feat: testing for Models

[coveralls]

Pull Request Test Coverage Report for Build 27

• 3 of 4 (75.0%) changed or added relevant lines in 3 files are covered.
• 18 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+40.7%) to 73.846%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/gnarly-core/src/utils.ts	0	1	0.0%
<!--	Total:	3	4	75.0%	-->

Files with Coverage Reduction	New Missed Lines	%
packages/gnarly-core/src/models/ExternalTransaction.ts	1	94.12%
packages/gnarly-core/src/globalstate.ts	5	68.18%
packages/gnarly-core/src/utils.ts	12	56.6%
<!--	Total:	18		-->

Totals
Change from base Build 25:	40.7%
Covered Lines:	181
Relevant Lines:	226

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💛 - Coveralls