filter-trees: code clean-up of tests

A few trivial updates to test to match the current best practices.

 - avoid "grep -q" that strips potentially useful output from tests
   running under "-v".

 - use test_write_lines to prepare multi-line expected output file.

 - reserve use of test_must_fail to "git" commands.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5317-pack-objects-filter-objects.sh

@@ -69,7 +69,7 @@ test_expect_success 'get an error for missing tree object' '
 	test_must_fail git -C r5 pack-objects --rev --stdout 2>bad_tree <<-EOF &&
 	HEAD
 	EOF
-	grep -q "bad tree object" bad_tree
+	grep "bad tree object" bad_tree
 '
 
 test_expect_success 'setup for tests of tree:0' '

t/t5616-partial-clone.sh

@@ -192,7 +192,7 @@ test_expect_success 'use fsck before and after manually fetching a missing subtr
 	xargs -n1 git -C dst cat-file -t >fetched_types &&
 
 	sort -u fetched_types >unique_types.observed &&
-	printf "blob\ncommit\ntree\n" >unique_types.expected &&
+	test_write_lines blob commit tree >unique_types.expected &&
 	test_cmp unique_types.expected unique_types.observed
 '
 

t/t6112-rev-list-filters-objects.sh

@@ -38,8 +38,8 @@ test_expect_success 'specify blob explicitly prevents filtering' '
 		 awk -f print_2.awk) &&
 
 	git -C r1 rev-list --objects --filter=blob:none HEAD $file_3 >observed &&
-	grep -q "$file_3" observed &&
-	test_must_fail grep -q "$file_4" observed
+	grep "$file_3" observed &&
+	! grep "$file_4" observed
 '
 
 test_expect_success 'verify emitted+omitted == all' '
@@ -241,7 +241,7 @@ test_expect_success 'verify tree:0 includes trees in "filtered" output' '
 	xargs -n1 git -C r3 cat-file -t >unsorted_filtered_types &&
 
 	sort -u unsorted_filtered_types >filtered_types &&
-	printf "blob\ntree\n" >expected &&
+	test_write_lines blob tree >expected &&
 	test_cmp expected filtered_types
 '