Make _parse_size robust to already parsed values (#142)

* Make _parse_size robust to already parsed values
(needed for unpickling a folium Map)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Add safety & tests

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

branca/utilities.py

@@ -414,6 +414,13 @@ def _parse_size(value):
             raise ValueError(
                 f"Cannot parse {value!r}, it should be a number followed by a unit.",
             )
+    elif (
+        isinstance(value, tuple)
+        and isinstance(value[0], (int, float))
+        and isinstance(value[1], str)
+    ):
+        # value had been already parsed
+        return (float(value[0]), value[1])
     else:
         raise TypeError(
             f"Cannot parse {value!r}, it should be a number or a string containing a number and a unit.",

tests/test_utilities.py

@@ -116,6 +116,8 @@ def test_color_avoid_unexpected_error():
         ("100%   ", (100.0, "%")),
         ("3 vw", (3.0, "vw")),
         ("3.14 rem", (3.14, "rem")),
+        ((1, "px"), (1.0, "px")),
+        ((80.0, "%"), (80.0, "%")),
     ],
 )
 def test_parse_size(value, result):
@@ -128,6 +130,7 @@ def test_parse_size(value, result):
         "what?",
         "1.21 jigawatts",
         ut._parse_size,
+        (1.21, 4.9),
     ],
 )
 def test_parse_size_exceptions(value):