Helper function to compare nested structures in tests.

spec/test/features/steps/comparedict.py

@@ -0,0 +1,38 @@
+from functools import singledispatch
+
+
+def assert_same_type(f):
+    def wrapper(a, b):
+        if type(a) != type(b):
+            raise TypeError("Non-matching types")
+        return f(a, b)
+    return wrapper
+
+
+@singledispatch
+@assert_same_type
+def is_subset(model, obj):
+    return model == obj
+
+
+@is_subset.register(dict)
+@assert_same_type
+def _(model, obj):
+    for key, value in model.items():
+        if key not in obj or not is_subset(value, obj[key]):
+            return False
+    return True
+
+
+@is_subset.register(list)
+@assert_same_type
+def _(model, obj):
+    if type(model) != type(obj):
+        raise TypeError("Non-matching types")
+    return is_subset(set(model), set(obj))
+
+
+@is_subset.register(set)
+@assert_same_type
+def _(model, obj):
+    return model <= obj