Add some more unit tests #60

Job	Run time
busted (luajit-openresty, ubuntu-latest)	31s
busted (luajit-openresty, windows-latest)	1m 32s
busted (luajit-openresty, macos-latest)	1m 26s
busted (luajit-2.1.0-beta3, ubuntu-latest)	29s
busted (luajit-2.1.0-beta3, windows-latest)	1m 58s
busted (luajit-2.1.0-beta3, macos-latest)	1m 15s
busted (luajit-git, ubuntu-latest)	31s
busted (luajit-git, windows-latest)	1m 23s
busted (luajit-git, macos-latest)	52s
busted (5.4.6, ubuntu-latest)	33s
busted (5.4.6, windows-latest)	1m 29s
busted (5.4.6, macos-latest)	42s
busted (5.1.5, ubuntu-latest)	34s
busted (5.1.5, windows-latest)	1m 30s
busted (5.1.5, macos-latest)	47s
busted (5.3.6, ubuntu-latest)	36s
busted (5.3.6, windows-latest)	1m 43s
busted (5.3.6, macos-latest)	44s
finish	4s
	18m 39s

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