[PATCH topic experiment] tests: add a test which shows current behaviour of topic while using shelve

[Pulkit Goyal]

# HG changeset patch
# User Pulkit Goyal <7895pulkit at gmail.com>
# Date 1491673306 -19800
#      Sat Apr 08 23:11:46 2017 +0530
# Node ID 5fee792a9e2d0c9a4460393295cb7b1623e5a787
# Parent  dad84c052463e5cf57d8a74655c9ee514e76be7b
tests: add a test which shows current behaviour of topic while using shelve

diff -r dad84c052463 -r 5fee792a9e2d tests/test-topic-shelve.t
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-topic-shelve.t	Sat Apr 08 23:11:46 2017 +0530
@@ -0,0 +1,31 @@
+  $ . "$TESTDIR/testlib/topic_setup.sh"
+
+  $ hg init repo
+  $ cd repo
+  $ cat <<EOF >> .hg/hgrc
+  > [extensions]
+  > shelve=
+  > EOF
+
+  $ touch a
+  $ echo "Hello">>a
+  $ hg add a
+  $ hg topic "shelvetest"
+  $ hg topic
+   * shelvetest
+  $ hg shelve
+  shelved as default
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg topic
+  $ hg stack
+  abort: no active topic to list
+  [255]
+  $ hg topic "unshelvetest"
+  $ hg topic
+   * unshelvetest
+  $ hg unshelve
+  unshelving change 'default'
+  $ hg topic
+  $ hg stack
+  abort: no active topic to list
+  [255]