Add tests for export including control flow models and quantized models (#2430)

* Add tests for export, including control flow export and quantized model export.

* Skip quantization related test for CUDA backend.

Author: junpeiz

python/tests/cuda_skip.py

@@ -74,4 +74,5 @@
     "TestQuantized.test_small_matrix",
     "TestQuantized.test_throw",
     "TestQuantized.test_vjp_scales_biases",
+    "TestExportImport.test_export_quantized_model",
 }

python/tests/test_export_import.py

@@ -346,6 +346,46 @@ def forward(x):
         expected = forward(input_data)
         self.assertTrue(mx.allclose(expected, out))
 
+    def test_export_control_flow(self):
+
+        def fun(x, y):
+            if y.shape[0] <= 2:
+                return x + y
+            else:
+                return x + 2 * y
+
+        for y in (mx.array([1, 2, 3]), mx.array([1, 2])):
+            for shapeless in (True, False):
+                with self.subTest(y=y, shapeless=shapeless):
+                    x = mx.array(1)
+                    export_path = os.path.join(self.test_dir, "control_flow.mlxfn")
+                    mx.export_function(export_path, fun, x, y, shapeless=shapeless)
+
+                    imported_fn = mx.import_function(export_path)
+                    self.assertTrue(mx.array_equal(imported_fn(x, y)[0], fun(x, y)))
+
+    def test_export_quantized_model(self):
+        for shapeless in (True, False):
+            with self.subTest(shapeless=shapeless):
+                model = nn.Sequential(
+                    nn.Linear(1024, 512), nn.ReLU(), nn.Linear(512, 1024)
+                )
+                model.eval()
+                mx.eval(model.parameters())
+                input_data = mx.ones(shape=(512, 1024))
+                nn.quantize(model)
+                self.assertTrue(isinstance(model.layers[0], nn.QuantizedLinear))
+                self.assertTrue(isinstance(model.layers[2], nn.QuantizedLinear))
+                mx.eval(model.parameters())
+
+                export_path = os.path.join(self.test_dir, "quantized_linear.mlxfn")
+                mx.export_function(export_path, model, input_data, shapeless=shapeless)
+
+                imported_fn = mx.import_function(export_path)
+                self.assertTrue(
+                    mx.array_equal(imported_fn(input_data)[0], model(input_data))
+                )
+
 
 if __name__ == "__main__":
     mlx_tests.MLXTestRunner()