[PATCH] tests: improve diagnostics when asserting empty files

[Pádraig Brady]

* tests/chmod/c-option.sh: Use `compare /dev/null ... || fail=1`
rather than `test -s ... && fail=1`, so that the file contents
are output, thus improving diagnostics for failing tests.
* tests/cp/cp-a-selinux.sh: Likewise.
* tests/cp/cp-mv-enotsup-xattr.sh: Likewise.
* tests/dd/misc.sh: Likewise.
* tests/misc/nice.sh: Likewise.
* tests/misc/xattr.sh: Likewise.
* tests/mv/update.sh: Likewise.
* tests/rm/deep-2.sh: Likewise.
* tests/rm/read-only.sh: Likewise.
* tests/split/r-chunk.sh: Likewise.
* tests/tail-2/follow-stdin.sh: Likewise.
* tests/tail-2/wait.sh: Likewise.
* tests/touch/no-dereference.sh: Likewise.
---
 tests/chmod/c-option.sh         |    2 +-
 tests/cp/cp-a-selinux.sh        |    5 +++--
 tests/cp/cp-mv-enotsup-xattr.sh |    8 ++++----
 tests/dd/misc.sh                |    6 +++---
 tests/misc/nice.sh              |    2 +-
 tests/misc/xattr.sh             |    2 +-
 tests/mv/update.sh              |    2 +-
 tests/rm/deep-2.sh              |    2 +-
 tests/rm/read-only.sh           |    2 +-
 tests/split/r-chunk.sh          |    2 +-
 tests/tail-2/follow-stdin.sh    |    2 +-
 tests/tail-2/wait.sh            |    2 +-
 tests/touch/no-dereference.sh   |    4 ++--
 13 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/tests/chmod/c-option.sh b/tests/chmod/c-option.sh
index a1782c3..03e1db9 100755
--- a/tests/chmod/c-option.sh
+++ b/tests/chmod/c-option.sh
@@ -31,7 +31,7 @@ chmod u=rwx $file || fail=1
 chmod -c g=rwx $file > out || fail=1
 chmod -c g=rwx $file > empty || fail=1
 
-test -s empty && fail=1
+compare /dev/null empty || fail=1
 case "$(cat out)" in
   "mode of 'f' changed from 0744 "?rwxr--r--?" to 0774 "?rwxrwxr--?) ;;
   *) cat out; fail=1 ;;
diff --git a/tests/cp/cp-a-selinux.sh b/tests/cp/cp-a-selinux.sh
index 3ab7e0e..ca4e8f6 100755
--- a/tests/cp/cp-a-selinux.sh
+++ b/tests/cp/cp-a-selinux.sh
@@ -37,7 +37,8 @@ cp -a c d 2>err || framework_failure_
 cp --preserve=context c e || framework_failure_
 cp --preserve=all c f || framework_failure_
 ls -Z d | grep $ctx || fail=1
-test -s err && fail=1   #there must be no stderr output for -a
+# there must be no stderr output for -a
+compare /dev/null err || fail=1
 ls -Z e | grep $ctx || fail=1
 ls -Z f | grep $ctx || fail=1
 
@@ -116,7 +117,7 @@ echo > g                                     || 
framework_failure_
 # succeed (giving no diagnostics), yet leaving the destination file empty.
 cp -a f g 2>err || fail=1
 test -s g       || fail=1     # The destination file must not be empty.
-test -s err     && fail=1     # There must be no stderr output.
+compare /dev/null err || fail=1
 
 # =====================================================
 # Here, we expect cp to succeed and not warn with "Operation not supported"
diff --git a/tests/cp/cp-mv-enotsup-xattr.sh b/tests/cp/cp-mv-enotsup-xattr.sh
index d711683..6c8fa83 100755
--- a/tests/cp/cp-mv-enotsup-xattr.sh
+++ b/tests/cp/cp-mv-enotsup-xattr.sh
@@ -69,19 +69,19 @@ grep -F "$xattr_pair" out_a >/dev/null \
 # This should pass without diagnostics
 cp -a xattr/a noxattr/ 2>err || fail=1
 test -s noxattr/a   || fail=1  # destination file must not be empty
-test -s err         && fail=1  # there must be no stderr output
+compare /dev/null err || fail=1
 
 rm -f err noxattr/a
 
 # This should pass without diagnostics (new file)
 cp --preserve=all xattr/a noxattr/ 2>err || fail=1
 test -s noxattr/a   || fail=1  # destination file must not be empty
-test -s err         && fail=1  # there must be no stderr output
+compare /dev/null err || fail=1
 
 # This should pass without diagnostics (existing file)
 cp --preserve=all xattr/a noxattr/ 2>err || fail=1
 test -s noxattr/a   || fail=1  # destination file must not be empty
-test -s err         && fail=1  # there must be no stderr output
+compare /dev/null err || fail=1
 
 rm -f err noxattr/a
 
@@ -104,7 +104,7 @@ rm -f err noxattr/a
 # This should pass without diagnostics
 mv xattr/a noxattr/ 2>err || fail=1
 test -s noxattr/a         || fail=1  # destination file must not be empty
-test -s err               && fail=1  # there must be no stderr output
+compare /dev/null err || fail=1
 
 # This should pass and copy xattrs of the symlink
 # since they're not in the 'user.' namespace.
diff --git a/tests/dd/misc.sh b/tests/dd/misc.sh
index bb4748c..f877fdd 100755
--- a/tests/dd/misc.sh
+++ b/tests/dd/misc.sh
@@ -32,12 +32,12 @@ ln -s $tmp_in $tmp_sym || framework_failure_
 
 # check status=none suppresses all output to stderr
 dd status=none if=$tmp_in of=/dev/null 2> err || fail=1
-test -s err && { cat err; fail=1; }
+compare /dev/null err || fail=1
 dd status=none if=$tmp_in skip=2 of=/dev/null 2> err || fail=1
-test -s err && { cat err; fail=1; }
+compare /dev/null err || fail=1
 # check status=none is cumulative with status=noxfer
 dd status=none status=noxfer if=$tmp_in of=/dev/null 2> err || fail=1
-test -s err && { cat err; fail=1; }
+compare /dev/null err || fail=1
 
 dd if=$tmp_in of=$tmp_out 2> /dev/null || fail=1
 compare $tmp_in $tmp_out || fail=1
diff --git a/tests/misc/nice.sh b/tests/misc/nice.sh
index 8efb7d8..d6910c7 100755
--- a/tests/misc/nice.sh
+++ b/tests/misc/nice.sh
@@ -86,7 +86,7 @@ if test x$(nice -n -1 nice 2> /dev/null) = x0 ; then
 else
   # superuser - change succeeds
   nice -n -1 nice 2> err || fail=1
-  test -s err && fail=1
+  compare /dev/null err || fail=1
   test x$(nice -n -1 nice) = x-1 || fail=1
   test x$(nice --1 nice) = x-1 || fail=1
 fi
diff --git a/tests/misc/xattr.sh b/tests/misc/xattr.sh
index 2694246..f208090 100755
--- a/tests/misc/xattr.sh
+++ b/tests/misc/xattr.sh
@@ -66,7 +66,7 @@ getfattr -d c >out_c || skip_ "failed to get xattr of file"
 grep -F "$xattr_pair" out_c || fail=1
 
 # cp's -a option must produce no diagnostics.
-cp -a a d 2>err && test -s err && fail=1
+cp -a a d 2>err && { compare /dev/null err || fail=1; }
 getfattr -d d >out_d || skip_ "failed to get xattr of file"
 grep -F "$xattr_pair" out_d || fail=1
 
diff --git a/tests/mv/update.sh b/tests/mv/update.sh
index 688a8f2..4c0553a 100755
--- a/tests/mv/update.sh
+++ b/tests/mv/update.sh
@@ -30,7 +30,7 @@ for interactive in '' -i; do
     # With coreutils-6.9 and earlier, using --update with -i would
     # mistakenly elicit a prompt.
     $cp_or_mv $interactive --update old new < /dev/null > out 2>&1 || fail=1
-    test -s out && fail=1
+    compare /dev/null out || fail=1
     case "$(cat new)" in new) ;; *) fail=1 ;; esac
     case "$(cat old)" in old) ;; *) fail=1 ;; esac
   done
diff --git a/tests/rm/deep-2.sh b/tests/rm/deep-2.sh
index 24415ed..c3ea085 100755
--- a/tests/rm/deep-2.sh
+++ b/tests/rm/deep-2.sh
@@ -46,7 +46,7 @@ echo n > no || framework_failure_
 rm ---presume-input-tty -r x < no > out || fail=1
 
 # expect empty output
-test -s out && fail=1
+compare /dev/null out || fail=1
 
 # the directory must have been removed
 test -d x && fail=1
diff --git a/tests/rm/read-only.sh b/tests/rm/read-only.sh
index 1ac8f27..377305c 100755
--- a/tests/rm/read-only.sh
+++ b/tests/rm/read-only.sh
@@ -42,7 +42,7 @@ test $skip = 1 \
 # Applying rm -f to a nonexistent file on a read-only file system must succeed.
 rm -f mnt/no-such > out 2>&1 || fail=1
 # It must produce no diagnostic.
-test -s out && fail=1
+compare /dev/null out || fail=1
 
 # However, trying to remove an existing file must fail.
 rm -f mnt/f > out 2>&1 && fail=1
diff --git a/tests/split/r-chunk.sh b/tests/split/r-chunk.sh
index e84dfa5..8a5f221 100755
--- a/tests/split/r-chunk.sh
+++ b/tests/split/r-chunk.sh
@@ -32,7 +32,7 @@ stat x?? 2>/dev/null && fail=1
 printf '1\n2\n3\n4\n5\n' > in || framework_failure_
 
 split -n r/3 in > out || fail=1
-test -s out && fail=1
+compare /dev/null out || fail=1
 
 split -n r/1/3 in > r1 || fail=1
 split -n r/2/3 in > r2 || fail=1
diff --git a/tests/tail-2/follow-stdin.sh b/tests/tail-2/follow-stdin.sh
index 8ca10d6..1769ee2 100755
--- a/tests/tail-2/follow-stdin.sh
+++ b/tests/tail-2/follow-stdin.sh
@@ -28,7 +28,7 @@ timeout 1 tail -f < in > out 2> err
 test $? = 124 || fail=1
 
 # Ensure there was no error output.
-test -s err && fail=1
+compare /dev/null err || fail=1
 
 # Ensure there was
 compare exp out || fail=1
diff --git a/tests/tail-2/wait.sh b/tests/tail-2/wait.sh
index 13898ac..3dec55c 100755
--- a/tests/tail-2/wait.sh
+++ b/tests/tail-2/wait.sh
@@ -51,7 +51,7 @@ for inotify in ---disable-inotify ''; do
 
   grep -Ev 'inotify (resources exhausted|cannot be used)' tail.err > x
   mv x tail.err
-  test -s tail.err && fail=1
+  compare /dev/null tail.err || fail=1
   >tail.err
 
   tail_F()
diff --git a/tests/touch/no-dereference.sh b/tests/touch/no-dereference.sh
index 718fea7..1d012a1 100755
--- a/tests/touch/no-dereference.sh
+++ b/tests/touch/no-dereference.sh
@@ -29,7 +29,7 @@ ln -s file link || framework_failure_
 touch -h no-file 2> err && fail=1
 test -s err || fail=1
 touch -h -c no-file 2> err || fail=1
-test -s err && fail=1
+compare /dev/null err || fail=1
 
 # -h works on regular files
 touch -h file || fail=1
@@ -49,7 +49,7 @@ grep '^#define HAVE_LUTIMES 1' "$CONFIG_HEADER" > /dev/null ||
 touch -h dangling 2> err
 case $? in
   0) test -f nowhere && fail=1
-     test -s err && fail=1;;
+     compare /dev/null err || fail=1;;
   1) grep 'Function not implemented' err \
        && skip_ 'this system lacks the utimensat function'
      fail=1;;
-- 
1.7.7.6