Teach read-tree the -n|--dry-run option

The option can be used to check if read-tree with the same set of other
options like "-m" and "-u" would succeed without actually changing either
the index or the working tree.

The relevant tests in the t10?? range were extended to do a read-tree -n
before the real read-tree to make sure neither the index nor any local
files were changed with -n and the same exit code as without -n is
returned. The helper functions added for that purpose reside in the new
t/lib-read-tree.sh file.

The only exception is #13 in t1004 ("unlinking an un-unlink-able
symlink"). As this is an issue of wrong directory permissions it is not
detected with -n.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/t/t1005-read-tree-reset.sh b/t/t1005-read-tree-reset.sh
index 849911683a..f53de79e56 100755
--- a/t/t1005-read-tree-reset.sh
+++ b/t/t1005-read-tree-reset.sh
@@ -3,6 +3,7 @@
 test_description='read-tree -u --reset'
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-read-tree.sh
 
 # two-tree test
 
@@ -22,13 +23,13 @@ test_expect_success 'setup' '
 '
 
 test_expect_success 'reset should work' '
-  git read-tree -u --reset HEAD^ &&
+  read_tree_u_must_succeed -u --reset HEAD^ &&
   git ls-files >actual &&
   test_cmp expect actual
 '
 
 test_expect_success 'reset should remove remnants from a failed merge' '
-  git read-tree --reset -u HEAD &&
+  read_tree_u_must_succeed --reset -u HEAD &&
   git ls-files -s >expect &&
   sha1=$(git rev-parse :new) &&
   (
@@ -37,13 +38,13 @@ test_expect_success 'reset should remove remnants from a failed merge' '
   ) | git update-index --index-info &&
   >old &&
   git ls-files -s &&
-  git read-tree --reset -u HEAD &&
+  read_tree_u_must_succeed --reset -u HEAD &&
   git ls-files -s >actual &&
   ! test -f old
 '
 
 test_expect_success 'Porcelain reset should remove remnants too' '
-  git read-tree --reset -u HEAD &&
+  read_tree_u_must_succeed --reset -u HEAD &&
   git ls-files -s >expect &&
   sha1=$(git rev-parse :new) &&
   (
@@ -58,7 +59,7 @@ test_expect_success 'Porcelain reset should remove remnants too' '
 '
 
 test_expect_success 'Porcelain checkout -f should remove remnants too' '
-  git read-tree --reset -u HEAD &&
+  read_tree_u_must_succeed --reset -u HEAD &&
   git ls-files -s >expect &&
   sha1=$(git rev-parse :new) &&
   (
@@ -73,7 +74,7 @@ test_expect_success 'Porcelain checkout -f should remove remnants too' '
 '
 
 test_expect_success 'Porcelain checkout -f HEAD should remove remnants too' '
-  git read-tree --reset -u HEAD &&
+  read_tree_u_must_succeed --reset -u HEAD &&
   git ls-files -s >expect &&
   sha1=$(git rev-parse :new) &&
   (