diff --git a/tests/test_rtutil.py b/tests/test_rtutil.py
index 042634c270bd5cff11c698b22ebd94a018bb4967..0ca15fe9af646d972c5571275663395d9032adce 100644
--- a/tests/test_rtutil.py
+++ b/tests/test_rtutil.py
@@ -14,6 +14,8 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+import contextlib
+
 import pytest
 
 from . import testutil
@@ -46,6 +48,14 @@ def new_client():
         TICKET_DATA = testutil.RTClient.TICKET_DATA.copy()
     return RTClient()
 
+def new_cache(database=':memory:'):
+    db = rtutil.RTLinkCache.setup(database)
+    if db is None:
+        print("NOTE: did not set up database cache at {}".format(database))
+        return contextlib.nullcontext(db)
+    else:
+        return contextlib.closing(db)
+
 @pytest.mark.parametrize('ticket_id,attachment_id,expected', EXPECTED_URLS)
 def test_url(rt, ticket_id, attachment_id, expected):
     if expected is not None:
@@ -125,3 +135,47 @@ def test_uncommon_server_url_parsing():
     client = testutil.RTClient(url + 'REST/1.0/')
     rt = rtutil.RT(client)
     assert rt.url(1).startswith(url)
+
+def test_shared_cache(new_client):
+    ticket_id, _, expected = EXPECTED_URLS[0]
+    expected = DEFAULT_RT_URL + expected
+    with new_cache() as cachedb:
+        rt1 = rtutil.RT(new_client, cachedb)
+        assert rt1.url(ticket_id) == expected
+        new_client.TICKET_DATA.clear()
+        rt2 = rtutil.RT(new_client, cachedb)
+        assert rt2.url(ticket_id) == expected
+        assert not rt2.exists(ticket_id + 1)
+        assert rt1 is not rt2
+
+def test_no_shared_cache(new_client):
+    with new_cache() as cache1, new_cache() as cache2:
+        rt1 = rtutil.RT(new_client, cache1)
+        rt2 = rtutil.RT(new_client, cache2)
+        assert rt1.exists(1)
+        new_client.TICKET_DATA.clear()
+        assert not rt2.exists(1)
+        assert rt1.exists(1)
+
+def test_read_only_cache(new_client, tmp_path):
+    db_path = tmp_path / 'test.db'
+    ticket_id, _, expected = EXPECTED_URLS[0]
+    expected = DEFAULT_RT_URL + expected
+    with new_cache(db_path) as cache1:
+        rt1 = rtutil.RT(new_client, cache1)
+        assert rt1.url(ticket_id) == expected
+    new_client.TICKET_DATA.clear()
+    db_path.chmod(0o400)
+    with new_cache(db_path) as cache2:
+        rt2 = rtutil.RT(new_client, cache2)
+        assert rt2.url(ticket_id) == expected
+        assert rt2.url(ticket_id + 1) is None
+
+def test_results_not_found_only_in_transient_cache(new_client):
+    with new_cache() as cache:
+        rt1 = rtutil.RT(new_client, cache)
+        rt2 = rtutil.RT(new_client, cache)
+        assert not rt1.exists(9)
+        new_client.TICKET_DATA['9'] = [('99', '(Unnamed)', 'text/plain', '0b')]
+        assert not rt1.exists(9)
+        assert rt2.exists(9)