fix prop parsing

Author: cvanelteren

ultraplot/tests/test_thread_safety.py

@@ -6,7 +6,7 @@ def modify_rc_on_thread(prop: str, value=None, with_context=True):
     Apply arbitrary rc parameters in a thread-safe manner.
     """
     if with_context:
-        with uplt.rc.context(fontsize=value):
+        with uplt.rc.context(**{prop: value}):
             assert uplt.rc[prop] == value, f"Thread {id} failed to set rc params"
     else:
         assert uplt.rc[prop] == value, f"Thread {id} failed to set rc params"
@@ -36,9 +36,9 @@ def wrapped_func(**kw):
             w.join()
 
     if exceptions:
-        raise RuntimeError(f"Thread raised exception: {exceptions[0]}") from exceptions[
-            0
-        ]
+        raise RuntimeError(
+            f"Thread raised exception: {exceptions[0]} with {kwargs=}"
+        ) from exceptions[0]
 
     if record:
         raise RuntimeError("Thread raised a warning")
@@ -52,7 +52,7 @@ def wrapped_func(**kw):
         ("abc", "A. a. aa aaa aaaa.".split()),
     ],
 )
-def test_setting_without_context(prop, options, with_context):
+def test_setting_rc(prop, options, with_context):
     """
     Test the thread safety of a context setting
     """