ENH: allow dtifit to crash for invalid tests

unit_tests/fdt/dtifit/feedsRun

@@ -6,7 +6,7 @@ No noise is added, so we expect (near-)perfect fits
 """
 import sys
 import os
-from subprocess import run
+from subprocess import run, CalledProcessError
 import numpy as np
 from numpy import testing
 import nibabel as nib
@@ -141,16 +141,13 @@ def fit_data(directory):
 
     :yield: tuple with
 
-        - base name of the output files
+        - base name of the output files (CalledProcessError if dtifit crashed)
         - boolean indicating whether the --kurt flag was set
         - boolean indicating whether the --kudtdir flag was set
     """
     for kurtdir in (False, True):
         for main_kurt in (False, True):
             for wls in (False, True):  # in this noise-free data the --wls flag should not matter
-                if wls and kurtdir:
-                    # weighted least square not implemented for kurtdir
-                    continue
                 cmd = [
                     'dtifit',
                     '-k', f'{directory}/ref_data.nii.gz',
@@ -160,6 +157,7 @@ def fit_data(directory):
                     '--sse',
                     '--save_tensor',
                 ]
+
                 base_output = f'{directory}/dti'
                 if wls:
                     cmd += ['--wls']
@@ -171,19 +169,29 @@ def fit_data(directory):
                     cmd += ['--kurtdir']
                     base_output += '_kurtdir'
                 cmd.extend(['-o', base_output])
-                run(cmd, check=True)
-                yield base_output, main_kurt, kurtdir
+                try:
+                    run(cmd, check=True)
+                except CalledProcessError as e:
+                    yield e, main_kurt, kurtdir, wls
+                else:
+                    yield base_output, main_kurt, kurtdir, wls
 
 
 # Loops through multiple ways to generate and fit the data and check the output
 for directory, multi_shell, kurt in gen_data():
-    for base_output, fkurt, fkurtdir in fit_data(directory):
+    for base_output, fkurt, fkurtdir, fwls in fit_data(directory):
         print('testing', base_output)
         if (
-            (kurt == 0 and (multi_shell or not (fkurt or fkurtdir))) or
-            (kurt == 1 and fkurt and not fkurtdir) or
-            (kurt == 2 and fkurtdir)
+                (
+                        (kurt == 0 and (multi_shell or not (fkurt or fkurtdir))) or
+                        (kurt == 1 and fkurt and not fkurtdir) or
+                        (kurt == 2 and fkurtdir)
+                ) and (not (fwls and fkurtdir))
         ):
+            if isinstance(base_output, CalledProcessError):  # dtifit crashed
+                print("dtifit crashed on what should be a valid run. Error message printed above.")
+                raise base_output
+
             def compare(name):
                 ref = nib.load(f'{directory}/ref_{name}.nii.gz').get_fdata()
                 fit = nib.load(f'{base_output}_{name}.nii.gz').get_fdata()
@@ -243,6 +251,9 @@ for directory, multi_shell, kurt in gen_data():
                 assert not os.path.isfile(f'{base_output}_kurt3.nii.gz')
                 assert not os.path.isfile(f'{base_output}_MK.nii.gz')
         else:
+            if isinstance(base_output, CalledProcessError):  # dtifit crashed
+                print("dtifit crashed on an invalid run, which is fine")
+                continue
             if fkurtdir and (not multi_shell or kurt == 1):
                 continue  # unpredictable whether this works or not
             print('This fit should be invalid')