test: verify only leaf dir's inexistence

[AirQuick]

Some Bats tests verifies that a directory does not exist, which is error prone.
This pull request enhances it so that the tests also verify that the parent dir does exist.

Also added are some minor improvements.

d42f4e5 is a temporary commit to verify the dir inexistence check.

[commit-lint]

Tests

• verify that only leaf dir not exist (c83d905)
• pushd before calling each case (ecd81d9)
• comment about a quote char in CMD /C option (1c9a256)
• use parent dir absolute path variable (d40aace)
• add comments to setup() and teardown() (ccfa9f0)
• fail in leaf dir check deliberately (d42f4e5)
• remove unnecessary SAXON_CP (66ec608)
• not necessary to do pushd (abfedc8)

Contributors

@AirQuick

[AirQuick]

The temporary commit failed as expected:

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• GitHub Actions: Linux, macOS, Windows
• Travis CI
• Azure Pipelines: macOS, Windows