git/t/t2020-checkout-detach.sh
Junio C Hamano b9f2e1a684 checkout: omit "tracking" information on a detached HEAD
By definition, a detached HEAD state is tentative and there is no
configured "upstream" that it always wants to integrate with.  But
if you detach from a branch that is behind its upstream, e.g.,

    $ git checkout -t -b main origin/main
    $ git checkout main
    $ git reset --hard HEAD^
    $ git checkout --detach main

you'd see "you are behind your upstream origin/main".  This does not
happen when you replace the last step in the above with any of these

    $ git checkout HEAD^0
    $ git checkout --detach HEAD
    $ git checkout --detach origin/main

Before 32669671 (checkout: introduce --detach synonym for "git
checkout foo^{commit}", 2011-02-08) introduced the "--detach"
option, the rule to decide if we show the tracking information
used to be:

    If --quiet is not given, and if the given branch name is a real
    local branch (i.e. the one we can compute the file path under
    .git/, like 'refs/heads/master' or "HEAD" which stand for the
    name of the current branch", then give the tracking information.

to exclude things like "git checkout master^0" (which was the
official way to detach HEAD at the commit before that commit) and
"git checkout origin/master^0" from showing tracking information,
but still do show the tracking information for the current branch
for "git checkout HEAD".  The introduction of an explicit option
"--detach" broke this subtley.  The new rule should have been

    If --quiet is given, do not bother with tracking info.
    If --detach is given, do not bother with tracking info.

    Otherwise, if we know that the branch name given is a real local
    branch, or if we were given "HEAD" and "HEAD" is not detached,
    then attempt to show the tracking info.

but it allowed "git checkout --detach master" to also show the
tracking info by mistake.  Let's tighten the rule to fix this.

Reported-by: mirth hickford <mirth.hickford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-03-30 17:53:25 -07:00

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#!/bin/sh
test_description='checkout into detached HEAD state'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
TEST_PASSES_SANITIZE_LEAK=true
. ./test-lib.sh
check_detached () {
test_must_fail git symbolic-ref -q HEAD >/dev/null
}
check_not_detached () {
git symbolic-ref -q HEAD >/dev/null
}
PREV_HEAD_DESC='Previous HEAD position was'
check_orphan_warning() {
test_grep "you are leaving $2 behind" "$1" &&
test_grep ! "$PREV_HEAD_DESC" "$1"
}
check_no_orphan_warning() {
test_grep ! "you are leaving .* commit.*behind" "$1" &&
test_grep "$PREV_HEAD_DESC" "$1"
}
reset () {
git checkout main &&
check_not_detached
}
test_expect_success 'setup' '
test_commit one &&
test_commit two &&
test_commit three && git tag -d three &&
test_commit four && git tag -d four &&
git branch branch &&
git tag tag
'
test_expect_success 'checkout branch does not detach' '
reset &&
git checkout branch &&
check_not_detached
'
for opt in "HEAD" "@"
do
test_expect_success "checkout $opt no-op/don't detach" '
reset &&
cat .git/HEAD >expect &&
git checkout $opt &&
cat .git/HEAD >actual &&
check_not_detached &&
test_cmp expect actual
'
done
test_expect_success 'checkout tag detaches' '
reset &&
git checkout tag &&
check_detached
'
test_expect_success 'checkout branch by full name detaches' '
reset &&
git checkout refs/heads/branch &&
check_detached
'
test_expect_success 'checkout non-ref detaches' '
reset &&
git checkout branch^ &&
check_detached
'
test_expect_success 'checkout ref^0 detaches' '
reset &&
git checkout branch^0 &&
check_detached
'
test_expect_success 'checkout --detach detaches' '
reset &&
git checkout --detach branch &&
check_detached
'
test_expect_success 'checkout --detach without branch name' '
reset &&
git checkout --detach &&
check_detached
'
test_expect_success 'checkout --detach errors out for non-commit' '
reset &&
test_must_fail git checkout --detach one^{tree} &&
check_not_detached
'
test_expect_success 'checkout --detach errors out for extra argument' '
reset &&
git checkout main &&
test_must_fail git checkout --detach tag one.t &&
check_not_detached
'
test_expect_success 'checkout --detached and -b are incompatible' '
reset &&
test_must_fail git checkout --detach -b newbranch tag &&
check_not_detached
'
test_expect_success 'checkout --detach moves HEAD' '
reset &&
git checkout one &&
git checkout --detach two &&
git diff --exit-code HEAD &&
git diff --exit-code two
'
test_expect_success 'checkout warns on orphan commits' '
reset &&
git checkout --detach two &&
echo content >orphan &&
git add orphan &&
git commit -a -m orphan1 &&
echo new content >orphan &&
git commit -a -m orphan2 &&
orphan2=$(git rev-parse HEAD) &&
git checkout main 2>stderr
'
test_expect_success 'checkout warns on orphan commits: output' '
check_orphan_warning stderr "2 commits"
'
test_expect_success 'checkout warns orphaning 1 of 2 commits' '
git checkout "$orphan2" &&
git checkout HEAD^ 2>stderr
'
test_expect_success 'checkout warns orphaning 1 of 2 commits: output' '
check_orphan_warning stderr "1 commit"
'
test_expect_success 'checkout does not warn leaving ref tip' '
reset &&
git checkout --detach two &&
git checkout main 2>stderr
'
test_expect_success 'checkout does not warn leaving ref tip' '
check_no_orphan_warning stderr
'
test_expect_success 'checkout does not warn leaving reachable commit' '
reset &&
git checkout --detach HEAD^ &&
git checkout main 2>stderr
'
test_expect_success 'checkout does not warn leaving reachable commit' '
check_no_orphan_warning stderr
'
cat >expect <<'EOF'
Your branch is behind 'main' by 1 commit, and can be fast-forwarded.
(use "git pull" to update your local branch)
EOF
test_expect_success 'tracking count is accurate after orphan check' '
reset &&
git branch child main^ &&
git config branch.child.remote . &&
git config branch.child.merge refs/heads/main &&
git checkout child^ &&
git checkout child >stdout &&
test_cmp expect stdout &&
git checkout --detach child >stdout &&
test_grep ! "can be fast-forwarded\." stdout
'
test_expect_success 'no advice given for explicit detached head state' '
# baseline
test_config advice.detachedHead true &&
git checkout child && git checkout HEAD^0 >expect.advice 2>&1 &&
test_config advice.detachedHead false &&
git checkout child && git checkout HEAD^0 >expect.no-advice 2>&1 &&
test_unconfig advice.detachedHead &&
# without configuration, the advice.* variables default to true
git checkout child && git checkout HEAD^0 >actual 2>&1 &&
test_cmp expect.advice actual &&
# with explicit --detach
# no configuration
test_unconfig advice.detachedHead &&
git checkout child && git checkout --detach HEAD^0 >actual 2>&1 &&
test_cmp expect.no-advice actual &&
# explicitly decline advice
test_config advice.detachedHead false &&
git checkout child && git checkout --detach HEAD^0 >actual 2>&1 &&
test_cmp expect.no-advice actual
'
# Detached HEAD tests for GIT_PRINT_SHA1_ELLIPSIS (new format)
test_expect_success 'describe_detached_head prints no SHA-1 ellipsis when not asked to' "
commit=$(git rev-parse --short=12 main^) &&
commit2=$(git rev-parse --short=12 main~2) &&
commit3=$(git rev-parse --short=12 main~3) &&
# The first detach operation is more chatty than the following ones.
cat >1st_detach <<-EOF &&
Note: switching to 'HEAD^'.
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:
git switch -c <new-branch-name>
Or undo this operation with:
git switch -
Turn off this advice by setting config variable advice.detachedHead to false
HEAD is now at \$commit three
EOF
# The remaining ones just show info about previous and current HEADs.
cat >2nd_detach <<-EOF &&
Previous HEAD position was \$commit three
HEAD is now at \$commit2 two
EOF
cat >3rd_detach <<-EOF &&
Previous HEAD position was \$commit2 two
HEAD is now at \$commit3 one
EOF
reset &&
check_not_detached &&
# Various ways of *not* asking for ellipses
sane_unset GIT_PRINT_SHA1_ELLIPSIS &&
git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 1st_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS="no" git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 2nd_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS= git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 3rd_detach actual &&
sane_unset GIT_PRINT_SHA1_ELLIPSIS &&
# We only have four commits, but we can re-use them
reset &&
check_not_detached &&
# Make no mention of the env var at all
git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 1st_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS='nope' &&
git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 2nd_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS=nein &&
git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 3rd_detach actual &&
true
"
# Detached HEAD tests for GIT_PRINT_SHA1_ELLIPSIS (old format)
test_expect_success 'describe_detached_head does print SHA-1 ellipsis when asked to' "
commit=$(git rev-parse --short=12 main^) &&
commit2=$(git rev-parse --short=12 main~2) &&
commit3=$(git rev-parse --short=12 main~3) &&
# The first detach operation is more chatty than the following ones.
cat >1st_detach <<-EOF &&
Note: switching to 'HEAD^'.
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:
git switch -c <new-branch-name>
Or undo this operation with:
git switch -
Turn off this advice by setting config variable advice.detachedHead to false
HEAD is now at \$commit... three
EOF
# The remaining ones just show info about previous and current HEADs.
cat >2nd_detach <<-EOF &&
Previous HEAD position was \$commit... three
HEAD is now at \$commit2... two
EOF
cat >3rd_detach <<-EOF &&
Previous HEAD position was \$commit2... two
HEAD is now at \$commit3... one
EOF
reset &&
check_not_detached &&
# Various ways of asking for ellipses...
# The user can just use any kind of quoting (including none).
GIT_PRINT_SHA1_ELLIPSIS=yes git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 1st_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS=Yes git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 2nd_detach actual &&
GIT_PRINT_SHA1_ELLIPSIS=YES git -c 'core.abbrev=12' checkout HEAD^ >actual 2>&1 &&
check_detached &&
test_cmp 3rd_detach actual &&
true
"
test_done