Merge branch 'mm/add-p-split-error'

When "add--interactive" splits a hunk into two overlapping hunks
and then let the user choose only one, it sometimes feeds an
incorrect patch text to "git apply".  Add tests to demonstrate
this.

I have a slight suspicion that this may be $gmane/87202 coming back
and biting us (I seem to have said "let's run with this and see
what happens" back then).

* mm/add-p-split-error:
  stash -p: demonstrate failure of split with mixed y/n
  t3904-stash-patch: factor PERL prereq at the top of the file
  t3904-stash-patch: fix test description
  add -p: demonstrate failure when running 'edit' after a split
  t3701-add-interactive: simplify code

Author: gitster

t/t3701-add-interactive.sh

@@ -326,15 +326,34 @@ test_expect_success 'split hunk "add -p (edit)"' '
 	# 2. Correct version applies the (not)edited version, and asks
 	#    about the next hunk, against which we say q and program
 	#    exits.
-	for a in s e     q n q q
-	do
-		echo $a
-	done |
+	printf "%s\n" s e     q n q q |
 	EDITOR=: git add -p &&
 	git diff >actual &&
 	! grep "^+15" actual
 '
 
+test_expect_failure 'split hunk "add -p (no, yes, edit)"' '
+	cat >test <<-\EOF &&
+	5
+	10
+	20
+	21
+	30
+	31
+	40
+	50
+	60
+	EOF
+	git reset &&
+	# test sequence is s(plit), n(o), y(es), e(dit)
+	# q n q q is there to make sure we exit at the end.
+	printf "%s\n" s n y e   q n q q |
+	EDITOR=: git add -p 2>error &&
+	test_must_be_empty error &&
+	git diff >actual &&
+	! grep "^+31" actual
+'
+
 test_expect_success 'patch mode ignores unmerged entries' '
 	git reset --hard &&
 	test_commit conflict &&

t/t3904-stash-patch.sh

@@ -1,9 +1,15 @@
 #!/bin/sh
 
-test_description='git checkout --patch'
+test_description='stash -p'
 . ./lib-patch-mode.sh
 
-test_expect_success PERL 'setup' '
+if ! test_have_prereq PERL
+then
+	skip_all='skipping stash -p tests, perl not available'
+	test_done
+fi
+
+test_expect_success 'setup' '
 	mkdir dir &&
 	echo parent > dir/foo &&
 	echo dummy > bar &&
@@ -20,7 +26,7 @@ test_expect_success PERL 'setup' '
 
 # note: order of files with unstaged changes: HEAD bar dir/foo
 
-test_expect_success PERL 'saying "n" does nothing' '
+test_expect_success 'saying "n" does nothing' '
 	set_state HEAD HEADfile_work HEADfile_index &&
 	set_state dir/foo work index &&
 	(echo n; echo n; echo n) | test_must_fail git stash save -p &&
@@ -29,7 +35,7 @@ test_expect_success PERL 'saying "n" does nothing' '
 	verify_state dir/foo work index
 '
 
-test_expect_success PERL 'git stash -p' '
+test_expect_success 'git stash -p' '
 	(echo y; echo n; echo y) | git stash save -p &&
 	verify_state HEAD committed HEADfile_index &&
 	verify_saved_state bar &&
@@ -41,7 +47,7 @@ test_expect_success PERL 'git stash -p' '
 	verify_state dir/foo work head
 '
 
-test_expect_success PERL 'git stash -p --no-keep-index' '
+test_expect_success 'git stash -p --no-keep-index' '
 	set_state HEAD HEADfile_work HEADfile_index &&
 	set_state bar bar_work bar_index &&
 	set_state dir/foo work index &&
@@ -56,7 +62,7 @@ test_expect_success PERL 'git stash -p --no-keep-index' '
 	verify_state dir/foo work index
 '
 
-test_expect_success PERL 'git stash --no-keep-index -p' '
+test_expect_success 'git stash --no-keep-index -p' '
 	set_state HEAD HEADfile_work HEADfile_index &&
 	set_state bar bar_work bar_index &&
 	set_state dir/foo work index &&
@@ -71,8 +77,31 @@ test_expect_success PERL 'git stash --no-keep-index -p' '
 	verify_state dir/foo work index
 '
 
-test_expect_success PERL 'none of this moved HEAD' '
+test_expect_success 'none of this moved HEAD' '
 	verify_saved_head
 '
 
+test_expect_failure 'stash -p with split hunk' '
+	git reset --hard &&
+	cat >test <<-\EOF &&
+	aaa
+	bbb
+	ccc
+	EOF
+	git add test &&
+	git commit -m "initial" &&
+	cat >test <<-\EOF &&
+	aaa
+	added line 1
+	bbb
+	added line 2
+	ccc
+	EOF
+	printf "%s\n" s n y q |
+	test_might_fail git stash -p 2>error &&
+	! test_must_be_empty error &&
+	grep "added line 1" test &&
+	! grep "added line 2" test
+'
+
 test_done