Merge branch 'uk/checkout-ambiguous-ref'

* uk/checkout-ambiguous-ref:
  Rename t2019 with typo "amiguous" that meant "ambiguous"
  checkout: rearrange update_refs_for_switch for clarity
  checkout: introduce --detach synonym for "git checkout foo^{commit}"
  checkout: split off a function to peel away branchname arg
  checkout: fix bug with ambiguous refs

Conflicts:
	builtin/checkout.c

2 files changed, 154 insertions, 0 deletions

diff --git a/t/t2019-checkout-ambiguous-ref.sh b/t/t2019-checkout-ambiguous-ref.sh
new file mode 100755
index 0000000000..943541d40d
--- /dev/null
+++ b/t/t2019-checkout-ambiguous-ref.sh
@@ -0,0 +1,59 @@
+#!/bin/sh
+
+test_description='checkout handling of ambiguous (branch/tag) refs'
+. ./test-lib.sh
+
+test_expect_success 'setup ambiguous refs' '
+	test_commit branch file &&
+	git branch ambiguity &&
+	git branch vagueness &&
+	test_commit tag file &&
+	git tag ambiguity &&
+	git tag vagueness HEAD:file &&
+	test_commit other file
+'
+
+test_expect_success 'checkout ambiguous ref succeeds' '
+	git checkout ambiguity >stdout 2>stderr
+'
+
+test_expect_success 'checkout produces ambiguity warning' '
+	grep "warning.*ambiguous" stderr
+'
+
+test_expect_success 'checkout chooses branch over tag' '
+	echo refs/heads/ambiguity >expect &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
+	echo branch >expect &&
+	test_cmp expect file
+'
+
+test_expect_success 'checkout reports switch to branch' '
+	grep "Switched to branch" stderr &&
+	! grep "^HEAD is now at" stderr
+'
+
+test_expect_success 'checkout vague ref succeeds' '
+	git checkout vagueness >stdout 2>stderr &&
+	test_set_prereq VAGUENESS_SUCCESS
+'
+
+test_expect_success VAGUENESS_SUCCESS 'checkout produces ambiguity warning' '
+	grep "warning.*ambiguous" stderr
+'
+
+test_expect_success VAGUENESS_SUCCESS 'checkout chooses branch over tag' '
+	echo refs/heads/vagueness >expect &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
+	echo branch >expect &&
+	test_cmp expect file
+'
+
+test_expect_success VAGUENESS_SUCCESS 'checkout reports switch to branch' '
+	grep "Switched to branch" stderr &&
+	! grep "^HEAD is now at" stderr
+'
+
+test_done
diff --git a/t/t2020-checkout-detach.sh b/t/t2020-checkout-detach.sh
new file mode 100755
index 0000000000..00421453ba
--- /dev/null
+++ b/t/t2020-checkout-detach.sh
@@ -0,0 +1,95 @@
+#!/bin/sh
+
+test_description='checkout into detached HEAD state'
+. ./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
+}
+
+reset () {
+	git checkout master &&
+	check_not_detached
+}
+
+test_expect_success 'setup' '
+	test_commit one &&
+	test_commit two &&
+	git branch branch &&
+	git tag tag
+'
+
+test_expect_success 'checkout branch does not detach' '
+	reset &&
+	git checkout branch &&
+	check_not_detached
+'
+
+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 master &&
+	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_done