enh: more thorough testing of LinearParameters base class

Author: oesteban

nitransforms/io/base.py

@@ -31,7 +31,21 @@ def __array__(self):
 
 
 class LinearParameters(StringBasedStruct):
-    """A string-based structure for linear transforms."""
+    """
+    A string-based structure for linear transforms.
+
+    Examples
+    --------
+    >>> lp = LinearParameters()
+    >>> np.all(lp.structarr['parameters'] == np.eye(4))
+    True
+
+    >>> p = np.diag([2., 2., 2., 1.])
+    >>> lp = LinearParameters(p)
+    >>> np.all(lp.structarr['parameters'] == p)
+    True
+
+    """
 
     template_dtype = np.dtype([
         ('parameters', 'f4', (4, 4)),
@@ -59,6 +73,11 @@ def from_fileobj(cls, fileobj, check=True):
         """Read the struct from a file object."""
         return cls.from_string(fileobj.read())
 
+    @classmethod
+    def from_string(cls, string):
+        """Read the struct from string."""
+        raise NotImplementedError
+
 
 def _read_mat(byte_stream):
     mjv, _ = get_matfile_version(byte_stream)
@@ -67,5 +86,7 @@ def _read_mat(byte_stream):
     elif mjv == 1:
         reader = MatFile5Reader(byte_stream)
     elif mjv == 2:
-        raise TransformFileError('Please use HDF reader for matlab v7.3 files')
+        raise TransformFileError('Please use HDF reader for Matlab v7.3 files')
+    else:
+        raise TransformFileError('Not a Matlab file.')
     return reader.get_variables()

nitransforms/tests/test_io.py

@@ -13,7 +13,7 @@
     LinearTransform as LT,
     LinearTransformArray as LTA,
 )
-from ..io.base import _read_mat, TransformFileError
+from ..io.base import _read_mat, LinearParameters, TransformFileError
 
 LPS = np.diag([-1, -1, 1, 1])
 ITK_MAT = LPS.dot(np.ones((4, 4)).dot(LPS))
@@ -145,6 +145,17 @@ def test_ITKLinearTransformArray(tmpdir, data_path):
             xfm2 = itk.ITKLinearTransformArray.from_fileobj(f)
 
 
+def test_LinearParameters(tmpdir):
+    """Just pushes coverage up."""
+    tmpdir.join('file.txt').write('')
+
+    with pytest.raises(NotImplementedError):
+        LinearParameters.from_string('')
+
+    with pytest.raises(NotImplementedError):
+        LinearParameters.from_fileobj(tmpdir.join('file.txt').open())
+
+
 @pytest.mark.parametrize('matlab_ver', ['4', '5'])
 def test_read_mat1(tmpdir, matlab_ver):
     """Test read from matlab."""
@@ -158,16 +169,17 @@ def test_read_mat1(tmpdir, matlab_ver):
     assert np.all(mdict['val'] == np.ones((3,)))
 
 
-def test_read_mat2(tmpdir, monkeypatch):
+@pytest.mark.parametrize('matlab_ver', [-1] + list(range(2, 7)))
+def test_read_mat2(tmpdir, monkeypatch, matlab_ver):
     """Check read matlab raises adequate errors."""
     from ..io import base
 
-    def _mockreturn(arg):
-        return (2, 0)
-
     tmpdir.chdir()
     savemat('val.mat', {'val': np.ones((3,))})
 
+    def _mockreturn(arg):
+        return (matlab_ver, 0)
+
     with monkeypatch.context() as m:
         m.setattr(base, 'get_matfile_version', _mockreturn)
         with pytest.raises(TransformFileError):