Add LineSearchTestCase #21

Job	Run time
test (1.6, x64, ubuntu-latest)	2m 19s
test (1.6, x64, windows-latest)	9m 41s
test (1.6, x64, macOS-latest)	2m 30s
test (1.6, x86, ubuntu-latest)	2m 45s
test (1.6, x86, windows-latest)	15m 1s
test (1, x64, ubuntu-latest)	59s
test (1, x64, windows-latest)	1m 33s
test (1, x64, macOS-latest)	1m 18s
test (1, x86, ubuntu-latest)	1m 5s
test (1, x86, windows-latest)	2m 13s
test (nightly, x64, ubuntu-latest)	1m 32s
test (nightly, x64, windows-latest)	2m 4s
test (nightly, x64, macOS-latest)	2m 33s
test (nightly, x86, ubuntu-latest)	1m 49s
test (nightly, x86, windows-latest)	2m 28s
	49m 50s

Provide feedback