Fix spelling in tests.

[ci skip]
Add tests for `context_id` existence validation.

There's a typo introduced bug to the error message; not crucial, but
it's something worth fixing.
[ci skip]
Fix `context_id` validation error message.

Tests now pass.
Bump version to 1.4.2

[ci skip]
Add failing tests for context change updates.

This is mainly a just a feature request related to #8.
[ci skip]
Add context change updates' support.

Tests now pass. This closes #8.
Bump version to 1.5.0