_grid = load_dataarray(tmpfile.name)
+        xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
 def test_grdfill_required_args(grid):