Add tests to bring our code coverage to ~90%

[Flu]

At the moment our test coverage is somewhere at about 57%, which means there are large portions of the file that the E2E tests don't cover at all.

Goal

Find the instructions we are not testing at all and write tests for them and add them to the test suite.

Run the cabal test and look at the test coverage statistics ("Alternatives" or "Expressions", not "Top Level Definitions"). Cabal now generates those in an html file. If you run it, it will point out the exact location and you can open them with a browser.

By my count, the following instructions are either not tested at all or not enough:

• ADC
• BRCS
• BRGE
• BRHC
• BRHS
• BRID
• BRIE
• BRPL
• BRSH
• BRTC
• BRTS
• BRVC
• BRVS
• CBR
• COM
• CP
• CPC
• CPSE
• MULS