t1400: add tests around adding/deleting pseudorefs

I have not been able to find any tests around adding pseudorefs using
`git update-ref`. Add some as outlined in this table (original design by
Michael Haggerty; modified and extended by me):

Pre-update value   | ref-update old OID   | Expected result
-------------------|----------------------|----------------
missing            | value                | reject
missing            | none given           | accept
set                | none given           | accept
set                | correct value        | accept
set                | wrong value          | reject
missing            | zero                 | accept *
set                | zero                 | reject *

The tests marked with a * currently fail, despite git-update-ref(1)
claiming that it is possible to "specify 40 '0' or an empty string as
<oldvalue> to make sure that the ref you are creating does not exist."
These failing tests will be fixed in the next commit.

It is only natural to test deletion as well. Test deletion without an
old OID, with a correct one and with an incorrect one.

Suggested-by: Michael Haggerty <[email protected]>
Signed-off-by: Martin Ågren <[email protected]>

Signed-off-by: Junio C Hamano <[email protected]>

Author: Martin Ågren

t/t1400-update-ref.sh

@@ -457,6 +457,66 @@ test_expect_success 'git cat-file blob master@{2005-05-26 23:42}:F (expect OTHER
 	test OTHER = $(git cat-file blob "master@{2005-05-26 23:42}:F")
 '
 
+# Test adding and deleting pseudorefs
+
+test_expect_success 'given old value for missing pseudoref, do not create' '
+	test_must_fail git update-ref PSEUDOREF $A $B 2>err &&
+	test_path_is_missing .git/PSEUDOREF &&
+	grep "could not read ref" err
+'
+
+test_expect_success 'create pseudoref' '
+	git update-ref PSEUDOREF $A &&
+	test $A = $(cat .git/PSEUDOREF)
+'
+
+test_expect_success 'overwrite pseudoref with no old value given' '
+	git update-ref PSEUDOREF $B &&
+	test $B = $(cat .git/PSEUDOREF)
+'
+
+test_expect_success 'overwrite pseudoref with correct old value' '
+	git update-ref PSEUDOREF $C $B &&
+	test $C = $(cat .git/PSEUDOREF)
+'
+
+test_expect_success 'do not overwrite pseudoref with wrong old value' '
+	test_must_fail git update-ref PSEUDOREF $D $E 2>err &&
+	test $C = $(cat .git/PSEUDOREF) &&
+	grep "unexpected object ID" err
+'
+
+test_expect_success 'delete pseudoref' '
+	git update-ref -d PSEUDOREF &&
+	test_path_is_missing .git/PSEUDOREF
+'
+
+test_expect_success 'do not delete pseudoref with wrong old value' '
+	git update-ref PSEUDOREF $A &&
+	test_must_fail git update-ref -d PSEUDOREF $B 2>err &&
+	test $A = $(cat .git/PSEUDOREF) &&
+	grep "unexpected object ID" err
+'
+
+test_expect_success 'delete pseudoref with correct old value' '
+	git update-ref -d PSEUDOREF $A &&
+	test_path_is_missing .git/PSEUDOREF
+'
+
+test_expect_failure 'create pseudoref with old OID zero' '
+	git update-ref PSEUDOREF $A $Z &&
+	test $A = $(cat .git/PSEUDOREF)
+'
+
+test_expect_failure 'do not overwrite pseudoref with old OID zero' '
+	test_when_finished git update-ref -d PSEUDOREF &&
+	test_must_fail git update-ref PSEUDOREF $B $Z 2>err &&
+	test $A = $(cat .git/PSEUDOREF) &&
+	grep "already exists" err
+'
+
+# Test --stdin
+
 a=refs/heads/a
 b=refs/heads/b
 c=refs/heads/c