t6302: for-each-ref tests for ref-filter APIs

Add a test suite for testing the ref-filter APIs used
by for-each-ref. We just intialize the test suite for now.
More tests will be added in the following patches as more
options are added to for-each-ref.

Based-on-patch-by: Jeff King <peff@peff.net>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6302-for-each-ref-filter.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+test_description='test for-each-refs usage of ref-filter APIs'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-gpg.sh
+
+if ! test_have_prereq GPG
+then
+	skip_all="skipping for-each-ref tests, GPG not available"
+	test_done
+fi
+
+test_expect_success 'setup some history and refs' '
+	test_commit one &&
+	test_commit two &&
+	test_commit three &&
+	git checkout -b side &&
+	test_commit four &&
+	git tag -s -m "A signed tag message" signed-tag &&
+	git tag -s -m "Annonated doubly" double-tag signed-tag &&
+	git checkout master &&
+	git update-ref refs/odd/spot master
+'
+
+test_done