t4104: modernize and simplify quoting

Drop whitespace in the value of `$test_description` and in a test body
and use `test_write_lines`.

Stop defining `$u` with a trailing space just so that we can tuck it in
like `git foo $u$more...` and get minimal whitespace in the command:
`git foo $u $more...` is more readable at the "cost" of an empty `$u`
yielding `git foo  something...`.

Finally, avoid using single quotes within the test scripts to repeatedly
close and reopen the quotes that wrap the test scripts (see the previous
commit). This "unnecessary" quoting does mean that the verbose test
output shows the interpolated values, i.e., the shell code we're
running. But the downside is that the source of the script does *not*
show the shell code we're eventually executing, leaving the reader to
reason about what we really do and whether there are any quoting issues.
(There aren't.)

Where we run through loops to generate several "identical but different"
tests, the test message contains the interpolated variables we're
looping on, meaning one can always identify exactly which instance has
failed, even if the verbose test output shows the exact same test body
several times.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4104-apply-boundary.sh

@@ -3,80 +3,55 @@
 # Copyright (c) 2005 Junio C Hamano
 #
 
-test_description='git apply boundary tests
+test_description='git apply boundary tests'
 
-'
 . ./test-lib.sh
 
 L="c d e f g h i j k l m n o p q r s t u v w x"
 
 test_expect_success setup '
-	for i in b '"$L"' y
+	test_write_lines b $L y >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >original &&
 	git update-index --add victim &&
 
 	# add to the head
-	for i in a b '"$L"' y
+	test_write_lines a b $L y >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >add-a-expect &&
 	git diff victim >add-a-patch.with &&
 	git diff --unified=0 >add-a-patch.without &&
 
 	# insert at line two
-	for i in b a '"$L"' y
+	test_write_lines b a $L y >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >insert-a-expect &&
 	git diff victim >insert-a-patch.with &&
 	git diff --unified=0 >insert-a-patch.without &&
 
 	# modify at the head
-	for i in a '"$L"' y
+	test_write_lines a $L y >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >mod-a-expect &&
 	git diff victim >mod-a-patch.with &&
 	git diff --unified=0 >mod-a-patch.without &&
 
 	# remove from the head
-	for i in '"$L"' y
+	test_write_lines $L y >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >del-a-expect &&
 	git diff victim >del-a-patch.with &&
 	git diff --unified=0 >del-a-patch.without &&
 
 	# add to the tail
-	for i in b '"$L"' y z
+	test_write_lines b $L y z >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >add-z-expect &&
 	git diff victim >add-z-patch.with &&
 	git diff --unified=0 >add-z-patch.without &&
 
 	# modify at the tail
-	for i in b '"$L"' z
+	test_write_lines b $L z >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >mod-z-expect &&
 	git diff victim >mod-z-patch.with &&
 	git diff --unified=0 >mod-z-patch.without &&
 
 	# remove from the tail
-	for i in b '"$L"'
+	test_write_lines b $L >victim &&
-	do
-		echo $i
-	done >victim &&
 	cat victim >del-z-expect &&
 	git diff victim >del-z-patch.with &&
 	git diff --unified=0 >del-z-patch.without
@@ -88,15 +63,15 @@ for with in with without
 do
 	case "$with" in
 	with) u= ;;
-	without) u='--unidiff-zero ' ;;
+	without) u=--unidiff-zero ;;
 	esac
 	for kind in add-a add-z insert-a mod-a mod-z del-a del-z
 	do
 		test_expect_success "apply $kind-patch $with context" '
 			cat original >victim &&
 			git update-index victim &&
-			git apply --index '"$u$kind-patch.$with"' &&
+			git apply --index $u "$kind-patch.$with" &&
-			test_cmp '"$kind"'-expect victim
+			test_cmp "$kind-expect" victim
 		'
 	done
 done
@@ -110,13 +85,12 @@ do
 	test_expect_success "apply non-git $kind-patch without context" '
 		cat original >victim &&
 		git update-index victim &&
-		git apply --unidiff-zero --index '"$kind-ng.without"' &&
+		git apply --unidiff-zero --index "$kind-ng.without" &&
-		test_cmp '"$kind"'-expect victim
+		test_cmp "$kind-expect" victim
 	'
 done
 
 test_expect_success 'two lines' '
-
 	>file &&
 	git add file &&
 	echo aaa >file &&
@@ -125,11 +99,10 @@ test_expect_success 'two lines' '
 	echo bbb >file &&
 	git add file &&
 	test_must_fail git apply --check patch
-
 '
 
 test_expect_success 'apply patch with 3 context lines matching at end' '
-	{ echo a; echo b; echo c; echo d; } >file &&
+	test_write_lines a b c d >file &&
 	git add file &&
 	echo e >>file &&
 	git diff >patch &&