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#   See COPYING file distributed along with the NiBabel package for the
#   copyright and license terms.
#
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"""Testing mriutils module"""

import pytest
from numpy.testing import assert_almost_equal

from ..mriutils import MRIError, calculate_dwell_time


def test_calculate_dwell_time():
    # Test dwell time calculation
    # This tests only that the calculation does what it appears to; needs some
    # external check
    assert_almost_equal(calculate_dwell_time(3.3, 2, 3), 3.3 / (42.576 * 3.4 * 3 * 3))
    # Echo train length of 1 is valid, but returns 0 dwell time
    assert_almost_equal(calculate_dwell_time(3.3, 1, 3), 0)
    with pytest.raises(MRIError):
        calculate_dwell_time(3.3, 0, 3.0)
    with pytest.raises(MRIError):
        calculate_dwell_time(3.3, 2, -0.1)