diff --git a/skimage/_shared/_tempfile.py b/skimage/_shared/_tempfile.py new file mode 100644 index 00000000..ea55c11f --- /dev/null +++ b/skimage/_shared/_tempfile.py @@ -0,0 +1,27 @@ +from tempfile import NamedTemporaryFile +from contextlib import contextmanager +import os + +@contextmanager +def temporary_file(suffix=''): + """Yield a writeable temporary filename that is deleted on context exit. + + Parameters + ---------- + suffix : string, optional + The suffix for the file. + + Examples + -------- + >>> import numpy as np + >>> from skimage import io + >>> with temporary_file('.tif') as tempfile: + ... im = np.zeros((5, 5), np.uint8) + ... io.imsave(tempfile, im) + ... assert np.all(io.imread(tempfile) == im) + """ + tempfile_stream = NamedTemporaryFile(suffix=suffix, delete=False) + tempfile = tempfile_stream.name + tempfile_stream.close() + yield tempfile + os.remove(tempfile) diff --git a/skimage/io/tests/test_pil.py b/skimage/io/tests/test_pil.py index fcff1907..0e752da9 100644 --- a/skimage/io/tests/test_pil.py +++ b/skimage/io/tests/test_pil.py @@ -11,6 +11,7 @@ from .. import (imread, imsave, use_plugin, reset_plugins, Image as ioImage) from ..._shared.testing import mono_check, color_check from ..._shared._warnings import expected_warnings +from ..._shared._tempfile import temporary_file from six import BytesIO @@ -99,10 +100,9 @@ def test_imread_truncated_jpg(): def test_jpg_quality_arg(): chessboard = np.load(os.path.join(data_dir, 'chessboard_GRAY_U8.npy')) - with NamedTemporaryFile(suffix='.jpg') as jpg: - fname = jpg.name - imsave(fname, chessboard, quality=95) - im = imread(fname) + with temporary_file(suffix='.jpg') as jpg: + imsave(jpg, chessboard, quality=95) + im = imread(jpg) sim = ssim(chessboard, im, dynamic_range=chessboard.max() - chessboard.min()) assert sim > 0.99 @@ -117,12 +117,10 @@ def test_imread_uint16_big_endian(): class TestSave: def roundtrip_file(self, x): - f = NamedTemporaryFile(suffix='.png') - fname = f.name - f.close() - imsave(fname, x) - y = imread(fname) - return y + with temporary_file(suffix='.png') as fname: + imsave(fname, x) + y = imread(fname) + return y def roundtrip_pil_image(self, x): pil_image = ndarray_to_pil(x) @@ -226,20 +224,18 @@ def test_cmyk(): class TestSaveTIF: def roundtrip(self, dtype, x, compress): - f = NamedTemporaryFile(suffix='.tif') - fname = f.name - f.close() - if dtype == np.bool: - expected = ['low contrast'] - else: - expected = [] - with expected_warnings(expected): - if compress > 0: - imsave(fname, x, compress=compress) + with temporary_file(suffix='.tif') as fname: + if dtype == np.bool: + expected = ['low contrast'] else: - imsave(fname, x) - y = imread(fname) - assert_array_equal(x, y) + expected = [] + with expected_warnings(expected): + if compress > 0: + imsave(fname, x, compress=compress) + else: + imsave(fname, x) + y = imread(fname) + assert_array_equal(x, y) def test_imsave_roundtrip(self): for shape in [(10, 10), (10, 10, 3), (10, 10, 4)]: