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+# tests/rhosocial/activerecord_postgres_test/feature/backend/postgres/test_postgres_hstore_functions.py
+"""
+Tests for PostgreSQL hstore functions.
+
+Functions: hstore_from_record, hstore_from_key_value, hstore_akeys,
+           hstore_skeys, hstore_avals, hstore_svals, hstore_each,
+           hstore_to_array, hstore_to_matrix, hstore_to_json,
+           hstore_to_jsonb, hstore_to_json_loose, hstore_to_jsonb_loose,
+           hstore_slice, hstore_exist, hstore_defined,
+           hstore_delete, hstore_delete_keys, hstore_delete_pairs,
+           hstore_populate_record,
+           hstore_get_value, hstore_get_values, hstore_concat,
+           hstore_key_exists, hstore_all_keys_exist, hstore_any_key_exists,
+           hstore_contains, hstore_contained_by,
+           hstore_subtract_key, hstore_subtract_keys, hstore_subtract_pairs,
+           hstore_to_array_operator, hstore_to_matrix_operator,
+           hstore_record_update,
+           hstore_subscript_get, hstore_subscript_set
+"""
+
+from unittest.mock import MagicMock
+
+from rhosocial.activerecord.backend.impl.postgres.functions.hstore import (
+    _to_sql,
+    hstore_from_record,
+    hstore_from_key_value,
+    hstore_akeys,
+    hstore_skeys,
+    hstore_avals,
+    hstore_svals,
+    hstore_each,
+    hstore_to_array,
+    hstore_to_matrix,
+    hstore_to_json,
+    hstore_to_jsonb,
+    hstore_to_json_loose,
+    hstore_to_jsonb_loose,
+    hstore_slice,
+    hstore_exist,
+    hstore_defined,
+    hstore_delete,
+    hstore_delete_keys,
+    hstore_delete_pairs,
+    hstore_populate_record,
+    hstore_get_value,
+    hstore_get_values,
+    hstore_concat,
+    hstore_key_exists,
+    hstore_all_keys_exist,
+    hstore_any_key_exists,
+    hstore_contains,
+    hstore_contained_by,
+    hstore_subtract_key,
+    hstore_subtract_keys,
+    hstore_subtract_pairs,
+    hstore_to_array_operator,
+    hstore_to_matrix_operator,
+    hstore_record_update,
+    hstore_subscript_get,
+    hstore_subscript_set,
+)
+
+
+class TestToSql:
+    """Tests for the internal _to_sql helper function."""
+
+    def test_to_sql_with_to_sql_method(self):
+        """Test _to_sql with an object that has a to_sql method."""
+        mock_expr = MagicMock()
+        mock_expr.to_sql.return_value = ("mocked_sql",)
+        result = _to_sql(mock_expr)
+        assert result == "mocked_sql"
+        mock_expr.to_sql.assert_called_once()
+
+    def test_to_sql_with_plain_string(self):
+        """Test _to_sql with a plain string value."""
+        result = _to_sql("plain_value")
+        assert result == "plain_value"
+
+    def test_to_sql_with_number(self):
+        """Test _to_sql with a number value."""
+        result = _to_sql(42)
+        assert result == "42"
+
+
+class TestHstoreConstructors:
+    """Tests for hstore constructor functions."""
+
+    def test_hstore_from_record(self):
+        """Test hstore_from_record() function."""
+        result = hstore_from_record("ROW(1,2)")
+        assert result == "hstore(ROW(1,2))"
+
+    def test_hstore_from_key_value(self):
+        """Test hstore_from_key_value() function."""
+        result = hstore_from_key_value("'name'", "'value'")
+        assert result == "hstore('name', 'value')"
+
+
+class TestHstoreKeyValueExtraction:
+    """Tests for hstore key/value extraction functions."""
+
+    def test_hstore_akeys(self):
+        """Test hstore_akeys() function."""
+        result = hstore_akeys("data")
+        assert result == "akeys(data)"
+
+    def test_hstore_skeys(self):
+        """Test hstore_skeys() function."""
+        result = hstore_skeys("data")
+        assert result == "skeys(data)"
+
+    def test_hstore_avals(self):
+        """Test hstore_avals() function."""
+        result = hstore_avals("data")
+        assert result == "avals(data)"
+
+    def test_hstore_svals(self):
+        """Test hstore_svals() function."""
+        result = hstore_svals("data")
+        assert result == "svals(data)"
+
+    def test_hstore_each(self):
+        """Test hstore_each() function."""
+        result = hstore_each("data")
+        assert result == "each(data)"
+
+
+class TestHstoreConversion:
+    """Tests for hstore conversion functions."""
+
+    def test_hstore_to_array(self):
+        """Test hstore_to_array() function."""
+        result = hstore_to_array("data")
+        assert result == "hstore_to_array(data)"
+
+    def test_hstore_to_matrix(self):
+        """Test hstore_to_matrix() function."""
+        result = hstore_to_matrix("data")
+        assert result == "hstore_to_matrix(data)"
+
+    def test_hstore_to_json(self):
+        """Test hstore_to_json() function."""
+        result = hstore_to_json("data")
+        assert result == "hstore_to_json(data)"
+
+    def test_hstore_to_jsonb(self):
+        """Test hstore_to_jsonb() function."""
+        result = hstore_to_jsonb("data")
+        assert result == "hstore_to_jsonb(data)"
+
+    def test_hstore_to_json_loose(self):
+        """Test hstore_to_json_loose() function."""
+        result = hstore_to_json_loose("data")
+        assert result == "hstore_to_json_loose(data)"
+
+    def test_hstore_to_jsonb_loose(self):
+        """Test hstore_to_jsonb_loose() function."""
+        result = hstore_to_jsonb_loose("data")
+        assert result == "hstore_to_jsonb_loose(data)"
+
+
+class TestHstoreSubset:
+    """Tests for hstore subset functions."""
+
+    def test_hstore_slice(self):
+        """Test hstore_slice() function."""
+        result = hstore_slice("data", "ARRAY['a', 'b']")
+        assert result == "slice(data, ARRAY['a', 'b'])"
+
+
+class TestHstoreExistence:
+    """Tests for hstore existence functions."""
+
+    def test_hstore_exist(self):
+        """Test hstore_exist() function."""
+        result = hstore_exist("data", "'name'")
+        assert result == "exist(data, 'name')"
+
+    def test_hstore_defined(self):
+        """Test hstore_defined() function."""
+        result = hstore_defined("data", "'name'")
+        assert result == "defined(data, 'name')"
+
+
+class TestHstoreDelete:
+    """Tests for hstore delete functions."""
+
+    def test_hstore_delete(self):
+        """Test hstore_delete() function."""
+        result = hstore_delete("data", "'name'")
+        assert result == "delete(data, 'name')"
+
+    def test_hstore_delete_keys(self):
+        """Test hstore_delete_keys() function."""
+        result = hstore_delete_keys("data", "ARRAY['name', 'age']")
+        assert result == "delete(data, ARRAY['name', 'age'])"
+
+    def test_hstore_delete_pairs(self):
+        """Test hstore_delete_pairs() function."""
+        result = hstore_delete_pairs("data", "'a=>1'::hstore")
+        assert result == "delete(data, 'a=>1'::hstore)"
+
+
+class TestHstoreRecord:
+    """Tests for hstore record functions."""
+
+    def test_hstore_populate_record(self):
+        """Test hstore_populate_record() function."""
+        result = hstore_populate_record("ROW(1,2)", "'f1=>42'::hstore")
+        assert result == "populate_record(ROW(1,2), 'f1=>42'::hstore)"
+
+
+class TestHstoreOperators:
+    """Tests for hstore operator functions."""
+
+    def test_hstore_get_value(self):
+        """Test hstore_get_value() function (operator ->)."""
+        result = hstore_get_value("data", "'name'")
+        assert result == "data -> 'name'"
+
+    def test_hstore_get_values(self):
+        """Test hstore_get_values() function (operator -> text[])."""
+        result = hstore_get_values("data", "ARRAY['name', 'age']")
+        assert result == "data -> ARRAY['name', 'age']"
+
+    def test_hstore_concat(self):
+        """Test hstore_concat() function (operator ||)."""
+        result = hstore_concat("'a=>1'::hstore", "'b=>2'::hstore")
+        assert result == "'a=>1'::hstore || 'b=>2'::hstore"
+
+    def test_hstore_key_exists(self):
+        """Test hstore_key_exists() function (operator ?)."""
+        result = hstore_key_exists("data", "'name'")
+        assert result == "data ? 'name'"
+
+    def test_hstore_all_keys_exist(self):
+        """Test hstore_all_keys_exist() function (operator ?&)."""
+        result = hstore_all_keys_exist("data", "ARRAY['a', 'b']")
+        assert result == "data ?& ARRAY['a', 'b']"
+
+    def test_hstore_any_key_exists(self):
+        """Test hstore_any_key_exists() function (operator ?|)."""
+        result = hstore_any_key_exists("data", "ARRAY['a', 'b']")
+        assert result == "data ?| ARRAY['a', 'b']"
+
+    def test_hstore_contains(self):
+        """Test hstore_contains() function (operator @>)."""
+        result = hstore_contains("data", "'a=>1'")
+        assert result == "data @> 'a=>1'"
+
+    def test_hstore_contained_by(self):
+        """Test hstore_contained_by() function (operator <@)."""
+        result = hstore_contained_by("'a=>1'", "data")
+        assert result == "'a=>1' <@ data"
+
+
+class TestHstoreSubtraction:
+    """Tests for hstore subtraction operator functions."""
+
+    def test_hstore_subtract_key(self):
+        """Test hstore_subtract_key() function (operator - text)."""
+        result = hstore_subtract_key("data", "'name'")
+        assert result == "data - 'name'"
+
+    def test_hstore_subtract_keys(self):
+        """Test hstore_subtract_keys() function (operator - text[])."""
+        result = hstore_subtract_keys("data", "ARRAY['a', 'b']")
+        assert result == "data - ARRAY['a', 'b']"
+
+    def test_hstore_subtract_pairs(self):
+        """Test hstore_subtract_pairs() function (operator - hstore)."""
+        result = hstore_subtract_pairs("data", "'a=>1'::hstore")
+        assert result == "data - 'a=>1'::hstore"
+
+
+class TestHstoreSpecialOperators:
+    """Tests for hstore special operator functions."""
+
+    def test_hstore_to_array_operator(self):
+        """Test hstore_to_array_operator() function (operator %%)."""
+        result = hstore_to_array_operator("data")
+        assert result == "%%data"
+
+    def test_hstore_to_matrix_operator(self):
+        """Test hstore_to_matrix_operator() function (operator %#)."""
+        result = hstore_to_matrix_operator("data")
+        assert result == "%#data"
+
+    def test_hstore_record_update(self):
+        """Test hstore_record_update() function (operator #=)."""
+        result = hstore_record_update("ROW(1,2)", "'f1=>42'::hstore")
+        assert result == "ROW(1,2) #= 'f1=>42'::hstore"
+
+
+class TestHstoreSubscript:
+    """Tests for hstore subscript access functions."""
+
+    def test_hstore_subscript_get(self):
+        """Test hstore_subscript_get() function."""
+        result = hstore_subscript_get("data", "'name'")
+        assert result == "data['name']"
+
+    def test_hstore_subscript_set(self):
+        """Test hstore_subscript_set() function."""
+        result = hstore_subscript_set("data", "'name'", "'value'")
+        assert result == "data['name'] = 'value'"