*: add tests

[cyphar]

Currently all the testing I'm doing is manual, we need to have some actual testing. Namely integration testing (using bats) for the actual umoci tool as well as unit tests for the libraries. Another nice thing would be to have validation testing against the OCI validation tooling.

• Unit tests.
  • Add tests for unpack: insufficient pathname sanitisation #27, to make sure we don't break the safety of paths.
  • Add tests for all of the CAS interfaces against a blank repository.
  • Add tests for generation of tar stream layers.
  • Add tests for unpacking of layers.
• Integration tests.
  • Test for unpack: doesn't preserve mtime #1, where we run gomtree after extracting the same manifest twice at different times.
  • Test where we pull an image using skopeo, unpack it and then repack it. Then unpack it again to compare the changes (with gomtree).
  • Tests where we unpack things that have changed type.
  • Tests with symlinks that have unusual values (please save me from bad symlink handling).
  • Tests for umoci config to make sure that we set things correctly. Use jq for the testing. We also might want to run the runtime validator against it too.
    • empty config set doesn't change it
    • workingdir.
    • cmd and entrypoint result in the right process.args.
    • metadata: architecture os
    • metadata: author created history [not really sure how to test this]
    • env is set to the right $HOME?
    • Something about volume but I get the feeling it isn't great.
    • user:group is actually parsed according to /etc/passwd.
      • $HOME.
      • and AdditionalGids are set.
  • Add tests for umoci gc to make sure it actually cleans things properly.

[cyphar]

I've been working on this inside https://github.com/cyphar/umoci/tree/add-unit-tests.

[cyphar]

Unit tests implemented in e928b06.

[cyphar]

Integration tests implemented in 8fb8c81.

[cyphar]

There are a ~24 tests. Which is okay for a first pass at testing.