Added/Updated tests\bugs\core_4131_test.py: Enclose query in execute block so that no output will be if it completes successfully.

tests/bugs/core_4131_test.py

@@ -7,6 +7,13 @@ TITLE:       Error when processing an empty data set by window function, if read
 DESCRIPTION:
 JIRA:        CORE-4131
 FBTEST:      bugs.core_4131
+NOTES:
+    3.0.0.30472:
+    cursor identified in the UPDATE or DELETE statement is not positioned on a row. no current record for fetch operation
+
+    [29.07.2023] pzotov
+    Enclose query in execute block so that no output will be if it completes successfully.
+    Previous version of test issued execution plan which had no relation to test purpose and could be changed (thus caused test to be failed).
 """
 
 import pytest
@@ -20,27 +27,26 @@ test_script = """
     insert into test values('qwerty');
     commit;
 
-    set list on;
-    set plan on;
+    set term ^;
+    execute block as
+        declare rn int;
+        declare x type of column test.x;
+    begin
         select row_number() over(order by x) as rn, x
         from test
         where x = 'qwerty'
-    ;
-    -- 3.0.0.30472:
-    -- cursor identified in the UPDATE or DELETE statement is not positioned on a row. no current record for fetch operation
+        into rn, x;
+    end ^
+    set term ;^
+
 """
 
 act = isql_act('db', test_script)
 
-expected_stdout = """
-    PLAN SORT (TEST INDEX (TEST_X))
-    RN                              1
-    X                               qwerty
-"""
+expected_stdout = ""
 
 @pytest.mark.version('>=3.0')
 def test_1(act: Action):
     act.expected_stdout = expected_stdout
-    act.execute()
+    act.execute(combine_output = True)
     assert act.clean_stdout == act.clean_expected_stdout
-