Our minimal imageio version cannot read pathlib Paths

[jni]

Description

Discovered on #3961 (comment)

See this build for an example failure: https://travis-ci.org/scikit-image/scikit-image/jobs/545053031#L2708

This causes the test test_masked_registration_padfield_data to fail, since it uses a Path to load the input file.

Way to reproduce

I haven't yet investigated locally.

References

#3331 #3669 both report further issues with pathlib.

[hmaarrfk]

Gotta go to 2.3.0

(skdev) mark2@xps ~/g/scikit-image minimium_imageio|✓                           
$ pip install imageio==2.2.0                                                    
Collecting imageio==2.2.0
  Downloading https://files.pythonhosted.org/packages/a0/4b/f68b2a2e3e98bc006f54ff6fee50f20c7ca4052ec6da68c58c299c7bedf5/imageio-2.2.0.tar.gz (3.3MB)
     |████████████████████████████████| 3.3MB 1.2MB/s 
Requirement already satisfied: numpy in /home/mark2/miniconda3/envs/skdev/lib/python3.7/site-packages (from imageio==2.2.0) (1.16.4)
Requirement already satisfied: pillow in /home/mark2/miniconda3/envs/skdev/lib/python3.7/site-packages (from imageio==2.2.0) (6.0.0)
Building wheels for collected packages: imageio
  Building wheel for imageio (setup.py) ... \^[[/^[[done
  Stored in directory: /home/mark2/.cache/pip/wheels/93/41/b3/e4f5788551792cac4742308f077c32b91753b94b3010d44c5d
Successfully built imageio
Installing collected packages: imageio
  Found existing installation: imageio 2.3.0
    Uninstalling imageio-2.3.0:
      Successfully uninstalled imageio-2.3.0
Successfully installed imageio-2.2.0
(skdev) mark2@xps ~/g/scikit-image minimium_imageio|✓                           
$ pytest ./skimage/feature/tests/test_masked_register_translation.py::test_maske
  d_registration_padfield_data                                                  
============================= test session starts ==============================
platform linux -- Python 3.7.3, pytest-4.6.3, py-1.8.0, pluggy-0.12.0
rootdir: /home/mark2/git/scikit-image/skimage/feature
plugins: forked-1.0.2, xdist-1.29.0, localserver-0.5.0
collected 1 item                                                               

skimage/feature/tests/test_masked_register_translation.py F              [100%]

=================================== FAILURES ===================================
____________________ test_masked_registration_padfield_data ____________________

    def test_masked_registration_padfield_data():
        """ Masked translation registration should behave like in the original
        publication """
        # Test translated from MATLABimplementation `MaskedFFTRegistrationTest`
        # file. You can find the source code here:
        # http://www.dirkpadfield.com/Home/MaskedFFTRegistrationCode.zip
    
        shifts = [(75, 75), (-130, 130), (130, 130)]
        for xi, yi in shifts:
    
            fixed_image = imread(
>               IMAGES_DIR / 'OriginalX{:d}Y{:d}.png'.format(xi, yi))

skimage/feature/tests/test_masked_register_translation.py:95: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
skimage/io/_io.py:48: in imread
    img = call_plugin('imread', fname, plugin=plugin, **plugin_args)
skimage/io/manage_plugins.py:210: in call_plugin
    return func(*args, **kwargs)
skimage/io/_plugins/imageio_plugin.py:10: in imread
    return np.asarray(imageio_imread(*args, **kwargs))
../../miniconda3/envs/skdev/lib/python3.7/site-packages/imageio/core/functions.py:200: in imread
    reader = read(uri, format, 'i', **kwargs)
../../miniconda3/envs/skdev/lib/python3.7/site-packages/imageio/core/functions.py:117: in get_reader
    request = Request(uri, 'r' + mode, **kwargs)
../../miniconda3/envs/skdev/lib/python3.7/site-packages/imageio/core/request.py:120: in __init__
    self._parse_uri(uri)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <imageio.core.request.Request object at 0x7f16420caac8>
uri = PosixPath('/home/mark2/git/scikit-image/skimage/feature/tests/data/OriginalX75Y75.png')

    def _parse_uri(self, uri):
        """ Try to figure our what we were given
        """
        py3k = sys.version_info[0] == 3
        is_read_request = self.mode[0] == 'r'
        is_write_request = self.mode[0] == 'w'
    
        if isinstance(uri, string_types):
            # Explicit
            if uri.startswith('imageio:'):
                if is_write_request:
                    raise RuntimeError('Cannot write to the standard images.')
                fn = uri.split(':', 1)[-1].lower()
                fn, _, zip_part = fn.partition('.zip/')
                if zip_part:
                    fn += '.zip'
                if fn not in EXAMPLE_IMAGES:
                    raise ValueError('Unknown standard image %r.' % fn)
                self._uri_type = URI_FILENAME
                self._filename = get_remote_file('images/' + fn, auto=True)
                if zip_part:
                    self._filename += '/' + zip_part
            elif uri.startswith('http://') or uri.startswith('https://'):
                self._uri_type = URI_HTTP
                self._filename = uri
            elif uri.startswith('ftp://') or uri.startswith('ftps://'):
                self._uri_type = URI_FTP
                self._filename = uri
            elif uri.startswith('file://'):
                self._uri_type = URI_FILENAME
                self._filename = uri[7:]
            elif uri.startswith(SPECIAL_READ_URIS) and is_read_request:
                self._uri_type = URI_BYTES
                self._filename = uri
            elif uri.startswith(RETURN_BYTES) and is_write_request:
                self._uri_type = URI_BYTES
                self._filename = uri
            # Less explicit (particularly on py 2.x)
            elif py3k:
                self._uri_type = URI_FILENAME
                self._filename = uri
            else:  # pragma: no cover - our ref for coverage is py3k
                try:
                    isfile = os.path.isfile(uri)
                except Exception:
                    isfile = False  # If checking does not even work ...
                if isfile:
                    self._uri_type = URI_FILENAME
                    self._filename = uri
                elif len(uri) < 256:  # Can go wrong with veeery tiny images
                    self._uri_type = URI_FILENAME
                    self._filename = uri
                elif isinstance(uri, binary_type) and is_read_request:
                    self._uri_type = URI_BYTES
                    self._filename = '<bytes>'
                    self._bytes = uri
                else:
                    self._uri_type = URI_FILENAME
                    self._filename = uri
        elif py3k and isinstance(uri, binary_type) and is_read_request:
            self._uri_type = URI_BYTES
            self._filename = '<bytes>'
            self._bytes = uri
        # Files
        elif is_read_request:
            if hasattr(uri, 'read') and hasattr(uri, 'close'):
                self._uri_type = URI_FILE
                self._filename = '<file>'
                self._file = uri
        elif is_write_request:
            if hasattr(uri, 'write') and hasattr(uri, 'close'):
                self._uri_type = URI_FILE
                self._filename = '<file>'
                self._file = uri
    
        # Expand user dir
        if self._uri_type == URI_FILENAME and self._filename.startswith('~'):
            self._filename = os.path.expanduser(self._filename)
    
        # Check if a zipfile
        if self._uri_type == URI_FILENAME:
            # Search for zip extension followed by a path separater
            for needle in ['.zip/', '.zip\\']:
                zip_i = self._filename.lower().find(needle)
                if zip_i > 0:
                    zip_i += 4
                    self._uri_type = URI_ZIPPED
                    self._filename_zip = (self._filename[:zip_i],
                                          self._filename[zip_i:].lstrip('/\\'))
                    break
    
        # Check if we could read it
        if self._uri_type is None:
            uri_r = repr(uri)
            if len(uri_r) > 60:
                uri_r = uri_r[:57] + '...'
>           raise IOError("Cannot understand given URI: %s." % uri_r)
E           OSError: Cannot understand given URI: PosixPath('/home/mark2/git/scikit-image/skimage/feature/t....

../../miniconda3/envs/skdev/lib/python3.7/site-packages/imageio/core/request.py:218: OSError
=========================== 1 failed in 0.29 seconds ===========================
(skdev) mark2@xps ~/g/scikit-image minimium_imageio|✓                                                   
$ pip install imageio==2.3.0                                                                            
Collecting imageio==2.3.0
  Using cached https://files.pythonhosted.org/packages/a7/1d/33c8686072148b3b0fcc12a2e0857dd8316b8ae20a0fa66c8d6a6d01c05c/imageio-2.3.0-py2.py3-none-any.whl
Requirement already satisfied: numpy in /home/mark2/miniconda3/envs/skdev/lib/python3.7/site-packages (from imageio==2.3.0) (1.16.4)
Requirement already satisfied: pillow in /home/mark2/miniconda3/envs/skdev/lib/python3.7/site-packages (from imageio==2.3.0) (6.0.0)
Installing collected packages: imageio
  Found existing installation: imageio 2.2.0
    Uninstalling imageio-2.2.0:
      Successfully uninstalled imageio-2.2.0
Successfully installed imageio-2.3.0
(skdev) mark2@xps ~/g/scikit-image minimium_imageio|✓                                                   
$ pytest ./skimage/feature/tests/test_masked_register_translation.py::test_masked_registration_padfield_
  data                                                                                                  
========================================= test session starts ==========================================
platform linux -- Python 3.7.3, pytest-4.6.3, py-1.8.0, pluggy-0.12.0
rootdir: /home/mark2/git/scikit-image/skimage/feature
plugins: forked-1.0.2, xdist-1.29.0, localserver-0.5.0
collected 1 item                                                                                       

skimage/feature/tests/test_masked_register_translation.py .                                      [100%]

======================================= 1 passed in 3.83 seconds =======================================
(skdev) mark2@xps ~/g/scikit-image minimium_imageio|✓