Learning about attrs

pyproject.toml

@@ -7,6 +7,7 @@ authors = ["Attila Domokos <adomokos@gmail.com>"]
 [tool.poetry.dependencies]
 python = "^3.5"
 mamba = "^0.11.0"
+attrs = "^20.1.0"
 
 [tool.poetry.dev-dependencies]
 pytest = "^5.2"

spec/attrs_spec.py

@@ -0,0 +1,102 @@
+from mamba import description, it
+from attr import attrs, attrib
+import attr
+
+
+@attr.s
+class Empty(object):
+    pass
+
+
+@attr.s
+class Coordinates(object):
+    x = attr.ib()
+    y = attr.ib()
+
+
+@attrs
+class SeriousCoordinates(object):
+    x = attrib()
+    y = attrib()
+
+# Subclassing is bad for you...
+@attr.s
+class A(object):
+    a = attr.ib()
+
+    def get_a(self):
+        return self.a
+
+
+@attr.s
+class B(object):
+    b = attr.ib()
+
+
+@attr.s
+class C(A, B):
+    c = attr.ib()
+
+
+@attr.s
+class SomeClass(object):
+    a_number = attr.ib(default=42)
+    list_of_numbers = attr.ib(factory=list)
+
+    def hard_math(self, another_number):
+        return self.a_number + sum(self.list_of_numbers) * another_number
+
+# asdict can accept a lambda
+@attr.s
+class UserList(object):
+    users = attr.ib()
+
+
+@attr.s
+class User(object):
+    email = attr.ib()
+    password = attr.ib()
+
+
+with description('Attrs') as self:
+    with it("works with Empty objects"):
+        empty1 = Empty()
+        empty2 = Empty()
+        assert empty1 == empty2
+        assert (empty1 is empty2) is False
+
+    with it("works with coordinates"):
+        c1 = Coordinates(x=2, y=1)
+        c2 = Coordinates(x=2, y=1)
+        assert c1 == c2
+        c3 = Coordinates(1, 2)
+        assert (c2 != c3)
+
+    with it("works with SeriousCoordinates"):
+        a = Coordinates(1, 2)
+        b = SeriousCoordinates(1, 2)
+        assert attr.fields(Coordinates) == attr.fields(SeriousCoordinates)
+
+    with it("works with inheritance"):
+        i = C(1, 2, 3)
+        assert i == C(1, 2, 3)
+
+    with it("can have various attributes, even lists"):
+        sc = SomeClass(1, [1, 2, 3])
+        assert sc.hard_math(3) == 19
+        assert sc == SomeClass(1, [1, 2, 3])
+
+    with it("can convert to dictionaries"):
+        d1 = attr.asdict(Coordinates(x=1, y=2))
+        assert [*d1.keys()] == ['x', 'y']
+
+    with it("asdict can accept lambda to filter"):
+        user_list = UserList(
+            [User("jane@doe.invalid", "s33kred"),
+             User("joe@doe.invalid", "p4ssw0rd")]
+        )
+        d1 = attr.asdict(
+            user_list,
+            filter=lambda attr, value: attr.name != "password"
+        )
+        assert len(d1['users']) == 2