Testing requires Seaborn and put in a better AttributeError exception…

… if setting impossible rcParams

Stoner/plot/formats.py

@@ -292,6 +292,8 @@ def __setattr__(self, name, value):
         """Ensure stylesheet can't be overwritten and provide magic for template attributes."""
         if name.startswith("template_"):
             attrname = _add_dots(name[9:])
+            if attrname not in plt.rcParams.keys():
+                raise AttributeError(f"{attrname} is not an attribute of matplotlib.rcParams!")
             plt.rcParams[attrname] = value
             super().__setattr__(name, value)
         else:

requirements.txt

@@ -17,3 +17,4 @@ multiprocess>=0.70
 dill>=0.2.8
 urllib3>=1.26
 dateutil>=2.8
+seaborn>=0.13

tests/test-env.yml

@@ -33,3 +33,4 @@ dependencies:
   - python-dateutil >=2.8
   - hyperspy
   - fabio
+  - seaborn >=0.13