FIX: Add informative error for interfaces that fail to return valid runtime object

nipype/interfaces/base/core.py

@@ -500,6 +500,7 @@ def run(self, cwd=None, ignore_exception=None, **inputs):
             platform=platform.platform(),
             hostname=platform.node(),
             version=self.version)
+        runtime_attrs = set(runtime.dictcopy())
 
         mon_sp = None
         if enable_rm:
@@ -540,6 +541,10 @@ def run(self, cwd=None, ignore_exception=None, **inputs):
             if not ignore_exception:
                 raise
         finally:
+            if runtime is None or runtime_attrs - set(runtime.dictcopy()):
+                raise RuntimeError("{} interface failed to return valid "
+                                   "runtime object".format(
+                                       interface.__class__.__name__))
             # This needs to be done always
             runtime.endTime = dt.isoformat(dt.utcnow())
             timediff = parseutc(runtime.endTime) - parseutc(runtime.startTime)

nipype/interfaces/base/tests/test_core.py

@@ -517,3 +517,29 @@ class OOPBadShell(nib.CommandLine):
     ci = OOPBadShell(command=script_name)
     with pytest.raises(IOError):
         ci.run()
+
+
+def test_runtime_checks():
+    class TestInterface(nib.BaseInterface):
+        class input_spec(nib.TraitedSpec):
+            a = nib.traits.Any()
+        class output_spec(nib.TraitedSpec):
+            b = nib.traits.Any()
+
+        def _run_interface(self, runtime):
+            return runtime
+
+    class NoRuntime(TestInterface):
+        def _run_interface(self, runtime):
+            return None
+
+    class BrokenRuntime(TestInterface):
+        def _run_interface(self, runtime):
+            del runtime.__dict__['cwd']
+            return runtime
+
+    with pytest.raises(RuntimeError):
+        NoRuntime().run()
+
+    with pytest.raises(RuntimeError):
+        BrokenRuntime().run()