Add test_interface and updated test_main

[coveralls]

Pull Request Test Coverage Report for Build 32

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.9%) to 86.408%

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Totals
Change from base Build 30:	2.9%
Covered Lines:	89
Relevant Lines:	103

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💛 - Coveralls