chore: add more unit tests

[LinuxSuRen]

No description provided.

[codacy-production]

Coverage summary from Codacy

Merging #15 (0086f37) into master (3e4e392) - See PR on Codacy

Coverage variation	Diff coverage
+29.03%	90.91%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (3e4e392)	259	125	48.26%
Head commit (0086f37)	251 (-8)	194 (+69)	77.29% (+29.03%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#15)	33	30	90.91%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

See your quality gate settings    Change summary preferences