diff --git a/test/commands/extended/utils_test.py b/test/commands/extended/utils_test.py
new file mode 100644
index 0000000..3e66130
--- /dev/null
+++ b/test/commands/extended/utils_test.py
@@ -0,0 +1,243 @@
+# coding=utf-8
+from __future__ import absolute_import, division, print_function, \
+    unicode_literals
+
+from unittest import TestCase
+
+from iota.commands.extended.utils import iter_used_addresses
+
+from iota import MockAdapter
+from iota.crypto.types import Seed
+from test import mock
+
+
+class IterUsedAddressesTestCase(TestCase):
+    def setUp(self):
+        super(IterUsedAddressesTestCase, self).setUp()
+
+        self.adapter = MockAdapter()
+        self.seed = Seed(trytes='S' * 81)
+        self.address0 = 'A' * 81
+        self.address1 = 'B' * 81
+        self.address2 = 'C' * 81
+        self.address3 = 'D' * 81
+
+        # To speed up the tests, we will mock the address generator.
+        def address_generator(ag, start, step=1):
+            for addy in [self.address0, self.address1, self.address2,
+                         self.address3][start::step]:
+                yield addy
+        self.mock_address_generator = address_generator
+
+    def seed_unused_address(self):
+        self.adapter.seed_response('findTransactions', {
+            'hashes': [],
+        })
+        self.adapter.seed_response('wereAddressesSpentFrom', {
+            'states': [False],
+        })
+
+    def get_all_used_addresses(self, start=0):
+        return [address for address, _
+                in iter_used_addresses(self.adapter, self.seed, start)]
+
+    def test_fist_address_is_not_used(self):
+        """
+        The very fist address is not used. No address is returned.
+        """
+        # Address 0
+        self.seed_unused_address()
+
+        with mock.patch(
+                'iota.crypto.addresses.AddressGenerator.create_iterator',
+                self.mock_address_generator,
+        ):
+            self.assertEqual([], self.get_all_used_addresses())
+
+        self.assertListEqual(
+            self.adapter.requests,
+            [
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address0],
+                },
+            ]
+        )
+
+    def test_transactions_are_considered_used(self):
+        """
+        An address with a transaction is considered used.
+        """
+        # Address 0
+        self.adapter.seed_response('findTransactions', {
+            'hashes': ['T' * 81],
+        })
+
+        # Address 1
+        self.seed_unused_address()
+
+        with mock.patch(
+                'iota.crypto.addresses.AddressGenerator.create_iterator',
+                self.mock_address_generator,
+        ):
+            self.assertEqual([self.address0], self.get_all_used_addresses())
+
+        self.assertListEqual(
+            self.adapter.requests,
+            [
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address1],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address1],
+                },
+            ]
+        )
+
+    def test_spent_from_is_considered_used(self):
+        """
+        An address that was spent from is considered used.
+        """
+        # Address 0
+        self.adapter.seed_response('findTransactions', {
+            'hashes': [],
+        })
+        self.adapter.seed_response('wereAddressesSpentFrom', {
+            'states': [True],
+        })
+
+        # Address 1
+        self.seed_unused_address()
+
+        with mock.patch(
+                'iota.crypto.addresses.AddressGenerator.create_iterator',
+                self.mock_address_generator,
+        ):
+            self.assertEqual([self.address0], self.get_all_used_addresses())
+
+        self.assertListEqual(
+            self.adapter.requests,
+            [
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address1],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address1],
+                },
+            ]
+        )
+
+    def test_start_parameter_is_given(self):
+        """
+        The correct address is returned if a start parameter is given
+        """
+        # Address 1
+        self.adapter.seed_response('findTransactions', {
+            'hashes': ['T' * 81],
+        })
+
+        # Address 2
+        self.seed_unused_address()
+
+        with mock.patch(
+                'iota.crypto.addresses.AddressGenerator.create_iterator',
+                self.mock_address_generator,
+        ):
+            self.assertEqual([self.address1],
+                             self.get_all_used_addresses(start=1))
+
+        self.assertListEqual(
+            self.adapter.requests,
+            [
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address1],
+                },
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address2],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address2],
+                },
+            ]
+        )
+
+    def test_multiple_addresses_return(self):
+        """
+        A larger test that combines multiple cases and more than one address
+        should be returned.
+        Address 0: Was spent from
+        Address 1: Has a transaction
+        Address 2: Is not used. Should not be returned
+        """
+
+        # Address 0
+        self.adapter.seed_response('findTransactions', {
+            'hashes': [],
+        })
+        self.adapter.seed_response('wereAddressesSpentFrom', {
+            'states': [True],
+        })
+
+        # Address 1
+        self.adapter.seed_response('findTransactions', {
+            'hashes': ['T' * 81],
+        })
+
+        # Address 2
+        self.seed_unused_address()
+
+        with mock.patch(
+                'iota.crypto.addresses.AddressGenerator.create_iterator',
+                self.mock_address_generator,
+        ):
+            self.assertEqual([self.address0, self.address1],
+                             self.get_all_used_addresses())
+
+        self.assertListEqual(
+            self.adapter.requests,
+            [
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address0],
+                },
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address1],
+                },
+                {
+                    'command': 'findTransactions',
+                    'addresses': [self.address2],
+                },
+                {
+                    'command': 'wereAddressesSpentFrom',
+                    'addresses': [self.address2],
+                },
+            ]
+        )