[PATCH v2] t4150: fix broken test for am --scissors

[Andrei Rybak <rybak.a.v@gmail.com>]

Tests for "git am --[no-]scissors" [1] work in the following way:

 1. Create files with commit messages
 2. Use these files to create expected commits
 3. Generate eml file with patch from expected commits
 4. Create commits using git am with these eml files
 5. Compare these commits with expected

The test for "git am --scissors" is supposed to take a message with a
scissors line and demonstrate that the subject line from the e-mail
itself is overridden by the in-body "Subject:" header and that only text
below the scissors line is included in the commit message of the commit
created by the invocation of "git am --scissors". However, the setup of
the test incorrectly uses a commit without the scissors line and in-body
"Subject:" header in the commit message, and thus, creates eml file not
suitable for testing of "git am --scissors".

This can be checked by intentionally breaking is_scissors_line function
in mailinfo.c, for example, by changing string ">8", which is used by
the test. With such change the test should fail, but does not.

Fix broken test by generating eml file with scissors line and in-body
header "Subject:". Since the two tests for --scissors and --no-scissors
options are there to test cutting or keeping the commit message, update
both tests to change the test file in the same way, which allows us to
generate only one eml file to be passed to git am. To clarify the
intention of the test, give files and tags more explicit names.

[1]: introduced in bf72ac17d (t4150: tests for am --[no-]scissors,
     2015-07-19)

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
---

Applies on top of 980a3d3dd (Merge branch 'pt/am-tests', 2015-08-03).
This patch is also available at

  https://github.com/rybak/git fix-am-scissors-test-v2

Changes since v1:

 - Reword commit message after feedback from Junio
 - Keep the empty line under scissors in the test e-mail, as it does not
   affect the test

 t/t4150-am.sh | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index e9b6f8158..bb2d951a7 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -67,13 +67,15 @@ test_expect_success 'setup: messages' '
 
 	EOF
 
-	cat >scissors-msg <<-\EOF &&
-	Test git-am with scissors line
+	cat >msg-without-scissors-line <<-\EOF &&
+	Test that git-am --scissors cuts at the scissors line
 
 	This line should be included in the commit message.
 	EOF
 
-	cat - scissors-msg >no-scissors-msg <<-\EOF &&
+	printf "Subject: " >subject-prefix &&
+
+	cat - subject-prefix msg-without-scissors-line >msg-with-scissors-line <<-\EOF &&
 	This line should not be included in the commit message with --scissors enabled.
 
 	 - - >8 - - remove everything above this line - - >8 - -
@@ -150,18 +152,17 @@ test_expect_success setup '
 	} >patch1-hg.eml &&
 
 
-	echo scissors-file >scissors-file &&
-	git add scissors-file &&
-	git commit -F scissors-msg &&
-	git tag scissors &&
-	git format-patch --stdout scissors^ >scissors-patch.eml &&
+	echo file >file &&
+	git add file &&
+	git commit -F msg-without-scissors-line &&
+	git tag scissors-used &&
 	git reset --hard HEAD^ &&
 
-	echo no-scissors-file >no-scissors-file &&
-	git add no-scissors-file &&
-	git commit -F no-scissors-msg &&
-	git tag no-scissors &&
-	git format-patch --stdout no-scissors^ >no-scissors-patch.eml &&
+	echo file >file &&
+	git add file &&
+	git commit -F msg-with-scissors-line &&
+	git tag scissors-not-used &&
+	git format-patch --stdout scissors-not-used^ >patch-with-scissors-line.eml &&
 	git reset --hard HEAD^ &&
 
 	sed -n -e "3,\$p" msg >file &&
@@ -418,10 +419,10 @@ test_expect_success 'am --scissors cuts the message at the scissors line' '
 	rm -fr .git/rebase-apply &&
 	git reset --hard &&
 	git checkout second &&
-	git am --scissors scissors-patch.eml &&
+	git am --scissors patch-with-scissors-line.eml &&
 	test_path_is_missing .git/rebase-apply &&
-	git diff --exit-code scissors &&
-	test_cmp_rev scissors HEAD
+	git diff --exit-code scissors-used &&
+	test_cmp_rev scissors-used HEAD
 '
 
 test_expect_success 'am --no-scissors overrides mailinfo.scissors' '
@@ -429,10 +430,10 @@ test_expect_success 'am --no-scissors overrides mailinfo.scissors' '
 	git reset --hard &&
 	git checkout second &&
 	test_config mailinfo.scissors true &&
-	git am --no-scissors no-scissors-patch.eml &&
+	git am --no-scissors patch-with-scissors-line.eml &&
 	test_path_is_missing .git/rebase-apply &&
-	git diff --exit-code no-scissors &&
-	test_cmp_rev no-scissors HEAD
+	git diff --exit-code scissors-not-used &&
+	test_cmp_rev scissors-not-used HEAD
 '
 
 test_expect_success 'setup: new author and committer' '
-- 
2.18.0