tests: allow testing if a path is truly a file or a directory

Add test_path_is_file_not_symlink(), test_path_is_dir_not_symlink()
and test_path_is_symlink(). Case of use for the first one
in test t/t3903-stash.sh to replace "test -f" because that function
explicitly want the file not to be a symlink.
Give more friendly error message.

Signed-off-by: COGONI Guillaume <cogoni.guillaume@gmail.com>
Co-authored-by: BRESSAT Jonathan <git.jonathan.bressat@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3903-stash.sh

@@ -390,7 +390,7 @@ test_expect_success SYMLINKS 'stash file to symlink' '
 	rm file &&
 	ln -s file2 file &&
 	git stash save "file to symlink" &&
-	test -f file &&
+	test_path_is_file_not_symlink file &&
 	test bar = "$(cat file)" &&
 	git stash apply &&
 	case "$(ls -l file)" in *" file -> file2") :;; *) false;; esac
@@ -401,7 +401,7 @@ test_expect_success SYMLINKS 'stash file to symlink (stage rm)' '
 	git rm file &&
 	ln -s file2 file &&
 	git stash save "file to symlink (stage rm)" &&
-	test -f file &&
+	test_path_is_file_not_symlink file &&
 	test bar = "$(cat file)" &&
 	git stash apply &&
 	case "$(ls -l file)" in *" file -> file2") :;; *) false;; esac
@@ -413,7 +413,7 @@ test_expect_success SYMLINKS 'stash file to symlink (full stage)' '
 	ln -s file2 file &&
 	git add file &&
 	git stash save "file to symlink (full stage)" &&
-	test -f file &&
+	test_path_is_file_not_symlink file &&
 	test bar = "$(cat file)" &&
 	git stash apply &&
 	case "$(ls -l file)" in *" file -> file2") :;; *) false;; esac

t/test-lib-functions.sh

@@ -856,6 +856,16 @@ test_path_is_file () {
 	fi
 }
 
+test_path_is_file_not_symlink () {
+	test "$#" -ne 1 && BUG "1 param"
+	test_path_is_file "$1" &&
+	if test -h "$1"
+	then
+		echo "$1 shouldn't be a symbolic link"
+		false
+	fi
+}
+
 test_path_is_dir () {
 	test "$#" -ne 1 && BUG "1 param"
 	if ! test -d "$1"
@@ -865,6 +875,16 @@ test_path_is_dir () {
 	fi
 }
 
+test_path_is_dir_not_symlink () {
+	test "$#" -ne 1 && BUG "1 param"
+	test_path_is_dir "$1" &&
+	if test -h "$1"
+	then
+		echo "$1 shouldn't be a symbolic link"
+		false
+	fi
+}
+
 test_path_exists () {
 	test "$#" -ne 1 && BUG "1 param"
 	if ! test -e "$1"
@@ -874,6 +894,15 @@ test_path_exists () {
 	fi
 }
 
+test_path_is_symlink () {
+	test "$#" -ne 1 && BUG "1 param"
+	if ! test -h "$1"
+	then
+		echo "Symbolic link $1 doesn't exist"
+		false
+	fi
+}
+
 # Check if the directory exists and is empty as expected, barf otherwise.
 test_dir_is_empty () {
 	test "$#" -ne 1 && BUG "1 param"