refactor(test): Rely on trait, rather than direct calls

[epage]

This is a step towards #72

v0.4.7

json/basic/canada       time:   [10.272 ms 10.308 ms 10.347 ms]
json/verbose/canada     time:   [32.539 ms 32.714 ms 32.893 ms]
json/dispatch/canada    time:   [8.9747 ms 8.9926 ms 9.0118 ms]
json/streaming/canada   time:   [10.612 ms 10.667 ms 10.726 ms]

#276

json/basic/canada       time:   [10.226 ms 10.241 ms 10.256 ms]
json/unit/canada        time:   [8.6800 ms 8.7021 ms 8.7269 ms]
json/verbose/canada     time:   [30.948 ms 30.991 ms 31.037 ms]
json/dispatch/canada    time:   [8.5036 ms 8.5273 ms 8.5542 ms]
json/streaming/canada   time:   [10.727 ms 10.753 ms 10.781 ms]

#277

json/basic/canada       time:   [9.6649 ms 9.6840 ms 9.7037 ms]
json/unit/canada        time:   [9.0364 ms 9.0944 ms 9.1513 ms]
json/verbose/canada     time:   [31.032 ms 31.072 ms 31.114 ms]
json/dispatch/canada    time:   [8.5341 ms 8.5538 ms 8.5749 ms]
json/streaming/canada   time:   [10.679 ms 10.707 ms 10.739 ms]

[coveralls]

Pull Request Test Coverage Report for Build 5476587785

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 50.589%

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Totals
Change from base Build 5476576828:	0.2%
Covered Lines:	1245
Relevant Lines:	2461

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💛 - Coveralls