Add support for linewidth in legend frame parsing with tests

Author: K-Mirembe-Mercy

tests/test_linewidth.py

@@ -0,0 +1,2 @@
+def test_linewidth_basic():
+    assert True

ultraplot/axes/base.py

@@ -1699,7 +1699,7 @@ def _parse_frame(guide, fancybox=None, shadow=None, **kwargs):
             alpha=("a", "framealpha", "facealpha"),
             facecolor=("fc", "framecolor", "facecolor"),
             edgecolor=("ec",),
-            edgewidth=("ew",),
+            edgewidth=("ew", "linewidth", "lw"),
         )
         _kw_frame_default = {
             "alpha": f"{guide}.framealpha",

ultraplot/legend.py

@@ -1945,19 +1945,31 @@ def _build_legends(
         if multi:
             objs = lax._parse_legend_centered(pairs, kw_frame=kw_frame, **kwargs)
         else:
-            kwargs.update({key: kw_frame.pop(key) for key in ("shadow", "fancybox")})
+            kwargs.update(
+                {
+                    key: kw_frame[key]
+                    for key in ("shadow", "fancybox")
+                    if key in kw_frame
+                }
+            )
             objs = [
                 lax._parse_legend_aligned(
                     pairs, ncol=inputs.ncol, order=inputs.order, **kwargs
                 )
             ]
-            objs[0].legendPatch.update(kw_frame)
-        for obj in objs:
+            frame = objs[0].legendPatch
+frame.update(kw_frame)
+
+if "linewidth" in kw_frame:
+    frame.set_linewidth(kw_frame["linewidth"])
+elif "lw" in kw_frame:
+    frame.set_linewidth(kw_frame["lw"])
+for obj in objs:
             if hasattr(lax, "legend_") and lax.legend_ is None:
                 lax.legend_ = obj
             else:
                 lax.add_artist(obj)
-        return objs
+return objs
 
     def _apply_handle_styles(self, objs, *, kw_text, kw_handle):
         """

ultraplot/tests/test_legend.py

@@ -22,6 +22,13 @@ def test_auto_legend(rng):
     ix = ax.inset_axes((-0.2, 0.8, 0.5, 0.5), zoom=False)
     ix.line(rng.random((5, 2)), labels=list("pq"))
     ax.legend(loc="b", order="F", edgecolor="red9", edgewidth=3)
+    # Test lw
+    leg = ax.legend(frameon=True, lw=5)
+    assert leg.get_frame().get_linewidth() == 5
+
+    # Test lw alias
+    leg2 = ax.legend(frameon=True, lw=3)
+    assert leg2.get_frame().get_linewidth() == 3
     return fig