test_cmp: diagnose incorrect arguments

Under normal circumstances, if a test author misspells a filename passed
to test_cmp(), the error is quickly discovered when the test fails
unexpectedly due to test_cmp() being unable to find the file. However,
if the test is expected to fail, as with test_expect_failure(), a
misspelled filename as argument to test_cmp() will go unnoticed since
the test will indeed fail, but for the wrong reason. Make it easier for
test authors to discover such problems early by sanity-checking the
arguments to test_cmp(). To avoid penalizing all clients of test_cmp()
in the general case, only check for missing files if the comparison
fails.

While at it, make test_cmp_bin() sanity-check its arguments, as well.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 3103be8a32393f736481139dd70793ac4e4d97b7..21225330c2f65a95b7356c6ff0468c0a96262719 100644 (file)
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -905,7 +905,13 @@ test_expect_code () {
 # - not all diff versions understand "-u"
 
 test_cmp() {
-       eval "$GIT_TEST_CMP" '"$@"'
+       test $# -eq 2 || BUG "test_cmp requires two arguments"
+       if ! eval "$GIT_TEST_CMP" '"$@"'
+       then
+               test "x$1" = x- || test -e "$1" || BUG "test_cmp '$1' missing"
+               test "x$2" = x- || test -e "$2" || BUG "test_cmp '$2' missing"
+               return 1
+       fi
 }
 
 # Check that the given config key has the expected value.
@@ -934,7 +940,13 @@ test_cmp_config() {
 # test_cmp_bin - helper to compare binary files
 
 test_cmp_bin() {
-       cmp "$@"
+       test $# -eq 2 || BUG "test_cmp_bin requires two arguments"
+       if ! cmp "$@"
+       then
+               test "x$1" = x- || test -e "$1" || BUG "test_cmp_bin '$1' missing"
+               test "x$2" = x- || test -e "$2" || BUG "test_cmp_bin '$2' missing"
+               return 1
+       fi
 }
 
 # Use this instead of test_cmp to compare files that contain expected and