Added/Updated tests\bugs\gh_7710_test.py: Checked on intermediate build 5.0.0.1164.

Author: pavel-zotov

tests/bugs/gh_7710_test.py

@@ -0,0 +1,46 @@
+#coding:utf-8
+
+"""
+ID:          issue-7710
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7710
+TITLE:       Expression index - more than one null value cause attempt to store duplicate value error
+DESCRIPTION:
+NOTES:
+    [17.08.2023] pzotov
+    Confirmed problem on 5.0.0.1163.
+    Checked on intermediate build 5.0.0.1164.
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory(charset = 'utf8')
+
+test_script = """
+    set bail on;
+    create table test (
+        field1 char(10) not null
+    );
+    commit;
+
+    insert into test(field1) values ('N');
+    insert into test(field1) values ('N');
+    insert into test(field1) values ('I');
+    commit;
+    create unique index test_i1 on test computed by (iif(field1 = 'I', 'I', null));
+    commit;
+    set heading off;
+    select 'Ok.' from rdb$database;
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    Ok.
+"""
+
+@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