Win32: symlink: add test for `symlink` attribute

Signed-off-by: Bert Belder <bertbelder@gmail.com>

t/t2040-checkout-symlink-attr.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+test_description='checkout symlinks with `symlink` attribute on Windows
+
+Ensures that Git for Windows creates symlinks of the right type,
+as specified by the `symlink` attribute in `.gitattributes`.'
+
+# Tell MSYS to create native symlinks. Without this flag test-lib's
+# prerequisite detection for SYMLINKS doesn't detect the right thing.
+MSYS=winsymlinks:nativestrict && export MSYS
+
+. ./test-lib.sh
+
+if ! test_have_prereq MINGW,SYMLINKS
+then
+	skip_all='skipping $0: MinGW-only test, which requires symlink support.'
+	test_done
+fi
+
+# Adds a symlink to the index without clobbering the work tree.
+cache_symlink () {
+	sha=$(printf '%s' "$1" | git hash-object --stdin -w) &&
+	git update-index --add --cacheinfo 120000,$sha,"$2"
+}
+
+# MSYS2 is very forgiving, it will resolve symlinks even if the
+# symlink type isn't correct. To make this test meaningful, try
+# them with a native, non-MSYS executable.
+cat_native () {
+	filename=$(cygpath -w "$1") &&
+	cmd.exe /c "type \"$filename\""
+}
+
+test_expect_success 'checkout symlinks with attr' '
+	cache_symlink file1 file-link &&
+	cache_symlink dir dir-link &&
+
+	printf "file-link symlink=file\ndir-link symlink=dir\n" >.gitattributes &&
+	git add .gitattributes &&
+
+	git checkout . &&
+
+	mkdir dir &&
+	echo "contents1" >file1 &&
+	echo "contents2" >dir/file2 &&
+
+	test "$(cat_native file-link)" = "contents1" &&
+	test "$(cat_native dir-link/file2)" = "contents2"
+'
+
+test_done