t5516: more tests for receive.denyCurrentBranch=updateInstead

The previous one tests only the case where a path to be updated by
the push-to-deploy has an incompatible change in the target's
working tree that has already been added to the index, but the
feature itself wants to require the working tree to be a lot cleaner
than what is tested.  Add a handful more tests to protect the
feature from future changes that mistakenly (from the viewpoint of
the inventor of the feature) loosens the cleanliness requirement,
namely:

 - A change only to the working tree but not to the index is still a
   change to be protected;

 - An untracked file in the working tree that would be overwritten
   by a push-to-deploy needs to be protected;

 - A change that happens to make a file identical to what is being
   pushed is still a change to be protected (i.e. the feature's
   cleanliness requirement is more strict than that of checkout).

Also, test that a stat-only change to the working tree is not a
reason to reject a push-to-deploy.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5516-fetch-push.sh

@@ -1332,28 +1332,106 @@ test_expect_success 'fetch into bare respects core.logallrefupdates' '
 
 test_expect_success 'receive.denyCurrentBranch = updateInstead' '
 	git push testrepo master &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
 		git reset --hard &&
 		git config receive.denyCurrentBranch updateInstead
 	) &&
 	test_commit third path2 &&
+
+	# Try pushing into a repository with pristine working tree
 	git push testrepo master &&
-	test $(git rev-parse HEAD) = $(cd testrepo && git rev-parse HEAD) &&
-	test third = "$(cat testrepo/path2)" &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
+		git update-index -q --refresh &&
+		git diff-files --quiet -- &&
+		git diff-index --quiet --cached HEAD -- &&
+		test third = "$(cat path2)" &&
+		test $(git -C .. rev-parse HEAD) = $(git rev-parse HEAD)
+	) &&
+
+	# Try pushing into a repository with working tree needing a refresh
+	(
+		cd testrepo &&
+		git reset --hard HEAD^ &&
+		test $(git -C .. rev-parse HEAD^) = $(git rev-parse HEAD) &&
+		test-chmtime +100 path1
+	) &&
+	git push testrepo master &&
+	(
+		cd testrepo &&
 		git update-index -q --refresh &&
 		git diff-files --quiet -- &&
 		git diff-index --quiet --cached HEAD -- &&
-		echo changed >path2 &&
-		git add path2
+		test_cmp ../path1 path1 &&
+		test third = "$(cat path2)" &&
+		test $(git -C .. rev-parse HEAD) = $(git rev-parse HEAD)
 	) &&
+
+	# Update what is to be pushed
 	test_commit fourth path2 &&
+
+	# Try pushing into a repository with a dirty working tree
+	# (1) the working tree updated
+	(
+		cd testrepo &&
+		echo changed >path1
+	) &&
 	test_must_fail git push testrepo master &&
-	test $(git rev-parse HEAD^) = $(git -C testrepo rev-parse HEAD) &&
-	(cd testrepo &&
+	(
+		cd testrepo &&
+		test $(git -C .. rev-parse HEAD^) = $(git rev-parse HEAD) &&
+		git diff --quiet --cached &&
+		test changed = "$(cat path1)"
+	) &&
+
+	# (2) the index updated
+	(
+		cd testrepo &&
+		echo changed >path1 &&
+		git add path1
+	) &&
+	test_must_fail git push testrepo master &&
+	(
+		cd testrepo &&
+		test $(git -C .. rev-parse HEAD^) = $(git rev-parse HEAD) &&
+		git diff --quiet &&
+		test changed = "$(cat path1)"
+	) &&
+
+	# Introduce a new file in the update
+	test_commit fifth path3 &&
+
+	# (3) the working tree has an untracked file that would interfere
+	(
+		cd testrepo &&
+		git reset --hard &&
+		echo changed >path3
+	) &&
+	test_must_fail git push testrepo master &&
+	(
+		cd testrepo &&
+		test $(git -C .. rev-parse HEAD^^) = $(git rev-parse HEAD) &&
+		git diff --quiet &&
+		git diff --quiet --cached &&
+		test changed = "$(cat path3)"
+	) &&
+
+	# (4) the target changes to what gets pushed but it still is a change
+	(
+		cd testrepo &&
+		git reset --hard &&
+		echo fifth >path3 &&
+		git add path3
+	) &&
+	test_must_fail git push testrepo master &&
+	(
+		cd testrepo &&
+		test $(git -C .. rev-parse HEAD^^) = $(git rev-parse HEAD) &&
 		git diff --quiet &&
-		test changed = "$(cat path2)"
+		test fifth = "$(cat path3)"
 	)
+
 '
 
 test_done