stash: add t3906 for submodule updates

Test that the stash apply command updates the work tree as expected for
changes which don't result in conflicts. To make that work add a helper
function that uses read-tree to apply the changes of the target commit
to the work tree, then stashes these changes and at last applies that
stash.

Implement the KNOWN_FAILURE_STASH_DOES_IGNORE_SUBMODULE_CHANGES switch
and reuse two other already present switches to expect the known
failure that stash does ignore submodule changes.

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

Author: jlehmann

t/lib-submodule-update.sh

@@ -227,7 +227,14 @@ test_submodule_switch () {
 	command="$1"
 	######################### Appearing submodule #########################
 	# Switching to a commit letting a submodule appear creates empty dir ...
-	test_expect_success "$command: added submodule creates empty directory" '
+	if test "$KNOWN_FAILURE_STASH_DOES_IGNORE_SUBMODULE_CHANGES" = 1
+	then
+		# Restoring stash fails to restore submodule index entry
+		RESULT="failure"
+	else
+		RESULT="success"
+	fi
+	test_expect_$RESULT "$command: added submodule creates empty directory" '
 		prolog &&
 		reset_work_tree_to no_submodule &&
 		(
@@ -241,7 +248,7 @@ test_submodule_switch () {
 		)
 	'
 	# ... and doesn't care if it already exists ...
-	test_expect_success "$command: added submodule leaves existing empty directory alone" '
+	test_expect_$RESULT "$command: added submodule leaves existing empty directory alone" '
 		prolog &&
 		reset_work_tree_to no_submodule &&
 		(
@@ -270,7 +277,7 @@ test_submodule_switch () {
 	'
 	# Replacing a tracked file with a submodule produces an empty
 	# directory ...
-	test_expect_success "$command: replace tracked file with submodule creates empty directory" '
+	test_expect_$RESULT "$command: replace tracked file with submodule creates empty directory" '
 		prolog &&
 		reset_work_tree_to replace_sub1_with_file &&
 		(
@@ -310,7 +317,13 @@ test_submodule_switch () {
 
 	######################## Disappearing submodule #######################
 	# Removing a submodule doesn't remove its work tree ...
-	test_expect_success "$command: removed submodule leaves submodule directory and its contents in place" '
+	if test "$KNOWN_FAILURE_STASH_DOES_IGNORE_SUBMODULE_CHANGES" = 1
+	then
+		RESULT="failure"
+	else
+		RESULT="success"
+	fi
+	test_expect_$RESULT "$command: removed submodule leaves submodule directory and its contents in place" '
 		prolog &&
 		reset_work_tree_to add_sub1 &&
 		(
@@ -322,7 +335,7 @@ test_submodule_switch () {
 		)
 	'
 	# ... especially when it contains a .git directory.
-	test_expect_success "$command: removed submodule leaves submodule containing a .git directory alone" '
+	test_expect_$RESULT "$command: removed submodule leaves submodule containing a .git directory alone" '
 		prolog &&
 		reset_work_tree_to add_sub1 &&
 		(

t/t3906-stash-submodule.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+test_description='stash apply can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+git_stash () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	git read-tree -u -m "$1" &&
+	git stash &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git stash apply
+}
+
+KNOWN_FAILURE_STASH_DOES_IGNORE_SUBMODULE_CHANGES=1
+KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+test_submodule_switch "git_stash"
+
+test_done