git/t/t3202-show-branch.sh
Jeff King 5edd126720 read_ref_at(): special-case ref@{0} for an empty reflog
The previous commit special-cased get_oid_basic()'s handling of ref@{n}
for a reflog with n entries. But its special case doesn't work for
ref@{0} in an empty reflog, because read_ref_at() dies when it notices
the empty reflog!

We can make this work by special-casing this in read_ref_at(). It's
somewhat gross, for two reasons:

  1. We have no reflog entry to describe in the "msg" out-parameter. So
     we have to leave it uninitialized or make something up.

  2. Likewise, we have no oid to put in the "oid" out-parameter. Leaving
     it untouched is actually the best thing here, as all of the callers
     will have initialized it with the current ref value via
     repo_dwim_log(). This is rather subtle, but it is how things worked
     in 6436a20284 (refs: allow @{n} to work with n-sized reflog,
     2021-01-07) before we reverted it.

The key difference from 6436a20284 here is that we'll return "1" to
indicate that we _didn't_ find the requested reflog entry. Coupled with
the special-casing in get_oid_basic() in the previous commit, that's
enough to make looking up ref@{0} work, and we can flip 6436a20284's
test back to expect_success.

It also means that the call in show-branch which segfaulted with
6436a20284 (and which is now tested in t3202) remains OK. The caller
notices that we could not find any reflog entry, and so it breaks out of
its loop, showing nothing. This is different from the current behavior
of producing an error, but it's just as reasonable (and is exactly what
we'd do if you asked it to walk starting at ref@{1} but there was only 1
entry).

Thus nobody should actually look at the reflog entry info we return. But
we'll still put in some fake values just to be on the safe side, since
this is such a subtle and confusing interface. Likewise, we'll document
what's going on in a comment above the function declaration. If this
were a function with a lot of callers, the footgun would probably not be
worth it. But it has only ever had two callers in its 18-year existence,
and it seems unlikely to grow more. So let's hold our noses and let
users enjoy the convenience of a simulated ref@{0}.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-26 10:05:35 -08:00

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#!/bin/sh
test_description='test show-branch'
. ./test-lib.sh
test_expect_success 'error descriptions on empty repository' '
current=$(git branch --show-current) &&
cat >expect <<-EOF &&
error: no commit on branch '\''$current'\'' yet
EOF
test_must_fail git branch --edit-description 2>actual &&
test_cmp expect actual &&
test_must_fail git branch --edit-description $current 2>actual &&
test_cmp expect actual
'
test_expect_success 'fatal descriptions on empty repository' '
current=$(git branch --show-current) &&
cat >expect <<-EOF &&
fatal: no commit on branch '\''$current'\'' yet
EOF
test_must_fail git branch --set-upstream-to=non-existent 2>actual &&
test_cmp expect actual &&
test_must_fail git branch -c new-branch 2>actual &&
test_cmp expect actual
'
test_expect_success 'setup' '
test_commit initial &&
for i in $(test_seq 1 10)
do
git checkout -b branch$i initial &&
test_commit --no-tag branch$i || return 1
done &&
git for-each-ref \
--sort=version:refname \
--format="%(refname:strip=2)" \
"refs/heads/branch*" >branches.sorted &&
sed "s/^> //" >expect <<-\EOF
> ! [branch1] branch1
> ! [branch2] branch2
> ! [branch3] branch3
> ! [branch4] branch4
> ! [branch5] branch5
> ! [branch6] branch6
> ! [branch7] branch7
> ! [branch8] branch8
> ! [branch9] branch9
> * [branch10] branch10
> ----------
> * [branch10] branch10
> + [branch9] branch9
> + [branch8] branch8
> + [branch7] branch7
> + [branch6] branch6
> + [branch5] branch5
> + [branch4] branch4
> + [branch3] branch3
> + [branch2] branch2
> + [branch1] branch1
> +++++++++* [branch10^] initial
EOF
'
test_expect_success 'show-branch with more than 8 branches' '
git show-branch $(cat branches.sorted) >actual &&
test_cmp expect actual
'
test_expect_success 'show-branch with showbranch.default' '
for branch in $(cat branches.sorted)
do
test_config showbranch.default $branch --add || return 1
done &&
git show-branch >actual &&
test_cmp expect actual
'
test_expect_success 'show-branch --color output' '
sed "s/^> //" >expect <<-\EOF &&
> <RED>!<RESET> [branch1] branch1
> <GREEN>!<RESET> [branch2] branch2
> <YELLOW>!<RESET> [branch3] branch3
> <BLUE>!<RESET> [branch4] branch4
> <MAGENTA>!<RESET> [branch5] branch5
> <CYAN>!<RESET> [branch6] branch6
> <BOLD;RED>!<RESET> [branch7] branch7
> <BOLD;GREEN>!<RESET> [branch8] branch8
> <BOLD;YELLOW>!<RESET> [branch9] branch9
> <BOLD;BLUE>*<RESET> [branch10] branch10
> ----------
> <BOLD;BLUE>*<RESET> [branch10] branch10
> <BOLD;YELLOW>+<RESET> [branch9] branch9
> <BOLD;GREEN>+<RESET> [branch8] branch8
> <BOLD;RED>+<RESET> [branch7] branch7
> <CYAN>+<RESET> [branch6] branch6
> <MAGENTA>+<RESET> [branch5] branch5
> <BLUE>+<RESET> [branch4] branch4
> <YELLOW>+<RESET> [branch3] branch3
> <GREEN>+<RESET> [branch2] branch2
> <RED>+<RESET> [branch1] branch1
> <RED>+<RESET><GREEN>+<RESET><YELLOW>+<RESET><BLUE>+<RESET><MAGENTA>+<RESET><CYAN>+<RESET><BOLD;RED>+<RESET><BOLD;GREEN>+<RESET><BOLD;YELLOW>+<RESET><BOLD;BLUE>*<RESET> [branch10^] initial
EOF
git show-branch --color=always $(cat branches.sorted) >actual.raw &&
test_decode_color <actual.raw >actual &&
test_cmp expect actual
'
test_expect_success 'show branch --remotes' '
cat >expect.err <<-\EOF &&
No revs to be shown.
EOF
git show-branch -r 2>actual.err >actual.out &&
test_cmp expect.err actual.err &&
test_must_be_empty actual.out
'
test_expect_success 'show-branch --sparse' '
test_when_finished "git checkout branch10 && git branch -D branchA" &&
git checkout -b branchA branch10 &&
git merge -s ours -m "merge 1 and 10 to make A" branch1 &&
git commit --allow-empty -m "another" &&
git show-branch --sparse >out &&
grep "merge 1 and 10 to make A" out &&
git show-branch >out &&
! grep "merge 1 and 10 to make A" out &&
git show-branch --no-sparse >out &&
! grep "merge 1 and 10 to make A" out
'
test_expect_success 'setup show branch --list' '
sed "s/^> //" >expect <<-\EOF
> [branch1] branch1
> [branch2] branch2
> [branch3] branch3
> [branch4] branch4
> [branch5] branch5
> [branch6] branch6
> [branch7] branch7
> [branch8] branch8
> [branch9] branch9
> * [branch10] branch10
EOF
'
test_expect_success 'show branch --list' '
git show-branch --list $(cat branches.sorted) >actual &&
test_cmp expect actual
'
test_expect_success 'show branch --list has no --color output' '
git show-branch --color=always --list $(cat branches.sorted) >actual &&
test_cmp expect actual
'
test_expect_success 'show branch --merge-base with one argument' '
for branch in $(cat branches.sorted)
do
git rev-parse $branch >expect &&
git show-branch --merge-base $branch >actual &&
test_cmp expect actual || return 1
done
'
test_expect_success 'show branch --merge-base with two arguments' '
for branch in $(cat branches.sorted)
do
git rev-parse initial >expect &&
git show-branch --merge-base initial $branch >actual &&
test_cmp expect actual || return 1
done
'
test_expect_success 'show branch --merge-base with N arguments' '
git rev-parse initial >expect &&
git show-branch --merge-base $(cat branches.sorted) >actual &&
test_cmp expect actual &&
git merge-base $(cat branches.sorted) >actual &&
test_cmp expect actual
'
# incompatible options
while read combo
do
test_expect_success "show-branch $combo (should fail)" '
test_must_fail git show-branch $combo 2>error &&
grep -e "cannot be used together" -e "usage:" error
'
done <<\EOF
--all --reflog
--merge-base --reflog
--list --merge-base
--reflog --current
EOF
# unnegatable options
for opt in topo-order date-order reflog
do
test_expect_success "show-branch --no-$opt (should fail)" '
test_must_fail git show-branch --no-$opt 2>err &&
grep "unknown option .no-$opt." err
'
done
test_expect_success 'error descriptions on non-existent branch' '
cat >expect <<-EOF &&
error: no branch named '\''non-existent'\''
EOF
test_must_fail git branch --edit-description non-existent 2>actual &&
test_cmp expect actual
'
test_expect_success 'fatal descriptions on non-existent branch' '
cat >expect <<-EOF &&
fatal: branch '\''non-existent'\'' does not exist
EOF
test_must_fail git branch --set-upstream-to=non-existent non-existent 2>actual &&
test_cmp expect actual &&
cat >expect <<-EOF &&
fatal: no branch named '\''non-existent'\''
EOF
test_must_fail git branch -c non-existent new-branch 2>actual &&
test_cmp expect actual &&
test_must_fail git branch -m non-existent new-branch 2>actual &&
test_cmp expect actual
'
test_expect_success 'error descriptions on orphan branch' '
test_when_finished git worktree remove -f wt &&
git worktree add wt --detach &&
git -C wt checkout --orphan orphan-branch &&
test_branch_op_in_wt() {
test_orphan_error() {
test_must_fail git $* 2>actual &&
test_grep "no commit on branch .orphan-branch. yet$" actual
} &&
test_orphan_error -C wt branch $1 $2 && # implicit branch
test_orphan_error -C wt branch $1 orphan-branch $2 && # explicit branch
test_orphan_error branch $1 orphan-branch $2 # different worktree
} &&
test_branch_op_in_wt --edit-description &&
test_branch_op_in_wt --set-upstream-to=ne &&
test_branch_op_in_wt -c new-branch
'
test_expect_success 'setup reflogs' '
test_commit base &&
git checkout -b branch &&
test_commit one &&
git reset --hard HEAD^ &&
test_commit two &&
test_commit three
'
test_expect_success '--reflog shows reflog entries' '
cat >expect <<-\EOF &&
! [branch@{0}] (0 seconds ago) commit: three
! [branch@{1}] (60 seconds ago) commit: two
! [branch@{2}] (2 minutes ago) reset: moving to HEAD^
! [branch@{3}] (2 minutes ago) commit: one
----
+ [branch@{0}] three
++ [branch@{1}] two
+ [branch@{3}] one
++++ [branch@{2}] base
EOF
# the output always contains relative timestamps; use
# a known time to get deterministic results
GIT_TEST_DATE_NOW=$test_tick \
git show-branch --reflog branch >actual &&
test_cmp expect actual
'
test_expect_success '--reflog handles missing reflog' '
git reflog expire --expire=now branch &&
git show-branch --reflog branch >actual &&
test_must_be_empty actual
'
test_done