test: test_must_be_empty helper

There are quite a lot places where an output file is expected to be
empty, and we fail the test when it is not.  The output from running
the test script with -i -v can be helped if we showed the unexpected
contents at that point.

We could of course do

    >expected.empty && test_cmp expected.empty actual

but this is commmon enough to be done with a dedicated helper.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0040-parse-options.sh

@@ -50,7 +50,7 @@ EOF
 
 test_expect_success 'test help' '
 	test_must_fail test-parse-options -h > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_i18ncmp expect output
 '
 
@@ -75,7 +75,7 @@ check() {
 	shift &&
 	sed "s/^$what .*/$what $expect/" <expect.template >expect &&
 	test-parse-options $* >output 2>output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 }
 
@@ -86,7 +86,7 @@ check_i18n() {
 	shift &&
 	sed "s/^$what .*/$what $expect/" <expect.template >expect &&
 	test-parse-options $* >output 2>output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_i18ncmp expect output
 }
 
@@ -99,7 +99,7 @@ check_unknown() {
 	esac &&
 	cat expect.err >>expect &&
 	test_must_fail test-parse-options $* >output 2>output.err &&
-	test ! -s output &&
+	test_must_be_empty output &&
 	test_cmp expect output.err
 }
 
@@ -112,7 +112,7 @@ check_unknown_i18n() {
 	esac &&
 	cat expect.err >>expect &&
 	test_must_fail test-parse-options $* >output 2>output.err &&
-	test ! -s output &&
+	test_must_be_empty output &&
 	test_i18ncmp expect output.err
 }
 
@@ -149,7 +149,7 @@ test_expect_success 'short options' '
 	test-parse-options -s123 -b -i 1729 -b -vv -n -F my.file \
 	> output 2> output.err &&
 	test_cmp expect output &&
-	test ! -s output.err
+	test_must_be_empty output.err
 '
 
 cat > expect << EOF
@@ -168,7 +168,7 @@ test_expect_success 'long options' '
 	test-parse-options --boolean --integer 1729 --boolean --string2=321 \
 		--verbose --verbose --no-dry-run --abbrev=10 --file fi.le\
 		--obsolete > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -199,7 +199,7 @@ EOF
 test_expect_success 'intermingled arguments' '
 	test-parse-options a1 --string 123 b1 --boolean -j 13 -- --boolean \
 		> output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -217,13 +217,13 @@ EOF
 
 test_expect_success 'unambiguously abbreviated option' '
 	test-parse-options --int 2 --boolean --no-bo > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
 test_expect_success 'unambiguously abbreviated option with "="' '
 	test-parse-options --int=2 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -246,7 +246,7 @@ EOF
 
 test_expect_success 'non ambiguous option (after two options it abbreviates)' '
 	test-parse-options --st 123 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -256,7 +256,7 @@ EOF
 
 test_expect_success 'detect possible typos' '
 	test_must_fail test-parse-options -boolean > output 2> output.err &&
-	test ! -s output &&
+	test_must_be_empty output &&
 	test_cmp typo.err output.err
 '
 
@@ -266,7 +266,7 @@ EOF
 
 test_expect_success 'detect possible typos' '
 	test_must_fail test-parse-options -ambiguous > output 2> output.err &&
-	test ! -s output &&
+	test_must_be_empty output &&
 	test_cmp typo.err output.err
 '
 
@@ -285,7 +285,7 @@ EOF
 
 test_expect_success 'keep some options as arguments' '
 	test-parse-options --quux > output 2> output.err &&
-        test ! -s output.err &&
+	test_must_be_empty output.err &&
         test_cmp expect output
 '
 
@@ -305,7 +305,7 @@ EOF
 test_expect_success 'OPT_DATE() and OPT_SET_PTR() work' '
 	test-parse-options -t "1970-01-01 00:00:01 +0000" --default-string \
 		foo -q > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -324,7 +324,7 @@ EOF
 
 test_expect_success 'OPT_CALLBACK() and OPT_BIT() work' '
 	test-parse-options --length=four -b -4 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -352,13 +352,13 @@ EOF
 
 test_expect_success 'OPT_BIT() and OPT_SET_INT() work' '
 	test-parse-options --set23 -bbbbb --no-or4 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
 test_expect_success 'OPT_NEGBIT() and OPT_SET_INT() work' '
 	test-parse-options --set23 -bbbbb --neg-or4 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -376,19 +376,19 @@ EOF
 
 test_expect_success 'OPT_BIT() works' '
 	test-parse-options -bb --or4 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
 test_expect_success 'OPT_NEGBIT() works' '
 	test-parse-options -bb --no-neg-or4 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
 test_expect_success 'OPT_COUNTUP() with PARSE_OPT_NODASH works' '
 	test-parse-options + + + + + + > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -406,7 +406,7 @@ EOF
 
 test_expect_success 'OPT_NUMBER_CALLBACK() works' '
 	test-parse-options -12345 > output 2> output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
@@ -424,7 +424,7 @@ EOF
 
 test_expect_success 'negation of OPT_NONEG flags is not ambiguous' '
 	test-parse-options --no-ambig >output 2>output.err &&
-	test ! -s output.err &&
+	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 

t/t3400-rebase.sh

@@ -179,7 +179,7 @@ test_expect_success 'default to @{upstream} when upstream arg is missing' '
 test_expect_success 'rebase -q is quiet' '
 	git checkout -b quiet topic &&
 	git rebase -q master >output.out 2>&1 &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'Rebase a commit that sprinkles CRs in' '

t/t3903-stash.sh

@@ -200,17 +200,17 @@ test_expect_success 'apply -q is quiet' '
 	echo foo > file &&
 	git stash &&
 	git stash apply -q > output.out 2>&1 &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'save -q is quiet' '
 	git stash save --quiet > output.out 2>&1 &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'pop -q is quiet' '
 	git stash pop -q > output.out 2>&1 &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'pop -q --index works and is quiet' '
@@ -219,13 +219,13 @@ test_expect_success 'pop -q --index works and is quiet' '
 	git stash save --quiet &&
 	git stash pop -q --index > output.out 2>&1 &&
 	test foo = "$(git show :file)" &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'drop -q is quiet' '
 	git stash &&
 	git stash drop -q > output.out 2>&1 &&
-	test ! -s output.out
+	test_must_be_empty output.out
 '
 
 test_expect_success 'stash -k' '

t/t5521-pull-options.sh

@@ -15,66 +15,66 @@ test_expect_success 'git pull -q' '
 	mkdir clonedq &&
 	(cd clonedq && git init &&
 	git pull -q "../parent" >out 2>err &&
-	test ! -s err &&
-	test ! -s out)
+	test_must_be_empty err &&
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull -q --rebase' '
 	mkdir clonedqrb &&
 	(cd clonedqrb && git init &&
 	git pull -q --rebase "../parent" >out 2>err &&
-	test ! -s err &&
-	test ! -s out &&
+	test_must_be_empty err &&
+	test_must_be_empty out &&
 	git pull -q --rebase "../parent" >out 2>err &&
-	test ! -s err &&
-	test ! -s out)
+	test_must_be_empty err &&
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull' '
 	mkdir cloned &&
 	(cd cloned && git init &&
 	git pull "../parent" >out 2>err &&
 	test -s err &&
-	test ! -s out)
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull --rebase' '
 	mkdir clonedrb &&
 	(cd clonedrb && git init &&
 	git pull --rebase "../parent" >out 2>err &&
 	test -s err &&
-	test ! -s out)
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull -v' '
 	mkdir clonedv &&
 	(cd clonedv && git init &&
 	git pull -v "../parent" >out 2>err &&
 	test -s err &&
-	test ! -s out)
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull -v --rebase' '
 	mkdir clonedvrb &&
 	(cd clonedvrb && git init &&
 	git pull -v --rebase "../parent" >out 2>err &&
 	test -s err &&
-	test ! -s out)
+	test_must_be_empty out)
 '
 
 test_expect_success 'git pull -v -q' '
 	mkdir clonedvq &&
 	(cd clonedvq && git init &&
 	git pull -v -q "../parent" >out 2>err &&
-	test ! -s out &&
-	test ! -s err)
+	test_must_be_empty out &&
+	test_must_be_empty err)
 '
 
 test_expect_success 'git pull -q -v' '
 	mkdir clonedqv &&
 	(cd clonedqv && git init &&
 	git pull -q -v "../parent" >out 2>err &&
-	test ! -s out &&
+	test_must_be_empty out &&
 	test -s err)
 '
 

t/t5702-clone-options.sh

@@ -22,7 +22,7 @@ test_expect_success 'clone -o' '
 test_expect_success 'redirected clone' '
 
 	git clone "file://$(pwd)/parent" clone-redirected >out 2>err &&
-	test ! -s err
+	test_must_be_empty err
 
 '
 test_expect_success 'redirected clone -v' '

t/t7102-reset.sh

@@ -457,7 +457,7 @@ test_expect_success 'disambiguation (1)' '
 	test_must_fail git diff --quiet -- secondfile &&
 	test -z "$(git diff --cached --name-only)" &&
 	test -f secondfile &&
-	test ! -s secondfile
+	test_must_be_empty secondfile
 
 '
 

t/t7400-submodule-basic.sh

@@ -78,7 +78,7 @@ test_expect_success 'submodule add' '
 	(
 		cd addtest &&
 		git submodule add -q "$submodurl" submod >actual &&
-		test ! -s actual &&
+		test_must_be_empty actual &&
 		echo "gitdir: ../.git/modules/submod" >expect &&
 		test_cmp expect submod/.git &&
 		(
@@ -308,7 +308,7 @@ test_expect_success 'update should work when path is an empty dir' '
 
 	mkdir init &&
 	git submodule update -q >update.out &&
-	test ! -s update.out &&
+	test_must_be_empty update.out &&
 
 	inspect init &&
 	test_cmp expect head-sha1
@@ -696,7 +696,7 @@ test_expect_success 'submodule add --name allows to replace a submodule with ano
 		rm -rf repo &&
 		git rm repo &&
 		git submodule add -q --name repo_new "$submodurl/bare.git" repo >actual &&
-		test ! -s actual &&
+		test_must_be_empty actual &&
 		echo "gitdir: ../.git/modules/submod" >expect &&
 		test_cmp expect submod/.git &&
 		(