Add a test to make sure the incols parameter works for pandas.DataFrame (#1771)

Author: seisman

pygmt/tests/baseline/test_plot_dataframe_incols.png.dvc

@@ -0,0 +1,4 @@
+outs:
+- md5: bad6889287951b3c888032af6b1fa945
+  size: 7674
+  path: test_plot_dataframe_incols.png

pygmt/tests/test_plot.py

@@ -540,3 +540,18 @@ def test_plot_ogrgmt_file_multipoint_non_default_style():
             style="c0.2c",
         )
         return fig
+
+
+@pytest.mark.mpl_image_compare
+def test_plot_dataframe_incols():
+    """
+    Make sure that the incols parameter works for pandas.DataFrame.
+
+    See https://github.com/GenericMappingTools/pygmt/issues/1440.
+    """
+    data = pd.DataFrame(data={"col1": [-0.5, 0, 0.5], "col2": [-0.75, 0, 0.75]})
+    fig = Figure()
+    fig.plot(
+        data=data, frame=True, region=[-1, 1, -1, 1], projection="X5c", incols=[1, 0]
+    )
+    return fig