Added/Updated tests\bugs\gh_7698_test.py: Checked on 5.0.0.1155 -- all OK.

tests/bugs/gh_7698_test.py

@@ -0,0 +1,34 @@
+#coding:utf-8
+
+"""
+ID:          issue-7698
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7698
+TITLE:       The legacy plan with window functions is broken
+DESCRIPTION:
+NOTES:
+    Confirmed bug on 5.0.0.1149
+    Checked on 5.0.0.1155 -- all OK.
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = f"""
+    set plan on;
+    set planonly;
+    select count(*) over() from rdb$relations;
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    PLAN (RDB$RELATIONS NATURAL)
+"""
+
+@pytest.mark.version('>=3.0')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute(combine_output = True)
+    assert act.clean_stdout == act.clean_expected_stdout