This makes the tests more hermetic, even though I don't think the
default values (taken from `whoami`) can break any tests (then we
would have already seen them break). Now we just need to make the
operation log's timestamps predictable and then we can start using
operation IDs in snapshot tests.
According to the NO_COLOR FAQ, "user-level configuration files [...] should
override $NO_COLOR." https://no-color.org/
Unfortunately this makes it harder to test the $NO_COLOR behavior since the
test environment isn't attached to a tty. We could allocate a pty or
LD_PRELOAD shim to intercept isatty(), but I feel it would be too much to do.
https://github.com/assert-rs/assert_cmd/issues/138
With this patch, the order is this:
`$JJ_EDITOR` environement variable
`ui.editor` config
`$VISUAL` environement variable
`$EDITOR` environement variable
`pico`
That matches git, except that git falls back to an editor determined
at compile time (usually `vi`) instead of using `pico`.
As I said in 095fb9fef4, removing support for `~/.jjconfig` was an
experiment. I've heard from a few people (including in #233) that they
would prefer to have configs in the home directory. This patch
therefore restores that functionality, except I added a `.toml`
extension to the file to clarify the expected format to users and
editors.
After this patch, we still allow configs in `$XDG_CONFIG_HOME` (and
the other paths used by `dirs::config_dir()`), but we error out there
are config files in both that location and `~/.jjconfig.toml`.
