Merge pull request #15 from ant-zuev/add_test_core_3858_1

Add a test tests/bugs/core_3858_1_test.py from fbtest.

tests/bugs/core_3858_1_test.py

@@ -0,0 +1,76 @@
+#coding:utf-8
+
+"""
+ID:          issue-4198
+ISSUE:       4198
+TITLE:       Very poor performance of SIMILAR TO on some arguments + unable to disconnect via DELETE FROM MON$ATTACHMENTS
+DESCRIPTION:
+  Confirmed normal work (evaluation for less than 2 ms) on WI-T4.0.0.1598
+  Note. Part of pattern: "[[:ALNUM:]\\_\\-]" -- looks strange but it is correct.
+  And it should NOT be changed to somewhat like "[[:ALNUM:]]\\_\\-": previoud FB versions hanged exactly
+  because of this "strange and wrong" pattern.
+JIRA:        CORE-3858
+FBTEST:      bugs.core_3858
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    set list on;
+    set count on;
+
+    set term ^;
+    execute block as
+    begin
+        rdb$set_context( 'USER_SESSION','DTS_START', cast('now' as timestamp) );
+        rdb$set_context( 'USER_SESSION','MAX_THRESHOLD_MS',  500 );
+        --                                                    ^
+        --                                                    |
+        --                                      #############################
+        --                                      MAX ALLOWED EXECUTION TIME,MS
+        --                                      #############################
+    end
+    ^
+    set term ;^
+
+    select 
+        iif('sdf--asdf_sd.dsfsfh-.sdjskdjfh-_.' 
+        SIMILAR TO 
+        '(([[:ALNUM:]\_\-])+.?)+([[:ALNUM:]\_\-])+' escape '\\', 1, 0) as result from rdb$database
+    --                                                      ^
+    --                                                      |
+    --                  ATTENTION: TWO BACKSLASHES MUST BE HERE WHEN USE FBT_RUN TO CHECK
+    --                             ###############
+    ; 
+
+    set count off;
+    select 
+        iif( evaluated_ms <= max_allowed_ms
+            ,'acceptable'
+            ,'TOO LONG: ' || evaluated_ms || ' ms - this is more then threshold = ' || max_allowed_ms || ' ms'
+           ) as duration
+    from (
+        select 
+             datediff( millisecond from cast(rdb$get_context( 'USER_SESSION','DTS_START') as timestamp) to current_timestamp ) evaluated_ms
+            ,cast( rdb$get_context( 'USER_SESSION','MAX_THRESHOLD_MS' ) as int ) as max_allowed_ms
+        from rdb$database
+    );
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    RESULT                          0
+    Records affected: 1
+    DURATION                        acceptable
+"""
+
+@pytest.mark.version('>=4.0')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute()
+    assert act.clean_stdout == act.clean_expected_stdout
+