t5520: test no merge candidates cases

a8c9bef (pull: improve advice for unconfigured error case, 2009-10-05)
fully established the current advices given by git-pull for the
different cases where git-fetch will not have anything marked for merge:

1. We fetched from a specific remote, and a refspec was given, but it
   ended up not fetching anything. This is usually because the user
   provided a wildcard refspec which had no matches on the remote end.

2. We fetched from a non-default remote, but didn't specify a branch to
   merge. We can't use the configured one because it applies to the
   default remote, and thus the user must specify the branches to merge.

3. We fetched from the branch's or repo's default remote, but:

   a. We are not on a branch, so there will never be a configured branch
      to merge with.

   b. We are on a branch, but there is no configured branch to merge
      with.

4. We fetched from the branch's or repo's default remote, but the
   configured branch to merge didn't get fetched (either it doesn't
   exist, or wasn't part of the configured fetch refspec)

Implement tests for the above 5 cases to ensure that the correct code
paths are triggered for each of these cases.

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

Author: pyokagan

t/t5520-pull.sh

@@ -109,6 +109,61 @@ test_expect_success 'the default remote . should not break explicit pull' '
 	test "$(cat file)" = modified
 '
 
+test_expect_success 'fail if wildcard spec does not match any refs' '
+	git checkout -b test copy^ &&
+	test_when_finished "git checkout -f copy && git branch -D test" &&
+	test "$(cat file)" = file &&
+	test_must_fail git pull . "refs/nonexisting1/*:refs/nonexisting2/*" 2>err &&
+	test_i18ngrep "no candidates for merging" err &&
+	test "$(cat file)" = file
+'
+
+test_expect_success 'fail if no branches specified with non-default remote' '
+	git remote add test_remote . &&
+	test_when_finished "git remote remove test_remote" &&
+	git checkout -b test copy^ &&
+	test_when_finished "git checkout -f copy && git branch -D test" &&
+	test "$(cat file)" = file &&
+	test_config branch.test.remote origin &&
+	test_must_fail git pull test_remote 2>err &&
+	test_i18ngrep "specify a branch on the command line" err &&
+	test "$(cat file)" = file
+'
+
+test_expect_success 'fail if not on a branch' '
+	git remote add origin . &&
+	test_when_finished "git remote remove origin" &&
+	git checkout HEAD^ &&
+	test_when_finished "git checkout -f copy" &&
+	test "$(cat file)" = file &&
+	test_must_fail git pull 2>err &&
+	test_i18ngrep "not currently on a branch" err &&
+	test "$(cat file)" = file
+'
+
+test_expect_success 'fail if no configuration for current branch' '
+	git remote add test_remote . &&
+	test_when_finished "git remote remove test_remote" &&
+	git checkout -b test copy^ &&
+	test_when_finished "git checkout -f copy && git branch -D test" &&
+	test_config branch.test.remote test_remote &&
+	test "$(cat file)" = file &&
+	test_must_fail git pull 2>err &&
+	test_i18ngrep "no tracking information" err &&
+	test "$(cat file)" = file
+'
+
+test_expect_success 'fail if upstream branch does not exist' '
+	git checkout -b test copy^ &&
+	test_when_finished "git checkout -f copy && git branch -D test" &&
+	test_config branch.test.remote . &&
+	test_config branch.test.merge refs/heads/nonexisting &&
+	test "$(cat file)" = file &&
+	test_must_fail git pull 2>err &&
+	test_i18ngrep "no such ref was fetched" err &&
+	test "$(cat file)" = file
+'
+
 test_expect_success '--rebase' '
 	git branch to-rebase &&
 	echo modified again > file &&