Get Test coverage of expressions to 80%

[ChrisCoffey]

From a local run of hpc:

confcrypt-0.1.0.0: Test suite confcrypt-test passed
Generating coverage report for confcrypt's test-suite "confcrypt-test"
 56% expressions used (460/811)
 25% boolean coverage (3/12)
       0% guards (0/8), 8 unevaluated
      66% 'if' conditions (2/3), 1 unevaluated
     100% qualifiers (1/1)
 53% alternatives used (39/73)
 71% local declarations used (27/38)
 30% top-level declarations used (38/126)