Add tests for io.imshow mpl plugin

skimage/io/tests/test_mpl_imshow.py

@@ -0,0 +1,63 @@
+from __future__ import division
+
+import numpy as np
+from skimage import io
+
+io.use_plugin('matplotlib', 'imshow')
+
+
+# test images. Note that they don't have their full range for their dtype,
+# but we still expect the display range to equal the full dtype range.
+im8 = np.array([[0, 64], [128, 240]], np.uint8)
+im16 = im8.astype(np.uint16) * 256
+imf = im8 / 255
+im_lo = imf / 1000
+im_hi = imf + 10
+
+
+
+def n_subplots(ax_im):
+    """Return the number of subplots in the figure containing an ``AxesImage``.
+
+    Parameters
+    ----------
+    ax_im : matplotlib.pyplot.AxesImage object
+        The input ``AxesImage``.
+
+    Returns
+    -------
+    n : int
+        The number of subplots in the corresponding figure.
+
+    Notes
+    -----
+    This function is intended to check whether a colorbar was drawn, in
+    which case two subplots are expected. For standard imshows, one
+    subplot is expected.
+    """
+    return len(ax_im.get_figure().get_axes())
+
+
+def test_uint8():
+    ax_im = io.imshow(im8)
+    assert ax_im.cmap.name == 'gray'
+    assert ax_im.get_clim() == (0, 255)
+    assert n_subplots(ax_im) == 1
+
+
+def test_uint16():
+    ax_im = io.imshow(im16)
+    assert ax_im.cmap.name == 'gray'
+    assert ax_im.get_clim() == (0, 65535)
+    assert n_subplots(ax_im) == 1
+
+
+def test_float():
+    ax_im = io.imshow(imf)
+    assert ax_im.cmap.name == 'gray'
+    assert ax_im.get_clim() == (0, 1)
+    assert n_subplots(ax_im) == 1
+
+
+if __name__ == '__main__':
+    np.testing.run_module_suite()