[refactor] move tests to tests/, add pytest functions and main() entrypoints

- Moved src/tests/ → tests/
- Added test_* functions with assertions to script-style test files
- Added main() to each so IDEs offer it as a separate run target from pytest
- Fixed cupy_test.py: remove spurious x_gpu += x_cpu, fix duplicate xlabel

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_binary_autoencoder.py

@@ -0,0 +1,86 @@
+import random
+import matplotlib.pyplot as plt
+
+from model.model import Model
+from rbm.entity import Entity, EntityParams, TrainingParams
+from rbm.matrix import Mat, np
+
+N = 8
+N_VIS = N * N
+N_HID = 32
+N_CASES = 400
+
+
+class BinaryAEModel(Model):
+	def __init__(self, name: str, work_dir: str = '.'):
+		super().__init__(name, work_dir)
+		self.unit1 = Entity(
+			(N_VIS, N_HID),
+			EntityParams(),
+			TrainingParams(learning_rate=0.1, momentum=0.9, num_epochs=5000, do_rao_blackwell=True)
+		)
+
+	def forward(self, x: Mat) -> Mat:
+		return self.unit1.forward(x)
+
+	def reconstruct(self, x: Mat) -> Mat:
+		return self.unit1.reconstruct(x)
+
+
+def make_bars_and_stripes(n_cases: int, n: int = N) -> Mat:
+	data = np.zeros((n_cases, n * n), dtype=np.float64)
+	for i in range(n_cases):
+		img = np.zeros((n * n,), dtype=np.float64)
+		if random.random() > 0.5:
+			row = random.randint(0, n - 1)
+			img[row * n:(row + 1) * n] = 1.0
+		else:
+			col = random.randint(0, n - 1)
+			img[col::n] = 1.0
+		data[i] = img
+	return data
+
+
+def test_binary_autoencoder():
+	model = BinaryAEModel("binary_autoencoder_pytest", "results")
+	model.unit1.training_params.num_epochs = 500
+	model.init(0.01)
+	train_batch = make_bars_and_stripes(N_CASES)
+	model.train(train_batch)
+	mae = float(np.mean(np.abs(train_batch - np.array([model.reconstruct(model.forward(x)) for x in train_batch]))))
+	assert mae < 0.4, f"Reconstruction MAE {mae:.4f} too high"
+
+
+def main():
+	model = BinaryAEModel("binary_autoencoder", "results")
+	model.init(0.01)
+
+	train_batch = make_bars_and_stripes(N_CASES)
+	model.train(train_batch)
+	model.save()
+
+	test_batch = make_bars_and_stripes(10)
+	n_show = len(test_batch)
+
+	fig, axes = plt.subplots(2, n_show, figsize=(n_show * 1.5, 3))
+	axes[0, 0].set_ylabel("Original")
+	axes[1, 0].set_ylabel("Recon")
+
+	total_error = 0.0
+	for i, inp in enumerate(test_batch):
+		h = model.forward(inp)
+		recon = model.reconstruct(h)
+		total_error += float(np.mean(np.abs(inp - recon)))
+
+		axes[0, i].imshow(np.asnumpy(np.reshape(inp, (N, N))), cmap='gray', vmin=0, vmax=1)
+		axes[0, i].axis('off')
+		axes[1, i].imshow(np.asnumpy(np.reshape(recon, (N, N))), cmap='gray', vmin=0, vmax=1)
+		axes[1, i].axis('off')
+
+	print(f"Mean reconstruction error: {total_error / n_show:.4f}")
+	plt.tight_layout()
+	plt.show()
+
+
+if __name__ == "__main__":
+	main()