removing duplicate dictionaries from a list

attempt.py

import time
import unittest


class DedupTests(unittest.TestCase):

    def setUp(self):
        self.roles = [
            {'extra': '', 'id': 1, 'name': 'role1'},
            {'id': 2, 'name': 'role2', 'extra': ''},
            {'id': 1, 'name': 'role1', 'extra': ''},  # this is a duplicate
            {'extra': '', 'id': 2, 'name': 'role2'}   # this is a duplicate
        ]

        self.expected = [
            {'extra': '', 'id': 1, 'name': 'role1'},
            {'id': 2, 'name': 'role2', 'extra': ''}
        ]
        self.test_start_time = time.time()

    def assertEqualListOfDicts(self, a, b):
        self.assertEqual(len(a), len(b))
        for item in a:
            self.assertIn(item, b)

    def test_dedup_by_containment(self):
        unique_roles = []
        for role in self.roles:
            if role not in unique_roles:
                unique_roles.append(role)
        elapsed = time.time() - self.test_start_time
        print('{} ({}s)'.format(self.id(), elapsed))

        self.assertEqualListOfDicts(unique_roles, self.expected)

    def test_dedup_by_list_comprehension(self):
        unique_roles = [
            dict(t) for t in set([tuple(d.items()) for d in self.roles])
        ]
        elapsed = time.time() - self.test_start_time
        print('{} ({}s)'.format(self.id(), elapsed))

        self.assertEqualListOfDicts(unique_roles, self.expected)

    def test_dedup_by_dict_values(self):
        unique = {}
        for role in self.roles:
            unique[role['id']] = role
        unique_roles = list(unique.values())
        elapsed = time.time() - self.test_start_time
        print('{} ({}s)'.format(self.id(), elapsed))

        self.assertEqualListOfDicts(unique_roles, self.expected)