Starting with version 1.7.0 Bats shows warnings about issues it found during the test run. They are printed on stderr after all other output:
BW01.bats ✓ Trigger BW01 1 test, 0 failures The following warnings were encountered during tests: BW01: `run`'s command `=0 actually-intended-command with some args` exited with code 127, indicating 'Command not found'. Use run's return code checks, e.g. `run -127`, to fix this message. (from function `run' in file lib/bats-core/test_functions.bash, line 299, in test file test/fixtures/warnings/BW01.bats, line 3)
A warning will not make a successful run fail but should be investigated and taken seriously, since it hints at a possible error.
Currently, Bats emits the following warnings:
- BW01: run’s command <command> exited with code 127, indicating ‘Command not found’. Use run’s return code checks, e.g. run -127, to fix this message.
- BW02: <feature> requires at least BATS_VERSION=<version>. Use bats_require_minimum_version <version> to fix this message.