t7501: stop losing return codes of git commands

In a pipe, only the return code of the last command is used. Thus, all
other commands will have their return codes masked. Rewrite pipes so
that there are no git commands upstream so that we will know if a
command fails.

In the 'interactive add' test case, we prepend a `test_must_fail` to
`git commit --interactive`. When there are no changes to commit,
`git commit` will exit with status code 1. Following along with the rest
of the file, we use `test_must_fail` to test for this case.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7501-commit-basic-functionality.sh b/t/t7501-commit-basic-functionality.sh
index 5765d33..110b4bf 100755
--- a/t/t7501-commit-basic-functionality.sh
+++ b/t/t7501-commit-basic-functionality.sh
@@ -285,9 +285,8 @@
 '
 
 test_expect_success PERL 'interactive add' '
-	echo 7 |
-	git commit --interactive |
-	grep "What now"
+	echo 7 | test_must_fail git commit --interactive >out &&
+	grep "What now" out
 '
 
 test_expect_success PERL "commit --interactive doesn't change index if editor aborts" '
@@ -362,10 +361,10 @@
 	oldtick=$GIT_AUTHOR_DATE &&
 	test_tick &&
 	git reset --hard &&
-	git cat-file -p HEAD |
+	git cat-file -p HEAD >commit &&
 	sed -e "s/author.*/author $author $oldtick/" \
-		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" > \
-		expected &&
+		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" \
+		commit >expected &&
 	git commit --amend --author="$author" &&
 	git cat-file -p HEAD >current &&
 	test_cmp expected current
@@ -377,10 +376,10 @@
 	test_tick &&
 	newtick=$GIT_AUTHOR_DATE &&
 	git reset --hard &&
-	git cat-file -p HEAD |
+	git cat-file -p HEAD >commit &&
 	sed -e "s/author.*/author $author $newtick/" \
-		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" > \
-		expected &&
+		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" \
+		commit >expected &&
 	git commit --amend --date="$newtick" &&
 	git cat-file -p HEAD >current &&
 	test_cmp expected current
@@ -409,12 +408,13 @@
 	echo 1 >positive &&
 	git add positive &&
 	git commit -s -m "thank you" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo thank you &&
 		echo &&
-		git var GIT_COMMITTER_IDENT |
-		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /"
+		git var GIT_COMMITTER_IDENT >ident &&
+		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /" ident
 	) >expected &&
 	test_cmp expected actual
 
@@ -428,13 +428,14 @@
 	git commit -s -m "thank you
 
 $existing" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo thank you &&
 		echo &&
 		echo $existing &&
-		git var GIT_COMMITTER_IDENT |
-		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /"
+		git var GIT_COMMITTER_IDENT >ident &&
+		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /" ident
 	) >expected &&
 	test_cmp expected actual
 
@@ -448,13 +449,14 @@
 	git commit -s -m "welcome
 
 $alt" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo welcome &&
 		echo &&
 		echo $alt &&
-		git var GIT_COMMITTER_IDENT |
-		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /"
+		git var GIT_COMMITTER_IDENT >ident &&
+		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /" ident
 	) >expected &&
 	test_cmp expected actual
 '
@@ -468,15 +470,16 @@
 
 We have now
 $alt" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo welcome &&
 		echo &&
 		echo We have now &&
 		echo $alt &&
 		echo &&
-		git var GIT_COMMITTER_IDENT |
-		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /"
+		git var GIT_COMMITTER_IDENT >ident &&
+		sed -e "s/>.*/>/" -e "s/^/Signed-off-by: /" ident
 	) >expected &&
 	test_cmp expected actual
 '
@@ -489,7 +492,8 @@
 
 non-trailer line
 Myfooter: x" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo subject &&
 		echo &&
@@ -506,7 +510,8 @@
 
 non-trailer line
 Myfooter: x" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo subject &&
 		echo &&
@@ -538,7 +543,8 @@
 	>negative &&
 	git add negative &&
 	git commit -m "one" -m "two" -m "three" &&
-	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	git cat-file commit HEAD >commit &&
+	sed -e "1,/^\$/d" commit >actual &&
 	(
 		echo one &&
 		echo &&
@@ -555,10 +561,10 @@
 	oldtick=$GIT_AUTHOR_DATE &&
 	test_tick &&
 	git reset --hard &&
-	git cat-file -p HEAD |
+	git cat-file -p HEAD >commit &&
 	sed -e "s/author.*/author $author $oldtick/" \
-		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" > \
-		expected &&
+		-e "s/^\(committer.*> \).*$/\1$GIT_COMMITTER_DATE/" \
+		commit >expected &&
 	git commit --amend --author="$author" &&
 	git cat-file -p HEAD >current &&
 	test_cmp expected current
@@ -570,8 +576,10 @@
 	echo tehlulz >chz &&
 	git add chz &&
 	git commit elif -m "tacocat is a palindrome" &&
-	git show --stat | grep elif &&
-	git diff --cached | grep chz
+	git show --stat >stat &&
+	grep elif stat &&
+	git diff --cached >diff &&
+	grep chz diff
 '
 
 test_expect_success 'same tree (single parent)' '
@@ -584,7 +592,8 @@
 test_expect_success 'same tree (single parent) --allow-empty' '
 
 	git commit --allow-empty -m "forced empty" &&
-	git cat-file commit HEAD | grep forced
+	git cat-file commit HEAD >commit &&
+	grep forced commit
 
 '