diff --git a/tests/bugs/gh_7257_test.py b/tests/bugs/gh_7257_test.py
new file mode 100644
index 00000000..11b110d4
--- /dev/null
+++ b/tests/bugs/gh_7257_test.py
@@ -0,0 +1,138 @@
+#coding:utf-8
+
+"""
+ID:          issue-7257
+ISSUE:       7257
+TITLE:       Support for partial indices
+NOTES:
+    Initial discussion: https://github.com/FirebirdSQL/firebird/issues/3750
+    Checked on 5.0.0.957 (intermediate build).
+    NB. Currently this test contains only trivial cases for check.
+    More complex examples, including misc datatypes (non-ascii, decfloat and int128),
+    will be added later.
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    set bail on;
+    set list on;
+
+    -- test #1: FB must not crash when we create computed-by index which is PARTIAL
+    -- and has the same field that is specified in the computed-by expression.
+    -- https://github.com/FirebirdSQL/firebird/commit/8f12020e254d064f272a64e905ff4c4ed4777c3a
+    recreate table test(
+        id int primary key
+        ,f01 int
+        ,f02 int
+    );
+
+    -- this must pass:
+    create index test_f01 on test computed by (f01)
+    where f01 = 1 --------------------------------- [ ! ]
+    ;
+    commit;
+
+    --#####################################################
+
+    -- test #2: check usage of partial indices:
+    recreate table test(
+        id int primary key
+        ,f01 int
+        ,f02 int
+    );
+    insert into test(id, f01, f02)
+    select i, iif(mod(i,100) < 2, 1, 2), iif(mod(i,150) < 2, 2, 1)
+    from (
+        select row_number()over() as i
+        from rdb$types
+        rows 200
+    );
+    commit;
+    create index test_f01 on test(f01) where f01 = 2;
+    create index test_f02 on test computed by (f02+f01) where f02+f01 = 3;
+
+    set plan on;
+    --set explain on;
+    -- these must use natural scan:
+    select count(*) from test where f01 = 1;
+    select count(*) from test where f02 = 2;
+    -- these must use index:
+    select count(*) from test where f01 = 2;
+    select count(*) from test where f01 + f02 = 3;
+    set plan off;
+    commit;
+
+    --#####################################################
+
+    -- test #3: check descending index when it is PARTIAL.
+    -- See also letter to dimitr, 17.02.2023 21:11.
+    -- https://github.com/FirebirdSQL/firebird/commit/c596b76e40b3c03e712135444d82e20091f9a178
+    recreate table test(
+        id int primary key
+        ,f01 int
+    );
+    insert into test(id, f01)
+    select i, iif( mod(i,20) < 19, null, i*i )
+    from (
+        select row_number()over() as i
+        from rdb$types, rdb$types
+        rows 200
+    );
+    commit;
+     
+    create ascending index test_computed_asc on test (f01) where f01 is null;
+    create descending index test_computed_dec on test (f01) where f01 is null;
+     
+    set plan on;
+     
+    -- test NAVIGATION:
+    select count(*) from (select id from test where f01 is null order by f01 asc ); -- must issue: 190
+    select count(*) from (select id from test where f01 is null order by f01 desc); -- must issue: 190
+     
+    -- test BITMAP:
+    select count(*) from test where f01 is null; -- must issue: 190
+    alter index test_computed_asc inactive;
+     
+    select count(*) from test where f01 is null; -- must issue: 190 - BUT issued 0 before fix.
+    set plan off;
+
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    PLAN (TEST NATURAL)
+    COUNT                           4
+
+    PLAN (TEST NATURAL)
+    COUNT                           3
+
+    PLAN (TEST INDEX (TEST_F01))
+    COUNT                           196
+
+    PLAN (TEST INDEX (TEST_F02))
+    COUNT                           195
+
+
+    PLAN (TEST ORDER TEST_COMPUTED_ASC)
+    COUNT                           190
+
+    PLAN (TEST ORDER TEST_COMPUTED_DEC)
+    COUNT                           190
+
+    PLAN (TEST INDEX (TEST_COMPUTED_ASC))
+    COUNT                           190
+
+    PLAN (TEST INDEX (TEST_COMPUTED_DEC))
+    COUNT                           190
+"""
+
+@pytest.mark.version('>=5.0')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute(combine_output = True)
+    assert act.clean_stdout == act.clean_expected_stdout