t6424: make sure a failed merge preserves local changes

We do make sure that an attempt to merge with various forms of local
changes will "fail", but the point of stopping the merge is so that
we refrain from discarding uncommitted local changes that could be
precious.  Add a few more checks for each case to make sure the
local changes are left intact.

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

t/t6424-merge-unrelated-index-changes.sh

@@ -71,7 +71,9 @@ test_expect_success 'ff update' '
 	git merge E^0 &&
 
 	test_must_fail git rev-parse HEAD:random_file &&
-	test "$(git diff --name-only --cached E)" = "random_file"
+	test "$(git diff --name-only --cached E)" = "random_file" &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file
 '
 
 test_expect_success 'ff update, important file modified' '
@@ -83,6 +85,8 @@ test_expect_success 'ff update, important file modified' '
 	git add subdir/e &&
 
 	test_must_fail git merge E^0 &&
+	test_path_is_file subdir/e &&
+	git rev-parse --verify :subdir/e &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -93,6 +97,8 @@ test_expect_success 'resolve, trivial' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge -s resolve C^0 &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -103,6 +109,8 @@ test_expect_success 'resolve, non-trivial' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge -s resolve D^0 &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -113,6 +121,8 @@ test_expect_success 'recursive' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge -s recursive C^0 &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -145,9 +155,12 @@ test_expect_success 'recursive, when file has staged changes not matching HEAD n
 	mkdir subdir &&
 	test_seq 1 10 >subdir/a &&
 	git add subdir/a &&
+	git rev-parse --verify :subdir/a >expect &&
 
 	# We have staged changes; merge should error out
 	test_must_fail git merge -s recursive E^0 2>err &&
+	git rev-parse --verify :subdir/a >actual &&
+	test_cmp expect actual &&
 	test_i18ngrep "changes to the following files would be overwritten" err
 '
 
@@ -158,9 +171,12 @@ test_expect_success 'recursive, when file has staged changes matching what a mer
 	mkdir subdir &&
 	test_seq 1 11 >subdir/a &&
 	git add subdir/a &&
+	git rev-parse --verify :subdir/a >expect &&
 
 	# We have staged changes; merge should error out
 	test_must_fail git merge -s recursive E^0 2>err &&
+	git rev-parse --verify :subdir/a >actual &&
+	test_cmp expect actual &&
 	test_i18ngrep "changes to the following files would be overwritten" err
 '
 
@@ -171,7 +187,9 @@ test_expect_success 'octopus, unrelated file touched' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge C^0 D^0 &&
-	test_path_is_missing .git/MERGE_HEAD
+	test_path_is_missing .git/MERGE_HEAD &&
+	git rev-parse --verify :random_file &&
+	test_path_exists random_file
 '
 
 test_expect_success 'octopus, related file removed' '
@@ -181,6 +199,8 @@ test_expect_success 'octopus, related file removed' '
 	git rm b &&
 
 	test_must_fail git merge C^0 D^0 &&
+	test_path_is_missing b &&
+	test_must_fail git rev-parse --verify :b &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -189,8 +209,12 @@ test_expect_success 'octopus, related file modified' '
 	git checkout B^0 &&
 
 	echo 12 >>a && git add a &&
+	git rev-parse --verify :a >expect &&
 
 	test_must_fail git merge C^0 D^0 &&
+	test_path_is_file a &&
+	git rev-parse --verify :a >actual &&
+	test_cmp expect actual &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -201,6 +225,8 @@ test_expect_success 'ours' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge -s ours C^0 &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file &&
 	test_path_is_missing .git/MERGE_HEAD
 '
 
@@ -211,6 +237,8 @@ test_expect_success 'subtree' '
 	touch random_file && git add random_file &&
 
 	test_must_fail git merge -s subtree E^0 &&
+	test_path_is_file random_file &&
+	git rev-parse --verify :random_file &&
 	test_path_is_missing .git/MERGE_HEAD
 '