Added/Updated tests\bugs\gh_7924_1_test.py: Checked on 6.0.0.219 after commit bcc53d43

Author: pavel-zotov

tests/bugs/gh_7924_1_test.py

@@ -0,0 +1,66 @@
+#coding:utf-8
+
+"""
+ID:          issue-7924
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7924
+TITLE:       ALTER TABLE ALTER COLUMN <textual_field> can not be changed properly in some cases
+NOTES:
+    [22.01.2024] pzotov
+    Checked on 6.0.0.219 (after commit https://github.com/FirebirdSQL/firebird/commit/bcc53d43c8cd0b904d2963173c153056f9465a09)
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory(charset = 'utf8')
+
+test_script = """
+    alter character set utf8 set default collation unicode_ci;
+    alter character set win1250 set default collation win_cz_ci_ai;
+    alter character set win1252 set default collation win_ptbr;
+    alter character set win1257 set default collation win1257_ee;
+    commit;
+     
+    create table test(
+        f01 varchar(10) character set win1252
+       ,f02 varchar(10) character set win1257
+       ,f03 varchar(10) character set win1251
+    );
+    commit;
+
+     
+    alter table test
+        alter column f01 type varchar(10) character set win1250
+       -----------------------------------------------------------
+       ,alter column f02 type varchar(10) character set win1252
+       -----------------------------------------------------------
+       ,alter column f03 type varchar(10) character set win1257
+    ;
+    commit;
+
+	-- 1. Check that SHOW TABLE will display proper character sets:
+    show table test;
+
+	-- 2. All three statements below raised "Cannot transliterate" before fix:
+	--     Statement failed, SQLSTATE = 22018
+	-- 	   arithmetic exception, numeric overflow, or string truncation
+	--     -Cannot transliterate character between character sets	
+	-- Now all of them must PASS:
+	insert into test(f01) values ('Ł');
+	insert into test(f02) values ('Ð');
+	insert into test(f03) values ('Ģ');
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    F01                             VARCHAR(10) CHARACTER SET WIN1250 COLLATE WIN_CZ_CI_AI Nullable
+    F02                             VARCHAR(10) CHARACTER SET WIN1252 COLLATE WIN_PTBR Nullable
+    F03                             VARCHAR(10) CHARACTER SET WIN1257 COLLATE WIN1257_EE Nullable
+"""
+
+@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