Before this commit `jj prev` fails if the current working copy commit is a
merge commit. After this commit it will prompt the user to choose the ancestor
they want to select.
#2126
This commit adds commit graphs to most of the tests for `jj prev` to make it
clearer where `@` points before and after `prev` is run.
In addition, there were a couple of tests where the comments suggested the test
meant to have `@` pointing to a specific commit, but it actually pointed to an
empty child of that commit.
This sort of issue also exists in `test_prev_editing`. The test is supposed to
check that `--edit` is implied if you run `jj prev` on an interior commit, but
it actually caused a new empty commit to be created since `@` was sitting on a
tip commit.
Users who edit non-head commits usually expect `jj next/prev` to
continue to edit the next/previous commit, so let's make that the
default behavior. This should not confuse users who don't edit
non-head commits since they will simply not be in this state. My main
concern is that doing `jj next; jj prev` will now usually take you
back to the previous commit, but not if you started on the parent of a
head commit.
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 is a naive implementation, which cannot deal with multiple children
or parents stemming from merges.
Note: I gave each command separate a separate argument struct
for extensibility.
Fixes#878
