def test_closest_psd_matrix_import_error(self, input, mocker):
"""Test import error raising if cvxpy is not installed."""
with pytest.raises(ImportError) as import_error:
mocker.patch.dict(sys.modules, {"cvxpy": None})
output = kern.closest_psd_matrix(input, fix_diagonal=True, feastol=1e-10)
assert "CVXPY is required" in str(import_error.value)
def test_closest_psd_matrix_solve_error(self, input, solver):
"""Test verbose error raising if problem.solve crashes."""
with pytest.raises(Exception) as solve_error:
output = kern.closest_psd_matrix(input,
solver=solver,
fix_diagonal=True,
feastol=1e-10)
assert "CVXPY solver did not converge." in str(solve_error.value)
def test_closest_psd_matrix(self, input, fix_diagonal, expected_output):
"""Test obtaining the closest positive semi-definite matrix using a semi-definite program."""
try:
import cvxpy as cp
output = kern.closest_psd_matrix(input, fix_diagonal=fix_diagonal, feastol=1e-10)
except cp.error.SolverError:
pytest.skip(
"The cvxopt solver seems to not be installed on the system."
"It is the default solver for qml.kernels.closest_psd_matrix"
" and can be installed via `pip install cvxopt`."
)
assert np.allclose(output, expected_output, atol=1e-5)
def test_closest_psd_matrix_small_perturb(self):
"""Test obtaining the closest positive semi-definite matrix using a
semi-definite program with a small perturbation input.
The small perturbation ensures that the solver does not get stuck.
"""
input, fix_diagonal, expected_output = (
np.array([[0, 1.000001], [1, 0]]),
True,
np.array([[1, 1], [1, 1]]),
)
try:
import cvxpy as cp
output = kern.closest_psd_matrix(input, fix_diagonal=fix_diagonal, feastol=1e-10)
except cp.error.SolverError:
pytest.skip(
"The cvxopt solver seems to not be installed on the system."
"It is the default solver for qml.kernels.closest_psd_matrix"
" and can be installed via `pip install cvxopt`."
)
assert np.allclose(output, expected_output, atol=1e-5)