New functional test.

tests/functional/cylc-trigger/08-group-trigger.t

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
+# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#-------------------------------------------------------------------------------
+# Test group trigger.
+# See https://github.com/cylc/cylc-flow/issues/6395
+
+. "$(dirname "$0")/test_header"
+
+set_test_number 2
+
+install_workflow "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
+
+run_ok "${TEST_NAME_BASE}-validate" cylc validate "${WORKFLOW_NAME}"
+
+workflow_run_ok "${TEST_NAME_BASE}-run" \
+    cylc play --debug --no-detach --reference-test "${WORKFLOW_NAME}"
+
+purge

tests/functional/cylc-trigger/08-group-trigger/flow.cylc

@@ -0,0 +1,22 @@
+[scheduler]
+    allow implicit tasks = True
+    [[events]]
+        expected task failures = 1/fail
+[scheduling]
+    [[graph]]
+        R1 = """
+            x => a  # spawn a into active pool
+            fail => a => b => c
+            fail => b
+        """
+[runtime]
+    [[fail]]
+        script = """
+            # this should automatically set off-flow prerequisites
+            # 1/x (already satisfied) and 1/fail (not satisfied).
+            # But internal deps "a => b => c" should be respected.
+            cylc trigger ${CYLC_WORKFLOW_ID} //1/a //1/b //1/c
+            false
+        """
+    [[c]]
+        script = "cylc stop $CYLC_WORKFLOW_ID"

tests/functional/cylc-trigger/08-group-trigger/reference.log

@@ -0,0 +1,5 @@
+1/fail -triggered off [] in flow 1
+1/x -triggered off [] in flow 1
+1/a -triggered off ['1/fail', '1/x'] in flow 1
+1/b -triggered off ['1/a', '1/fail'] in flow 1
+1/c -triggered off ['1/b'] in flow 1