test: add some basic cast tests

ibis/backends/tests/test_generic.py

@@ -1758,6 +1758,55 @@ def hash_256(col):
     backend.assert_series_equal(h1, h2)
 
 
+@pytest.mark.parametrize(
+    ("from_val", "from_type", "to_type", "expected"),
+    [
+        param(0, "int", "float", 0.0),
+        param(0.0, "float", "int", 0),
+        param("0", "string", "int", 0),
+        param("0.0", "string", "float", 0.0),
+        param(
+            datetime.datetime(2023, 1, 1),
+            "timestamp",
+            "string",
+            "2023-01-01 00:00:00",
+            marks=[
+                pytest.mark.broken(
+                    ["datafusion"], reason="casts to 1672531200000000 (microseconds)"
+                ),
+                pytest.mark.broken(
+                    ["druid"], reason="casts to 1672531200000 (millisecond)"
+                ),
+                pytest.mark.broken(["mysql"], reason="returns 20230101000000"),
+                pytest.mark.broken(
+                    ["polars"], reason="casts to 1672531200000000000 (nanoseconds)"
+                ),
+            ],
+        ),
+        param(
+            [0, 1, 2],
+            "array<int>",
+            "array<string>",
+            ["0", "1", "2"],
+            marks=[
+                pytest.mark.notyet(["pandas"], reason="casts to ['0']"),
+            ],
+        ),
+        param(
+            {"a": 0, "b": "1"},
+            "struct<a: int, b: string>",
+            "struct<a: string, b: int>",
+            {"a": "0", "b": 1},
+        ),
+    ],
+    ids=str,
+)
+def test_cast(con, from_val, from_type, to_type, expected):
+    expr = ibis.literal(from_val, type=from_type).cast(to_type)
+    result = con.execute(expr)
+    assert result == expected
+
+
 @pytest.mark.notimpl(["pandas", "dask", "oracle", "sqlite"])
 @pytest.mark.parametrize(
     ("from_val", "to_type", "expected"),