def METHOD_NAME():
    '''Test adding read variables with and without modules. '''
    rwi = ReadWriteInfo()
    sig_b = Signature("b")
    rwi.add_read(sig_b)
    correct = set()
    correct.add(("", sig_b))
    assert rwi.set_of_all_used_vars == correct
    assert rwi.read_list == [("", sig_b)]
    assert rwi.signatures_read == [sig_b]
    # Check that the results are sorted as expected: even though
    # 'a' is added later, it must be first in the output list:
    sig_a = Signature("a")
    rwi.add_read(sig_a)
    correct.add(("", sig_a))
    assert rwi.set_of_all_used_vars == correct
    assert rwi.read_list == [("", sig_a), ("", sig_b)]
    assert rwi.signatures_read == [sig_a, sig_b]
    sig_c = Signature("c")
    rwi.add_read(sig_c, "c_mod")
    correct.add(("c_mod", sig_c))
    assert rwi.set_of_all_used_vars == correct
    assert rwi.read_list == [("", sig_a), ("", sig_b), ("c_mod", sig_c)]
    assert rwi.signatures_read == [sig_a, sig_b, sig_c]
    assert rwi.is_read(sig_a) is True