diff --git a/tests/unit/test_plugin_xep_0339.py b/tests/unit/test_plugin_xep_0339.py
new file mode 100644
index 00000000..49b1ea47
--- /dev/null
+++ b/tests/unit/test_plugin_xep_0339.py
@@ -0,0 +1,156 @@
+#!/usr/bin/env python3
+
+# Libervia: an XMPP client
+# Copyright (C) 2009-2023 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+from twisted.words.xish import domish
+
+from sat.plugins.plugin_xep_0339 import NS_JINGLE_RTP_SSMA, XEP_0339
+from sat.tools.xml_tools import parse
+
+
+class TestXEP0339:
+    def test_parse_sdp(self, host):
+        """'ssrc' and 'ssrc-group' attributes in SDP are correctly parsed"""
+        xep_0339 = XEP_0339(host)
+
+        call_data = {}
+        metadata = {}
+        media_type = "video"
+        application_data = {}
+        transport_data = {}
+
+        # SDP: a=ssrc:123 label:stream_label
+        attribute = "ssrc"
+        parts = ["123", "label:stream_label"]
+
+        xep_0339._parse_sdp_a_trigger(
+            attribute,
+            parts,
+            call_data,
+            metadata,
+            media_type,
+            application_data,
+            transport_data,
+        )
+
+        assert application_data == {"ssrc": {123: {"label": "stream_label"}}}
+
+        application_data = {}
+
+        # SDP: a=ssrc-group:FID 123 456
+        attribute = "ssrc-group"
+        parts = ["FID", "123", "456"]
+
+        xep_0339._parse_sdp_a_trigger(
+            attribute,
+            parts,
+            call_data,
+            metadata,
+            media_type,
+            application_data,
+            transport_data,
+        )
+
+        assert application_data == {"ssrc-group": {"FID": [123, 456]}}
+
+    def test_generate_sdp(self, host):
+        """'ssrc' and 'ssrc-group' attributes in SDP are correctly generated"""
+        xep_0339 = XEP_0339(host)
+
+        media_data = {
+            "ssrc": {123: {"label": "stream_label"}},
+            "ssrc-group": {"FID": [123, 456]},
+        }
+        sdp_lines = []
+
+        xep_0339._generate_sdp_content_trigger(
+            {}, True, 1, {}, sdp_lines, {}, "", media_data, "video"
+        )
+
+        assert sdp_lines == ["a=ssrc:123 label:stream_label", "a=ssrc-group:FID 123 456"]
+
+    def test_parse_description(self, host):
+        """'<source>' and '<ssrc-group>' elements are correctly parsed"""
+        xep_0339 = XEP_0339(host)
+
+        media_data = {}
+        raw_xml = """
+        <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
+          <source xmlns='urn:xmpp:jingle:apps:rtp:ssma:0' ssrc='1'>
+            <parameter name='cname' value='some_name'/>
+            <parameter name='msid' value='media'/>
+          </source>
+          <ssrc-group xmlns='urn:xmpp:jingle:apps:rtp:ssma:0' semantics='FEC'>
+            <source ssrc='2'/>
+            <source ssrc='3'/>
+          </ssrc-group>
+        </description>
+        """
+        desc_elt = parse(raw_xml)
+
+        xep_0339._parse_description_trigger(desc_elt, media_data)
+
+        assert media_data == {
+            "msid": "media",
+            "ssrc": {
+                1: {
+                    "cname": "some_name",
+                    "msid": "media",
+                }
+            },
+            "ssrc-group": {"FEC": [2, 3]},
+        }
+
+    def test_generate_description(self, host):
+        """'<source>' and '<ssrc-group>' elements are correctly generated"""
+        xep_0339 = XEP_0339(host)
+
+        media_data = {
+            "ssrc": {
+                1: {
+                    "cname": "some_name",
+                    "msid": "media",
+                }
+            },
+            "ssrc-group": {"FEC": [2, 3]},
+        }
+        session = {}
+        desc_elt = domish.Element((None, "description"))
+
+        xep_0339._build_description_trigger(desc_elt, media_data, session)
+
+        source_elts = list(desc_elt.elements(NS_JINGLE_RTP_SSMA, "source"))
+        assert len(source_elts) == 1
+        source_elt = source_elts[0]
+        assert source_elt["ssrc"] == "1"
+        param_elts = list(source_elt.elements(NS_JINGLE_RTP_SSMA, "parameter"))
+        assert len(param_elts) == 2
+        assert param_elts[0]["name"] == "cname"
+        assert param_elts[0]["value"] == "some_name"
+        assert param_elts[1]["name"] == "msid"
+        assert param_elts[1]["value"] == "media"
+
+        ssrc_group_elts = list(desc_elt.elements(NS_JINGLE_RTP_SSMA, "ssrc-group"))
+        assert len(ssrc_group_elts) == 1
+        ssrc_group_elt = ssrc_group_elts[0]
+        assert ssrc_group_elt["semantics"] == "FEC"
+        ssrc_ids = [
+            int(source_elt["ssrc"])
+            for source_elt in ssrc_group_elt.elements(NS_JINGLE_RTP_SSMA, "source")
+        ]
+        assert ssrc_ids == [2, 3]