[PATCH 08/16] t5304: use helper to report failure of "test foo = bar"

[Jeff King <peff@peff.net>]

For small outputs, we sometimes use:

  test "$(some_cmd)" = "something we expect"

instead of a full test_cmp. The downside of this is that
when it fails, there is no output at all from the script.
Let's introduce a small helper to make tests easier to
debug.

Signed-off-by: Jeff King <peff@peff.net>
---
This is in the same boat as the last commit; we can drop it without
hurting the rest of the series.

Is test_eq too cutesy or obfuscated? I have often wanted it when
debugging other tests, too. Our usual technique is to do:

  echo whatever >expect &&
  do_something >actual &&
  test_cmp expect actual

That's a bit verbose. We could hide it behind something like test_eq,
too, but it introduces several extra new processes. And I know people on
some fork-challenged platforms are very sensitive to the number of
spawned processes in the test suite.

 t/t5304-prune.sh        | 16 ++++++++--------
 t/test-lib-functions.sh | 11 +++++++++++
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/t/t5304-prune.sh b/t/t5304-prune.sh
index b0ffb05..502860e 100755
--- a/t/t5304-prune.sh
+++ b/t/t5304-prune.sh
@@ -13,7 +13,7 @@ add_blob() {
 	before=$(git count-objects | sed "s/ .*//") &&
 	BLOB=$(echo aleph_0 | git hash-object -w --stdin) &&
 	BLOB_FILE=.git/objects/$(echo $BLOB | sed "s/^../&\//") &&
-	test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
+	test_eq $((1 + $before)) $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE &&
 	test-chmtime =+0 $BLOB_FILE
 }
@@ -45,11 +45,11 @@ test_expect_success 'prune --expire' '
 
 	add_blob &&
 	git prune --expire=1.hour.ago &&
-	test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
+	test_eq $((1 + $before)) $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE &&
 	test-chmtime =-86500 $BLOB_FILE &&
 	git prune --expire 1.day &&
-	test $before = $(git count-objects | sed "s/ .*//") &&
+	test_eq $before $(git count-objects | sed "s/ .*//") &&
 	test_path_is_missing $BLOB_FILE
 
 '
@@ -59,11 +59,11 @@ test_expect_success 'gc: implicit prune --expire' '
 	add_blob &&
 	test-chmtime =-$((2*$week-30)) $BLOB_FILE &&
 	git gc &&
-	test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
+	test_eq $((1 + $before)) $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE &&
 	test-chmtime =-$((2*$week+1)) $BLOB_FILE &&
 	git gc &&
-	test $before = $(git count-objects | sed "s/ .*//") &&
+	test_eq $before $(git count-objects | sed "s/ .*//") &&
 	test_path_is_missing $BLOB_FILE
 
 '
@@ -144,7 +144,7 @@ test_expect_success 'gc --no-prune' '
 	test-chmtime =-$((5001*$day)) $BLOB_FILE &&
 	git config gc.pruneExpire 2.days.ago &&
 	git gc --no-prune &&
-	test 1 = $(git count-objects | sed "s/ .*//") &&
+	test_eq 1 $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE
 
 '
@@ -209,10 +209,10 @@ test_expect_success 'gc: prune old objects after local clone' '
 	git clone --no-hardlinks . aclone &&
 	(
 		cd aclone &&
-		test 1 = $(git count-objects | sed "s/ .*//") &&
+		test_eq 1 $(git count-objects | sed "s/ .*//") &&
 		test_path_is_file $BLOB_FILE &&
 		git gc --prune &&
-		test 0 = $(git count-objects | sed "s/ .*//") &&
+		test_eq 0 $(git count-objects | sed "s/ .*//") &&
 		test_path_is_missing $BLOB_FILE
 	)
 '
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index dafd6ad..0a17614 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -634,6 +634,17 @@ test_cmp_bin() {
 	cmp "$@"
 }
 
+# This is the same as 'test "$1" $3 "$2"' except that it
+# will output a useful message to stderr on failure. If
+# $3 is omitted, defaults to "=".
+test_eq () {
+	if ! test "$1" "${3:-=}" "$2"
+	then
+		echo >&2 "test_eq failed: $1 ${3:-=} $2"
+		false
+	fi
+}
+
 # Check if the file expected to be empty is indeed empty, and barfs
 # otherwise.
 
-- 
2.1.1.566.gdb1f904