def test_DF_mentioned_four_times_in_three_different_documents_is_three(self):
document_collection = [Document("sweden sweden"), Document("sweden"), Document("sweden")]
term = "sweden"
self.assertEquals(document_frequency(document_collection, term), 3)
def test_DF_of_a_term_not_mentioned_in_any_documents_is_zero(self):
document_collection = []
term = "sweden"
self.assertEquals(document_frequency(document_collection, term), 0)
def test_DF_of_a_term_mentioned_in_two_different_documents_is_two(self):
document_collection = [Document("Sweet Norway."), Document("Hei Norway.")]
term = "norway"
self.assertEquals(document_frequency(document_collection, term), 2)
