When you need to test a bash script you can use bats for that. That's how it is done:
#!/usr/bin/env bats
@test "addition using bc" {
result="$(echo 2+2 | bc)"
[ "$result" -eq 4 ]
}
@test "addition using dc" {
result="$(echo 2 2+p | dc)"
[ "$result" -eq 4 ]
}
bats
uses special @test
syntax to define tests. Inside the test's body every line should return 0
exit code or the test will fail.
Read full article here with different tools compared: https://medium.com/wemake-services/testing-bash-applications-85512e7fe2de