Copy Phrase targetness bug

[lawhead]

Overview

This PR fixes the triggers.txt file output by the Copy Phrase task to correctly label targets.

The error was in the calculation for the next target in the helper function. This method took a parameter for the copy_phrase and one for the typed_letters and used this information to determine the target. However, prior to a recent refactor, the spelled text was updated before writing triggers. In the current code the triggers are written prior to the decision that updates spelled text. So the code was using the last letter of the spelled text rather than the next un-spelled letter.

Given the potential ambiguity here, I refactored the code to make the target_symbol a parameter. This was already being calculated by the Task for use in the session data.

Ticket

https://www.pivotaltracker.com/story/show/179811273

Contributions

• Refactored helper to write the triggers data
• Renamed the method to indicate that it was public
• Updated tests

Test

• Ran the unit tests
• Ran the Copy Phrase task and analyzed the resulting triggers.txt file (along with the session.json file) to confirm that the correct labels were output.