ref-filter: add test for --contains on a non-commit

Change the tag test suite to test for --contains on a tree & blob. It
only accepts commits and will spew out "<object> is a tree, not a
commit".

It's sufficient to test this just for the "tag" and "branch" commands,
because it covers all the machinery shared between "branch" and
"for-each-ref".

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

Author: avar

t/t3201-branch-contains.sh

@@ -130,6 +130,15 @@ test_expect_success 'implicit --list conflicts with modification options' '
 
 '
 
+test_expect_success 'Assert that --contains only works on commits, not trees & blobs' '
+	test_must_fail git branch --contains master^{tree} &&
+	blob=$(git hash-object -w --stdin <<-\EOF
+	Some blob
+	EOF
+	) &&
+	test_must_fail git branch --contains $blob
+'
+
 # We want to set up a case where the walk for the tracking info
 # of one branch crosses the tip of another branch (and make sure
 # that the latter walk does not mess up our flag to see if it was

t/t7004-tag.sh

@@ -1461,7 +1461,9 @@ test_expect_success 'mixing incompatibles modes and options is forbidden' '
 	test_must_fail git tag -n 100 &&
 	test_must_fail git tag -l -m msg &&
 	test_must_fail git tag -l -F some file &&
-	test_must_fail git tag -v -s
+	test_must_fail git tag -v -s &&
+	test_must_fail git tag --contains tag-tree &&
+	test_must_fail git tag --contains tag-blob
 '
 
 # check points-at