test

add test case for string argument #294

Job	Run time
ruby-versions / Generate Ruby versions	4s
build (2.7 / ubuntu-latest)	26s
build (2.6 / windows-latest)	1m 38s
build (2.7 / macos-latest)	36s
build (3.1 / ubuntu-latest)	11s
build (2.7 / windows-latest)	1m 45s
build (2.6 / ubuntu-latest)	27s
build (3.1 / windows-latest)	1m 1s
build (3.2 / windows-latest)	1m 4s
build (3.1 / macos-latest)	15s
build (3.2 / ubuntu-latest)	14s
build (3.2 / macos-latest)	16s
build (3.4 / ubuntu-latest)	12s
build (3.0 / macos-latest)	15s
build (3.4 / macos-latest)	15s
build (3.3 / macos-latest)	14s
build (3.0 / windows-latest)	1m 17s
build (3.3 / windows-latest)	50s
build (3.0 / ubuntu-latest)	13s
build (head / windows-latest)	1m 19s
build (3.4 / windows-latest)	1m 19s
build (head / ubuntu-latest)	12s
build (3.3 / ubuntu-latest)	11s
build (2.6 / macos-latest)	30s
build (truffleruby-head / ubuntu-latest)	32s
build (truffleruby / macos-latest)	21s
build (head / macos-latest)	14s
build (truffleruby-head / macos-latest)	24s
build (truffleruby / ubuntu-latest)	25s
	16m 40s

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