While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
See issue #2203. An undotted i uncrossed t. When using namespaces, need to call attributes() to access the attributes before trying to access them directly. Failure to do so in castToFormula caused problem for shared formulas.
Surprisingly, this didn't show up in unit tests. Perhaps sharing the same formula between two cells isn't common. It did show up in Chart Samples. I've added a test.
I was really inclined to merge this right away. Not to worry - I can control myself. It should be moved fairly quickly nevertheless.