Fix

Author: pp-mo

lib/iris/aux_factory.py

@@ -121,7 +121,7 @@ def _derive_array(self, *dep_arrays, **other_args):
 
         # The dims of all the given components should be the same and, **presumably**,
         #  the same as the result ??
-        for i_dep, (dep, name) in enumerate(zip(dep_arrays, self.dependencies().keys())):
+        for i_dep, (dep, name) in enumerate(zip(dep_arrays, self.dependencies.keys())):
             if dep.ndim != result.ndim:
                 msg = (
                     f"Dependency #{i_dep}, '{name}' has ndims={dep.ndim}, "

lib/iris/tests/unit/aux_factory/test_AuxCoordFactory.py

@@ -177,6 +177,7 @@ def make_co(name, dims):
             self.y = make_co("y", (1, ny, 1))
             self.z = make_co("z", (1, 1, nz))
 
+        @property
         def dependencies(self):
             return {'x': self.x, "y": self.y, "z": self.z}