[PATCH 4/6] test-lib-functions: add and use test_cmp_cmd

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Add a "test_cmp_cmd" helper for the common pattern discussed in the
documentation being added here to "t/test-lib-functions.sh".

This implementation leaves the door open for extending this helper
past its obvious limitations, such as:

	test_cmp_cmd "some" "lines" -- <some-cmd>
	test_cmp_cmd --stdin <some-cmd> <expect
	test_cmp_cmd --ignore-stderr "output" <some-cmd>

By using this in t0060-path.sh we'll catch cases where "git" or
"test-tool" errors (such as segfaults or abort()) were previously
hidden, and we'd either pass the test, or fail in some subsequent
assertion.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/t0060-path-utils.sh   | 45 +++++++++++++++++++++++------------------
 t/test-lib-functions.sh | 18 +++++++++++++++++
 2 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 1f2007e62b7..6f278417e83 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -10,8 +10,11 @@ TEST_PASSES_SANITIZE_LEAK=true
 
 norm_path() {
 	expected=$(test-tool path-utils print_path "$2")
-	test_expect_success $3 "normalize path: $1 => $2" \
-	"test \"\$(test-tool path-utils normalize_path_copy '$1')\" = '$expected'"
+	test_expect_success $3 "normalize path: $1 => $2" "
+		echo '$expected' >expect &&
+		test-tool path-utils normalize_path_copy '$1' >actual &&
+		test_cmp expect actual
+	"
 }
 
 relative_path() {
@@ -166,8 +169,10 @@ ancestor D:/Users/me C:/ -1 MINGW
 ancestor //server/share/my-directory //server/share/ 14 MINGW
 
 test_expect_success 'strip_path_suffix' '
-	test c:/msysgit = $(test-tool path-utils strip_path_suffix \
-		c:/msysgit/libexec//git-core libexec/git-core)
+	echo c:/msysgit >expect &&
+	test-tool path-utils strip_path_suffix \
+		c:/msysgit/libexec//git-core libexec/git-core >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success 'absolute path rejects the empty string' '
@@ -189,34 +194,34 @@ test_expect_success 'real path rejects the empty string' '
 
 test_expect_success POSIX 'real path works on absolute paths 1' '
 	nopath="hopefully-absent-path" &&
-	test "/" = "$(test-tool path-utils real_path "/")" &&
-	test "/$nopath" = "$(test-tool path-utils real_path "/$nopath")"
+	test_cmp_cmd / test-tool path-utils real_path "/" &&
+	test_cmp_cmd "/$nopath" test-tool path-utils real_path "/$nopath"
 '
 
 test_expect_success 'real path works on absolute paths 2' '
 	nopath="hopefully-absent-path" &&
 	# Find an existing top-level directory for the remaining tests:
 	d=$(pwd -P | sed -e "s|^\([^/]*/[^/]*\)/.*|\1|") &&
-	test "$d" = "$(test-tool path-utils real_path "$d")" &&
-	test "$d/$nopath" = "$(test-tool path-utils real_path "$d/$nopath")"
+	test_cmp_cmd "$d" test-tool path-utils real_path "$d" &&
+	test_cmp_cmd "$d/$nopath" test-tool path-utils real_path "$d/$nopath"
 '
 
 test_expect_success POSIX 'real path removes extra leading slashes' '
 	nopath="hopefully-absent-path" &&
-	test "/" = "$(test-tool path-utils real_path "///")" &&
-	test "/$nopath" = "$(test-tool path-utils real_path "///$nopath")" &&
+	test_cmp_cmd "/" test-tool path-utils real_path "///" &&
+	test_cmp_cmd "/$nopath" test-tool path-utils real_path "///$nopath" &&
 	# Find an existing top-level directory for the remaining tests:
 	d=$(pwd -P | sed -e "s|^\([^/]*/[^/]*\)/.*|\1|") &&
-	test "$d" = "$(test-tool path-utils real_path "//$d")" &&
-	test "$d/$nopath" = "$(test-tool path-utils real_path "//$d/$nopath")"
+	test_cmp_cmd "$d" test-tool path-utils real_path "//$d" &&
+	test_cmp_cmd "$d/$nopath" test-tool path-utils real_path "//$d/$nopath"
 '
 
 test_expect_success 'real path removes other extra slashes' '
 	nopath="hopefully-absent-path" &&
 	# Find an existing top-level directory for the remaining tests:
 	d=$(pwd -P | sed -e "s|^\([^/]*/[^/]*\)/.*|\1|") &&
-	test "$d" = "$(test-tool path-utils real_path "$d///")" &&
-	test "$d/$nopath" = "$(test-tool path-utils real_path "$d///$nopath")"
+	test_cmp_cmd "$d" test-tool path-utils real_path "$d///" &&
+	test_cmp_cmd "$d/$nopath" test-tool path-utils real_path "$d///$nopath"
 '
 
 test_expect_success SYMLINKS 'real path works on symlinks' '
@@ -227,19 +232,19 @@ test_expect_success SYMLINKS 'real path works on symlinks' '
 	mkdir third &&
 	dir="$(cd .git && pwd -P)" &&
 	dir2=third/../second/other/.git &&
-	test "$dir" = "$(test-tool path-utils real_path $dir2)" &&
+	test_cmp_cmd "$dir" test-tool path-utils real_path $dir2 &&
 	file="$dir"/index &&
-	test "$file" = "$(test-tool path-utils real_path $dir2/index)" &&
+	test_cmp_cmd "$file" test-tool path-utils real_path $dir2/index &&
 	basename=blub &&
-	test "$dir/$basename" = "$(cd .git && test-tool path-utils real_path "$basename")" &&
+	test_cmp_cmd "$dir/$basename" test-tool -C .git path-utils real_path "$basename" &&
 	ln -s ../first/file .git/syml &&
 	sym="$(cd first && pwd -P)"/file &&
-	test "$sym" = "$(test-tool path-utils real_path "$dir2/syml")"
+	test_cmp_cmd "$sym" test-tool path-utils real_path "$dir2/syml"
 '
 
 test_expect_success SYMLINKS 'prefix_path works with absolute paths to work tree symlinks' '
 	ln -s target symlink &&
-	test "$(test-tool path-utils prefix_path prefix "$(pwd)/symlink")" = "symlink"
+	test_cmp_cmd "symlink" test-tool path-utils prefix_path prefix "$(pwd)/symlink"
 '
 
 test_expect_success 'prefix_path works with only absolute path to work tree' '
@@ -255,7 +260,7 @@ test_expect_success 'prefix_path rejects absolute path to dir with same beginnin
 test_expect_success SYMLINKS 'prefix_path works with absolute path to a symlink to work tree having  same beginning as work tree' '
 	git init repo &&
 	ln -s repo repolink &&
-	test "a" = "$(cd repo && test-tool path-utils prefix_path prefix "$(pwd)/../repolink/a")"
+	test_cmp_cmd "a" test-tool -C repo path-utils prefix_path prefix "$(cd repo && pwd)/../repolink/a"
 '
 
 relative_path /foo/a/b/c/	/foo/a/b/	c/
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 6da7273f1d5..63e46442eb6 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1366,6 +1366,24 @@ test_cmp_rev () {
 	fi
 }
 
+# test_cmp_cmd is a convenience helper for doing the more verbose:
+#
+#	echo something >expect &&
+#	<some-command-and-args> >actual &&
+#	test_cmp expect actual
+#
+# As:
+#
+#	test_cmp_cmd something <some-command-and-args>
+test_cmp_cmd () {
+	local expect="$1" &&
+	shift &&
+	printf "%s\n" "$expect" >expect &&
+	"$@" >actual 2>err &&
+	test_must_be_empty err
+	test_cmp expect actual
+}
+
 # Compare paths respecting core.ignoreCase
 test_cmp_fspath () {
 	if test "x$1" = "x$2"
-- 
2.37.1.1095.g64a1e8362fd