Added/Updated tests\bugs\gh_7993_test.py: Checked on 6.0.0.249. NB: 5.x is also affected and it looks a regression since 5.0.0.1292

Author: pavel-zotov

tests/bugs/gh_7993_test.py

@@ -0,0 +1,50 @@
+#coding:utf-8
+
+"""
+ID:          issue-7993
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7993
+TITLE:       Unexpected results when using CASE WHEN with RIGHT JOIN
+NOTES:
+    [06.02.2024] pzotov
+    Confirmed bug on 6.0.0.247
+    Checked on 6.0.0.249 -- all OK.
+    NB: 5.x is also affected and it looks a regression since 5.0.0.1292 (date of build: 04-dec-2023)
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    recreate table t0(c0 boolean);
+    recreate table t1(c1 boolean);
+
+    insert into t0 (c0) values (true);
+    insert into t1 (c1) values (false);
+
+    set count on;
+    set list on;
+    select t1.c1 as q1_c1, t0.c0 as q1_c0 from t1 right join t0 on t0.c0; -- false true
+    select t1.c1 as q2_c1, t0.c0 as q2_c0 from t1 right join t0 on t0.c0 where (case t1.c1 when t1.c1 then null else true end); -- null true (unexpected)
+    select (case t1.c1 when t1.c1 then null else true end ) as q3_result from t1 right join t0 on t0.c0; -- null
+"""
+
+act = isql_act('db', test_script, substitutions = [('[ \t]+', ' ')])
+
+expected_stdout = """
+    Q1_C1                           <false>
+    Q1_C0                           <true>
+    Records affected: 1
+
+    Records affected: 0
+    
+    Q3_RESULT                       <null>
+    Records affected: 1
+"""
+
+@pytest.mark.version('>=6.0')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute(combine_output = True)
+    assert act.clean_stdout == act.clean_expected_stdout