Address review comment and update auto_FitTensor test

Author: ihnorton

nipype/interfaces/mrtrix3/base.py

@@ -11,9 +11,7 @@
 
 
 class Info(PackageInfo):
-    version_cmd = which('mrconvert')
-    if version_cmd:
-        version_cmd = version_cmd + ' --version'
+    version_cmd = 'mrconvert --version'
 
     @staticmethod
     def parse_version(raw_info):
@@ -36,11 +34,7 @@ def looseversion(cls):
 
         If no version found, use LooseVersion('0.0.0')
         """
-        ver = cls.version()
-        if ver is None:
-            return LooseVersion('0.0.0')
-
-        return cls.version())
+        return LooseVersion(cls.version() or '0.0.0')
 
 
 class MRTrix3BaseInputSpec(CommandLineInputSpec):

nipype/interfaces/mrtrix3/tests/test_auto_FitTensor.py

@@ -32,6 +32,11 @@ def test_FitTensor_inputs():
             position=-1,
             usedefault=True,
         ),
+        reg_term=dict(
+            argstr='-regularisation %f',
+            max_ver='0.3.13',
+            usedefault=True,
+        ),
     )
     inputs = FitTensor.input_spec()