%%file dna_analysis.py

"""Code for analyzing DNA sequences"""

from __future__ import division

def get_gc_content(seq):
    """Determine the GC content of a sequence"""
    seq = seq.upper()
    gc_content = 100 * (seq.count('G') + seq.count('C')) / len(seq)
    return gc_content

%%file test_dna.py

from dna_analysis import get_gc_content

def test_get_gc_content_zero():
    assert get_gc_content('ATTATTAAA') == 0
    
def test_get_gc_content_lowercase():
    assert get_gc_content('atgcatgc') == 50
    
def test_get_gc_content_multiline():
    sequence = """atta
gccg
attt
cccg"""
    assert get_gc_content(sequence) == 50

!nosetests