Added/Updated tests\bugs\gh_7379_test.py: Checked on 5.0.0.938, 4.0.3.2876 -- all fine.

tests/bugs/gh_7379_test.py

@@ -0,0 +1,65 @@
+#coding:utf-8
+
+"""
+ID:          issue-7379
+ISSUE:       7379
+TITLE:       BLOB_APPEND with existing blob accepts malformed string
+NOTES:
+    [16.02.2023] pzotov
+    Confirmed bug on 5.0.0.821, 4.0.3.2873
+    Checked on 5.0.0.938, 4.0.3.2876 -- all fine.
+    ::: NOTE :::
+    If script is executed from command line using ISQL then problem looks as described in the ticket.
+    But if the same script is executed from firebird-qa then FB 5.0.0.821 crashes.
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    set list on;
+
+    set term ^;
+    create table t (b_utf8 blob sub_type text character set utf8)
+    ^
+
+    -- Correct: "Malformed string" error
+    execute block
+    as
+        declare b blob sub_type text character set utf8;
+    begin
+        b = blob_append(b, x'FF');
+    end
+    ^
+
+    -- Wrong: no "Malformed string" error
+    execute block
+    as
+        declare b blob sub_type text character set utf8;
+    begin
+        b = blob_append(b, 'a');
+        -- No error
+        b = blob_append(b, x'FF');
+        -- Malformed blob is saved to table
+        insert into t (b_utf8) values (:b);
+    end
+    ^
+"""
+
+act = isql_act('db', test_script, substitutions=[('-At block line:.*', '')])
+
+expected_stdout = """
+    Statement failed, SQLSTATE = 22000
+    Malformed string
+
+    Statement failed, SQLSTATE = 22000
+    Malformed string
+"""
+
+@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