Add tests using mocker to main.py

tests/test_main.py

@@ -0,0 +1,31 @@
+import pytest
+from pytest_mock import MockerFixture
+from torchvision import datasets
+from torch.utils.data import DataLoader
+import torch.nn as nn
+from src import main
+
+def test_data_loading_and_preprocessing(mocker: MockerFixture):
+    """Test the data loading and preprocessing steps."""
+    mock_mnist = mocker.patch.object(datasets, 'MNIST')
+    mock_dataloader = mocker.patch.object(DataLoader, '__init__')
+
+    main.load_and_preprocess_data()
+
+    mock_mnist.assert_called_once_with('.', download=True, train=True, transform=main.transform)
+    mock_dataloader.assert_called_once_with(mock_mnist.return_value, batch_size=64, shuffle=True)
+
+def test_model_definition():
+    """Test the model definition."""
+    model = main.Net()
+
+    assert isinstance(model, main.Net)
+    assert isinstance(model.fc1, nn.Linear)
+    assert model.fc1.in_features == 784
+    assert model.fc1.out_features == 128
+    assert isinstance(model.fc2, nn.Linear)
+    assert model.fc2.in_features == 128
+    assert model.fc2.out_features == 64
+    assert isinstance(model.fc3, nn.Linear)
+    assert model.fc3.in_features == 64
+    assert model.fc3.out_features == 10