The `AnyError` placeholder error can cause tests to succeed for errors
other than what was expected. That is, the use of `AnyError` can mask
bugs in a unit test. So replace it with the specific error, or error type,
the test expects to be raised.
This does not remove the anyError structure because it is used in
the TestCase.DoesNotCompile() method. To keep the size of this change
as small as possible I want to defer updating that use to a separate
change. However, remove the public AnyError var so future test writers
don't attempt to use it.
- Move NewEnvListVar to pkg/eval/vars.
- De-export GlobPattern, GlobFlag and ExternalCmd.
- Merge editor.go and chdir.go into eval.go, value_helper.go into compile_value.go.
- Remove eval_internal_test.go and replace it with a new test for $pid.
Improve coverage of pkg/eval/external_cmd.go from 58.3% to 86.1% as
measured by `make test` on macOS.
This would have been a smaller change but I felt it was important to
actually validate the exception raised when an external command fails
rather than simply using `.ThrowsAny()`. That necessitated augmenting
the pkg/eval/testutils.go module.
Related #1062
