detached-stash: tests of git stash with stash-like arguments

Adds new tests which check that:
* git stash branch handles a stash-like argument when there is a stash stack
* git stash branch handles a stash-like argument when there is not a stash stack
* git stash show handles a stash-like argument when there is a stash stack
* git stash show handles a stash-like argument when there is not a stash stack
* git stash drop fails early if the specified argument is not a stash reference
* git stash pop fails early if the specified argument is not a stash reference
* git stash * fails early if the reference supplied is bogus
* git stash fails early with stash@{n} where n >= length of stash log

Helped-by: Johannes Sixt
Signed-off-by: Jon Seymour <jon.seymour@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3903-stash.sh

@@ -378,4 +378,116 @@ test_expect_failure 'stash file to directory' '
 	test foo = "$(cat file/file)"
 '
 
+test_expect_success 'stash branch - no stashes on stack, stash-like argument' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD" &&
+	git reset --hard &&
+	echo foo >> file &&
+	STASH_ID=$(git stash create) &&
+	git reset --hard &&
+	git stash branch stash-branch ${STASH_ID} &&
+	test_when_finished "git reset --hard HEAD && git checkout master && git branch -D stash-branch" &&
+	test $(git ls-files --modified | wc -l) -eq 1
+'
+
+test_expect_success 'stash branch - stashes on stack, stash-like argument' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD" &&
+	git reset --hard &&
+	echo foo >> file &&
+	git stash &&
+	test_when_finished "git stash drop" &&
+	echo bar >> file &&
+	STASH_ID=$(git stash create) &&
+	git reset --hard &&
+	git stash branch stash-branch ${STASH_ID} &&
+	test_when_finished "git reset --hard HEAD && git checkout master && git branch -D stash-branch" &&
+	test $(git ls-files --modified | wc -l) -eq 1
+'
+
+test_expect_success 'stash show - stashes on stack, stash-like argument' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD" &&
+	git reset --hard &&
+	echo foo >> file &&
+	git stash &&
+	test_when_finished "git stash drop" &&
+	echo bar >> file &&
+	STASH_ID=$(git stash create) &&
+	git reset --hard &&
+	git stash show ${STASH_ID}
+'
+test_expect_success 'stash show - no stashes on stack, stash-like argument' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD" &&
+	git reset --hard &&
+	echo foo >> file &&
+	STASH_ID=$(git stash create) &&
+	git reset --hard &&
+	git stash show ${STASH_ID}
+'
+
+test_expect_success 'stash drop - fail early if specified stash is not a stash reference' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD && git stash clear" &&
+	git reset --hard &&
+	echo foo > file &&
+	git stash &&
+	echo bar > file &&
+	git stash &&
+	test_must_fail "git stash drop $(git rev-parse stash@{0})" &&
+	git stash pop &&
+	test bar = "$(cat file)" &&
+	git reset --hard HEAD
+'
+
+test_expect_success 'stash pop - fail early if specified stash is not a stash reference' '
+	git stash clear &&
+	test_when_finished "git reset --hard HEAD && git stash clear" &&
+	git reset --hard &&
+	echo foo > file &&
+	git stash &&
+	echo bar > file &&
+	git stash &&
+	test_must_fail "git stash pop $(git rev-parse stash@{0})" &&
+	git stash pop &&
+	test bar = "$(cat file)" &&
+	git reset --hard HEAD
+'
+
+test_expect_success 'ref with non-existant reflog' '
+	git stash clear &&
+	echo bar5 > file &&
+	echo bar6 > file2 &&
+	git add file2 &&
+	git stash &&
+	! "git rev-parse --quiet --verify does-not-exist" &&
+	test_must_fail "git stash drop does-not-exist" &&
+	test_must_fail "git stash drop does-not-exist@{0}" &&
+	test_must_fail "git stash pop does-not-exist" &&
+	test_must_fail "git stash pop does-not-exist@{0}" &&
+	test_must_fail "git stash apply does-not-exist" &&
+	test_must_fail "git stash apply does-not-exist@{0}" &&
+	test_must_fail "git stash show does-not-exist" &&
+	test_must_fail "git stash show does-not-exist@{0}" &&
+	test_must_fail "git stash branch tmp does-not-exist" &&
+	test_must_fail "git stash branch tmp does-not-exist@{0}" &&
+	git stash drop
+'
+
+test_expect_success 'invalid ref of the form stash@{n}, n >= N' '
+	git stash clear &&
+	test_must_fail "git stash drop stash@{0}" &&
+	echo bar5 > file &&
+	echo bar6 > file2 &&
+	git add file2 &&
+	git stash &&
+	test_must_fail "git drop stash@{1}" &&
+	test_must_fail "git pop stash@{1}" &&
+	test_must_fail "git apply stash@{1}" &&
+	test_must_fail "git show stash@{1}" &&
+	test_must_fail "git branch tmp stash@{1}" &&
+	git stash drop
+'
+
 test_done