def test_n_neg_for_empty_sequence():
assert seq_features.n_neg('') == 0
def test_n_neg_for_single_E_or_D():
"""Perform unit tests on n_neg."""
assert seq_features.n_neg('E') == 1
assert seq_features.n_neg('D') == 1
def test_n_neg_for_lower_case_sequences():
assert seq_features.n_neg('acklwttae') == 1
def test_n_neg_for_longer_sequences():
assert seq_features.n_neg('ACKLWTTAE') == 1
assert seq_features.n_neg('DDDDEEEE') == 8
def test_n_neg_for_invalid_amino_acid():
with pytest.raises(RuntimeError) as excinfo:
seq_features.n_neg('Z')
excinfo.match("Z is not a valid amino acid.")
excinfo.match("Z is not a valid amino acid.")
def test_n_neg_for_empty_sequence():
assert sf.n_neg('') == 0
