Change test_grdfilter.py to use static_earth_relief (#1678)

pygmt/tests/test_grdfilter.py

@@ -4,92 +4,72 @@
 import os
 
 import numpy as np
-import numpy.testing as npt
 import pytest
 import xarray as xr
-from pygmt import grdfilter, grdinfo
-from pygmt.datasets import load_earth_relief
+from pygmt import grdfilter, load_dataarray
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
+from pygmt.helpers.testing import load_static_earth_relief
 
 
 @pytest.fixture(scope="module", name="grid")
 def fixture_grid():
     """
-    Load the grid data from the sample earth_relief file.
+    Load the grid data from the static earth relief file.
     """
-    return load_earth_relief(registration="pixel")
+    return load_static_earth_relief()
 
 
-def test_grdfilter_dataarray_in_dataarray_out(grid):
+@pytest.fixture(scope="module", name="expected_grid")
+def fixture_grid_result():
     """
-    grdfilter an input DataArray, and output as DataArray.
+    Load the expected grdfilter grid result.
     """
-    result = grdfilter(grid=grid, filter="g600", distance="4")
-    # check information of the output grid
-    assert isinstance(result, xr.DataArray)
-    assert result.coords["lat"].data.min() == -89.5
-    assert result.coords["lat"].data.max() == 89.5
-    assert result.coords["lon"].data.min() == -179.5
-    assert result.coords["lon"].data.max() == 179.5
-    npt.assert_almost_equal(result.data.min(), -6147.4907, decimal=2)
-    npt.assert_almost_equal(result.data.max(), 5164.06, decimal=2)
-    assert result.sizes["lat"] == 180
-    assert result.sizes["lon"] == 360
-
-
-def test_grdfilter_dataarray_in_file_out(grid):
-    """
-    grdfilter an input DataArray, and output to a grid file.
-    """
-    with GMTTempFile(suffix=".nc") as tmpfile:
-        result = grdfilter(grid, outgrid=tmpfile.name, filter="g600", distance="4")
-        assert result is None  # grdfilter returns None if output to a file
-        result = grdinfo(tmpfile.name, per_column=True)
-        assert (
-            result == "-180 180 -90 90 -6147.49072266 5164.06005859 1 1 360 180 1 1\n"
-        )
+    return xr.DataArray(
+        data=[
+            [502.61914, 488.27576, 494.10657, 559.06244],
+            [614.6496, 601.4992, 569.9743, 606.0966],
+            [661.41003, 656.9681, 625.1668, 664.40204],
+        ],
+        coords=dict(
+            lon=[-52.5, -51.5, -50.5, -49.5],
+            lat=[-19.5, -18.5, -17.5],
+        ),
+        dims=["lat", "lon"],
+    )
 
 
-def test_grdfilter_file_in_dataarray_out():
+def test_grdfilter_dataarray_in_dataarray_out(grid, expected_grid):
     """
-    grdfilter an input grid file, and output as DataArray.
+    Test grdfilter with an input DataArray, and output as DataArray.
     """
-    outgrid = grdfilter(
-        "@earth_relief_01d", region="0/180/0/90", filter="g600", distance="4"
+    result = grdfilter(
+        grid=grid, filter="g600", distance="4", region=[-53, -49, -20, -17]
     )
-    assert isinstance(outgrid, xr.DataArray)
-    assert outgrid.gmt.registration == 1  # Pixel registration
-    assert outgrid.gmt.gtype == 1  # Geographic type
-    # check information of the output DataArray
-    # the '@earth_relief_01d' is in pixel registration, so the grid range is
-    # not exactly 0/180/0/90
-    assert outgrid.coords["lat"].data.min() == 0.5
-    assert outgrid.coords["lat"].data.max() == 89.5
-    assert outgrid.coords["lon"].data.min() == 0.5
-    assert outgrid.coords["lon"].data.max() == 179.5
-    npt.assert_almost_equal(outgrid.data.min(), -6147.4907, decimal=2)
-    npt.assert_almost_equal(outgrid.data.max(), 5164.06, decimal=2)
-    assert outgrid.sizes["lat"] == 90
-    assert outgrid.sizes["lon"] == 180
+    # check information of the output grid
+    assert isinstance(result, xr.DataArray)
+    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_grdfilter_file_in_file_out():
+def test_grdfilter_dataarray_in_file_out(grid, expected_grid):
     """
-    grdfilter an input grid file, and output to a grid file.
+    Test grdfilter with an input DataArray, and output to a grid file.
     """
     with GMTTempFile(suffix=".nc") as tmpfile:
         result = grdfilter(
-            "@earth_relief_01d",
+            grid,
             outgrid=tmpfile.name,
-            region=[0, 180, 0, 90],
             filter="g600",
             distance="4",
+            region=[-53, -49, -20, -17],
         )
         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)
-        assert result == "0 180 0 90 -6147.49072266 5164.06005859 1 1 180 90 1 1\n"
+        temp_grid = load_dataarray(tmpfile.name)
+        xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
 def test_grdfilter_fails():