code: def test_fista_regression_simplex():
      rng = np.random.RandomState(0)
      w = project_simplex(rng.rand(10))
      X = rng.randn(1000, 10)
      y = np.dot(X, w)
  
      reg = FistaRegressor(penalty="simplex", max_iter=100, verbose=0)
      reg.fit(X, y)
      y_pred = reg.predict(X)
      error = np.sqrt(np.mean((y - y_pred) ** 2))
      np.testing.assert_almost_equal(error, 0.000, 3)
      assert np.all(reg.coef_ >= -1e-12)
      np.testing.assert_almost_equal(np.sum(reg.coef_), 1.0, 3)
  
imports: import numpy
  import pytest
  from scipy.linalg import svd, diagsvd
  from lightning.classification import FistaClassifier
  from lightning.regression import FistaRegressor
  from lightning.impl.penalty import project_simplex, L1Penalty
label_desc: Use image node_id 14 for calling a global function with example usage: test_fista_regression_simplex() without return types