Migrate Figure.legend tests to use dvc (#1166)

Author: willschlitzer

pygmt/tests/baseline/test_legend_default_position.png

@@ -0,0 +1,4 @@
+outs:
+- md5: 7cc85638c576d10348126373fc2a5762
+  size: 25898
+  path: test_legend_default_position.png

pygmt/tests/baseline/test_legend_default_position.png.dvc

@@ -0,0 +1,4 @@
+outs:
+- md5: d794a59f0fbdb7c8e8a4a1ea5c741470
+  size: 24298
+  path: test_legend_position.png

pygmt/tests/baseline/test_legend_position.png

@@ -0,0 +1,4 @@
+outs:
+- md5: 5d0420febe0e0a5ae9ffc0a67879fc61
+  size: 61634
+  path: test_legend_specfile.png

pygmt/tests/baseline/test_legend_position.png.dvc

@@ -10,27 +10,22 @@
 @pytest.mark.mpl_image_compare
 def test_legend_position():
     """
-    Try positioning with each of the four legend coordinate systems.
+    Test that plots a position with each of the four legend coordinate systems.
     """
 
     fig = Figure()
-
     fig.basemap(region=[-2, 2, -2, 2], frame=True)
-
     positions = ["jTR+jTR", "g0/1", "n0.2/0.2", "x4i/2i/2i"]
-
     for i, position in enumerate(positions):
-
         fig.plot(x=[0], y=[0], style="p10p", label=i)
         fig.legend(position=position, box=True)
-
     return fig
 
 
 @pytest.mark.mpl_image_compare
 def test_legend_default_position():
     """
-    Try using the default legend position.
+    Test using the default legend position.
     """
 
     fig = Figure()
@@ -98,15 +93,11 @@ def test_legend_specfile():
 """
 
     with GMTTempFile() as specfile:
-
         with open(specfile.name, "w") as file:
             file.write(specfile_contents)
-
         fig = Figure()
-
         fig.basemap(projection="x6i", region=[0, 1, 0, 1], frame=True)
         fig.legend(specfile.name, position="JTM+jCM+w5i")
-
     return fig