tests: use 'test_must_be_empty' instead of 'test_cmp <empty> <out>'

Using 'test_must_be_empty' is shorter and more idiomatic than

  >empty &&
  test_cmp empty out

as it saves the creation of an empty file.  Furthermore, sometimes the
expected empty file doesn't have such a descriptive name like 'empty',
and its creation is far away from the place where it's finally used
for comparison (e.g. in 't7600-merge.sh', where two expected empty
files are created in the 'setup' test, but are used only about 500
lines later).

These cases were found by instrumenting 'test_cmp' to error out the
test script when it's used to compare empty files, and then converted
manually.

Note that even after this patch there still remain a lot of cases
where we use 'test_cmp' to check empty files:

  - Sometimes the expected output is not hard-coded in the test, but
    'test_cmp' is used to ensure that two similar git commands produce
    the same output, and that output happens to be empty, e.g. the
    test 'submodule update --merge  - ignores --merge  for new
    submodules' in 't7406-submodule-update.sh'.

  - Repetitive common tasks, including preparing the expected results
    and running 'test_cmp', are often extracted into a helper
    function, and some of this helper's callsites expect no output.

  - For the same reason as above, the whole 'test_expect_success'
    block is within a helper function, e.g. in 't3070-wildmatch.sh'.

  - Or 'test_cmp' is invoked in a loop, e.g. the test 'cvs update
    (-p)' in 't9400-git-cvsserver-server.sh'.

Signed-off-by: SZEDER Gábor <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: szeder

t/t0001-init.sh

@@ -167,9 +167,8 @@ test_expect_success 'reinit' '
 	) &&
 	test_i18ngrep "Initialized empty" again/out1 &&
 	test_i18ngrep "Reinitialized existing" again/out2 &&
-	>again/empty &&
-	test_i18ncmp again/empty again/err1 &&
-	test_i18ncmp again/empty again/err2
+	test_must_be_empty again/err1 &&
+	test_must_be_empty again/err2
 '
 
 test_expect_success 'init with --template' '

t/t0003-attributes.sh

@@ -208,9 +208,8 @@ test_expect_success 'attribute test: --all option' '
 '
 
 test_expect_success 'attribute test: --cached option' '
-	: >empty &&
 	git check-attr --cached --stdin --all <stdin-all | sort >actual &&
-	test_cmp empty actual &&
+	test_must_be_empty actual &&
 	git add .gitattributes a/.gitattributes a/b/.gitattributes &&
 	git check-attr --cached --stdin --all <stdin-all | sort >actual &&
 	test_cmp specified-all actual

t/t0030-stripspace.sh

@@ -320,22 +320,20 @@ test_expect_success \
 
 test_expect_success \
     'spaces with newline at end should be replaced with empty string' '
-    printf "" >expect &&
-
     echo | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     echo "$sss" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     echo "$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     echo "$sss$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     echo "$sss$sss$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual
+    test_must_be_empty actual
 '
 
 test_expect_success \
@@ -349,19 +347,17 @@ test_expect_success \
 
 test_expect_success \
     'spaces without newline at end should be replaced with empty string' '
-    printf "" >expect &&
-
     printf "" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     printf "$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     printf "$sss$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual &&
+    test_must_be_empty actual &&
 
     printf "$sss$sss$sss$sss" | git stripspace >actual &&
-    test_cmp expect actual
+    test_must_be_empty actual
 '
 
 test_expect_success \

t/t0040-parse-options.sh

@@ -286,11 +286,9 @@ test_expect_success 'OPT_CALLBACK() and OPT_BIT() work' '
 	test_cmp expect output
 '
 
->expect
-
 test_expect_success 'OPT_CALLBACK() and callback errors work' '
 	test_must_fail test-parse-options --no-length >output 2>output.err &&
-	test_i18ncmp expect output &&
+	test_must_be_empty output &&
 	test_must_be_empty output.err
 '
 

t/t0061-run-command.sh

@@ -11,7 +11,6 @@ cat >hello-script <<-EOF
 	#!$SHELL_PATH
 	cat hello-script
 EOF
->empty
 
 test_expect_success 'start_command reports ENOENT' '
 	test-tool run-command start-command-ENOENT ./does-not-exist
@@ -23,7 +22,7 @@ test_expect_success 'run_command can run a command' '
 	test-tool run-command run-command ./hello.sh >actual 2>err &&
 
 	test_cmp hello-script actual &&
-	test_cmp empty err
+	test_must_be_empty err
 '
 
 test_expect_success !MINGW 'run_command can run a script without a #! line' '
@@ -34,7 +33,7 @@ test_expect_success !MINGW 'run_command can run a script without a #! line' '
 	test-tool run-command run-command ./hello >actual 2>err &&
 
 	test_cmp hello-script actual &&
-	test_cmp empty err
+	test_must_be_empty err
 '
 
 test_expect_success 'run_command does not try to execute a directory' '
@@ -47,7 +46,7 @@ test_expect_success 'run_command does not try to execute a directory' '
 	PATH=$PWD/bin1:$PWD/bin2:$PATH \
 		test-tool run-command run-command greet >actual 2>err &&
 	test_cmp bin2/greet actual &&
-	test_cmp empty err
+	test_must_be_empty err
 '
 
 test_expect_success POSIXPERM 'run_command passes over non-executable file' '
@@ -64,7 +63,7 @@ test_expect_success POSIXPERM 'run_command passes over non-executable file' '
 	PATH=$PWD/bin1:$PWD/bin2:$PATH \
 		test-tool run-command run-command greet >actual 2>err &&
 	test_cmp bin2/greet actual &&
-	test_cmp empty err
+	test_must_be_empty err
 '
 
 test_expect_success POSIXPERM 'run_command reports EACCES' '

t/t1300-config.sh

@@ -346,12 +346,9 @@ test_expect_success 'working --list' '
 	git config --list > output &&
 	test_cmp expect output
 '
-cat > expect << EOF
-EOF
-
 test_expect_success '--list without repo produces empty output' '
 	git --git-dir=nonexistent config --list >output &&
-	test_cmp expect output
+	test_must_be_empty output
 '
 
 cat > expect << EOF

t/t1410-reflog.sh

@@ -290,9 +290,8 @@ test_expect_success 'stale dirs do not cause d/f conflicts (reflogs off)' '
 	# same as before, but we only create a reflog for "one" if
 	# it already exists, which it does not
 	git -c core.logallrefupdates=false branch one master &&
-	: >expect &&
 	git log -g --format="%gd %gs" one >actual &&
-	test_cmp expect actual
+	test_must_be_empty actual
 '
 
 # Triggering the bug detected by this test requires a newline to fall

t/t1411-reflog-show.sh

@@ -136,13 +136,12 @@ test_expect_success '--date magic does not override explicit @{0} syntax' '
 	test_cmp expect actual
 '
 
-: >expect
 test_expect_success 'empty reflog file' '
 	git branch empty &&
 	git reflog expire --expire=all refs/heads/empty &&
 
 	git log -g empty >actual &&
-	test_cmp expect actual
+	test_must_be_empty actual
 '
 
 # This guards against the alternative of showing the diffs vs. the

t/t1450-fsck.sh

@@ -16,8 +16,7 @@ test_expect_success setup '
 	git checkout HEAD^0 &&
 	test_commit B fileB two &&
 	git tag -d A B &&
-	git reflog expire --expire=now --all &&
-	>empty
+	git reflog expire --expire=now --all
 '
 
 test_expect_success 'loose objects borrowed from alternate are not missing' '
@@ -29,12 +28,12 @@ test_expect_success 'loose objects borrowed from alternate are not missing' '
 		test_commit C fileC one &&
 		git fsck --no-dangling >../actual 2>&1
 	) &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 test_expect_success 'HEAD is part of refs, valid objects appear valid' '
 	git fsck >actual 2>&1 &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 # Corruption tests follow.  Make sure to remove all traces of the
@@ -346,12 +345,12 @@ test_expect_success 'tag with NUL in header' '
 
 test_expect_success 'cleaned up' '
 	git fsck >actual 2>&1 &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 test_expect_success 'rev-list --verify-objects' '
 	git rev-list --verify-objects --all >/dev/null 2>out &&
-	test_cmp empty out
+	test_must_be_empty out
 '
 
 test_expect_success 'rev-list --verify-objects with bad sha1' '

t/t1600-index.sh

@@ -41,8 +41,7 @@ test_expect_success 'no warning with bogus GIT_INDEX_VERSION and existing index'
 		GIT_INDEX_VERSION=1 &&
 		export GIT_INDEX_VERSION &&
 		git add a 2>actual.err &&
-		>expect.err &&
-		test_i18ncmp expect.err actual.err
+		test_must_be_empty actual.err
 	)
 '