this greatly speeds up the time to run all tests, at the cost of slightly larger recompile times for individual tests.
this unfortunately adds the requirement that all tests are listed in `runner.rs` for the crate.
to avoid forgetting, i've added a new test that ensures the directory is in sync with the file.
## benchmarks
before this change, recompiling all tests took 32-50 seconds and running a single test took 3.5 seconds:
```
; hyperfine 'touch lib/src/lib.rs && cargo t --test test_working_copy'
Time (mean ± σ): 3.543 s ± 0.168 s [User: 2.597 s, System: 1.262 s]
Range (min … max): 3.400 s … 3.847 s 10 runs
```
after this change, recompiling all tests take 4 seconds:
```
; hyperfine 'touch lib/src/lib.rs ; cargo t --test runner --no-run'
Time (mean ± σ): 4.055 s ± 0.123 s [User: 3.591 s, System: 1.593 s]
Range (min … max): 3.804 s … 4.159 s 10 runs
```
and running a single test takes about the same:
```
; hyperfine 'touch lib/src/lib.rs && cargo t --test runner -- test_working_copy'
Time (mean ± σ): 4.129 s ± 0.120 s [User: 3.636 s, System: 1.593 s]
Range (min … max): 3.933 s … 4.346 s 10 runs
```
about 1.4 seconds of that is the time for the runner, of which .4 is the time for the linker. so
there may be room for further improving the times.
This reimplements the change 9faa4670d5 "cli: on init, import git refs prior
to importing HEAD." Initialization is special because the HEAD ref isn't
available to jj yet, and there is an empty working-copy commit.
The initialization function could be refactored to go through the common code
path, but I think doing that would make future improvement harder. We might
want to initialize tracking branches based on .git/config for example.
Fixes#2942
This initializes a git backed repo.
* It does the same thing as `jj init --git` except that it
has a --colocated flag to explicitly specify that we want
the .git repo to be side-by-side the .jj repo in the working
directory.
* `jj init --git` will keep the current behaviour and will not
be able to create colocated git backed repos.
* Update test snapshots.
