@GenericMappingTools/pygmt-contributors Any ideas for how to test this? I have downloaded grid files from scientific cruises to ensure I have gaps in the data that need to be filled, but I'm not sure how to write a test that retrieves an unfilled grid from something like pygmt.datasets.

@GenericMappingTools/pygmt-contributors Any ideas for how to test this? I have downloaded grid files from scientific cruises to ensure I have gaps in the data that need to be filled, but I'm not sure how to write a test that retrieves an unfilled grid from something like pygmt.datasets.

You can manual set one or more of the data values in grids from pygmt.datasets to NaN to test the result from grdfill. For example:

import numpy as np
import pytest
import xarray as xr
from pygmt import grdfill
from pygmt.datasets import load_earth_relief


@pytest.fixture(scope="module", name="grid")
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")
    grid[10,10] = np.nan
    return grid

def test_grdfilter_dataarray_in_dataarray_out(grid):
    """
    grdfill an input DataArray, and output as DataArray.
    """
    result = grdfill(grid=grid,mode="c20")
    # check information of the output grid
    assert isinstance(result, xr.DataArray)
    assert result[10,10] == 20

You can manual set one or more of the data values in grids from pygmt.datasets to NaN to test the result from grdfill. For example:

Thanks @meghanrjones!

What is the preferred was for denoting required parameters? I think there should be some indication in the method docs that mode (-A) is required.