diff --git a/validator/tests/test_concurrent_atomic/__init__.py b/validator/tests/test_concurrent_atomic/__init__.py
new file mode 100644
index 0000000000..3928c4e7c4
--- /dev/null
+++ b/validator/tests/test_concurrent_atomic/__init__.py
@@ -0,0 +1,16 @@
+# Copyright 2018 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ------------------------------------------------------------------------------
+
+__all__ = []
diff --git a/validator/tests/test_concurrent_atomic/tests.py b/validator/tests/test_concurrent_atomic/tests.py
new file mode 100755
index 0000000000..3b708bd513
--- /dev/null
+++ b/validator/tests/test_concurrent_atomic/tests.py
@@ -0,0 +1,200 @@
+# Copyright 2018 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ------------------------------------------------------------------------------
+
+import logging
+from threading import RLock
+import unittest
+from unittest.mock import patch
+
+from sawtooth_validator.database.dict_database import DictDatabase
+from sawtooth_validator.concurrent.atomic import ConcurrentMultiMap
+from sawtooth_validator.journal.block_cache import BlockCache
+from sawtooth_validator.journal.block_wrapper import BlockStatus
+from sawtooth_validator.journal.block_wrapper import BlockWrapper
+from sawtooth_validator.journal.block_wrapper import NULL_BLOCK_IDENTIFIER
+from sawtooth_validator.journal.block_store import BlockStore
+from sawtooth_validator.journal.block_validator import BlockValidator
+from sawtooth_validator.journal.block_validator import BlockValidationFailure
+from sawtooth_validator.journal.chain import ChainController
+from sawtooth_validator.journal.chain_commit_state import ChainCommitState
+from sawtooth_validator.journal.chain_commit_state import DuplicateTransaction
+from sawtooth_validator.journal.chain_commit_state import DuplicateBatch
+from sawtooth_validator.journal.chain_commit_state import MissingDependency
+from sawtooth_validator.journal.publisher import BlockPublisher
+from sawtooth_validator.journal.timed_cache import TimedCache
+from sawtooth_validator.journal.event_extractors \
+    import BlockEventExtractor
+from sawtooth_validator.journal.event_extractors \
+    import ReceiptEventExtractor
+from sawtooth_validator.journal.batch_injector import \
+    DefaultBatchInjectorFactory
+from sawtooth_validator.concurrent.atomic import Counter
+from sawtooth_validator.server.events.subscription import EventSubscription
+from sawtooth_validator.server.events.subscription import EventFilterFactory
+
+from sawtooth_validator.protobuf.transaction_pb2 import Transaction
+from sawtooth_validator.protobuf.transaction_pb2 import TransactionHeader
+from sawtooth_validator.protobuf.batch_pb2 import Batch
+from sawtooth_validator.protobuf.block_pb2 import Block
+from sawtooth_validator.protobuf.block_pb2 import BlockHeader
+from sawtooth_validator.protobuf.transaction_receipt_pb2 import \
+    TransactionReceipt
+from sawtooth_validator.protobuf.transaction_receipt_pb2 import StateChange
+from sawtooth_validator.protobuf.transaction_receipt_pb2 import StateChangeList
+from sawtooth_validator.protobuf.events_pb2 import Event
+from sawtooth_validator.protobuf.events_pb2 import EventFilter
+
+from sawtooth_validator.state.settings_view import SettingsViewFactory
+from sawtooth_validator.state.settings_cache import SettingsCache
+
+from test_journal.block_tree_manager import BlockTreeManager
+
+from test_journal.mock import MockChainIdManager
+from test_journal.mock import MockBlockSender
+from test_journal.mock import MockBatchSender
+from test_journal.mock import MockNetwork
+from test_journal.mock import MockStateViewFactory, CreateSetting
+from test_journal.mock import MockTransactionExecutor
+from test_journal.mock import MockPermissionVerifier
+from test_journal.mock import SynchronousExecutor
+from test_journal.mock import MockBatchInjectorFactory
+from test_journal.utils import wait_until
+
+from test_journal import mock_consensus
+
+
+LOGGER = logging.getLogger(__name__)
+
+
+class Test_ConcurrentMultiMap(unittest.TestCase):
+    def setUp(self):
+        self.gossip = MockNetwork()
+        self.txn_executor = MockTransactionExecutor()
+        self.block_sender = MockBlockSender()
+        self.batch_sender = MockBatchSender()
+        self.permission_verifier = MockPermissionVerifier()
+        self.blocks_pending = ConcurrentMultiMap()
+
+    def test_generate_and_publish_block(self):
+        """
+        Test that the Journal will produce blocks and consume those blocks
+        to extend the chain.
+        :return:
+        """
+        # construction and wire the journal to the
+        # gossip layer.
+
+        btm = BlockTreeManager()
+        block_publisher = None
+        chain_controller = None
+        try:
+            block_publisher = BlockPublisher(
+                transaction_executor=self.txn_executor,
+                block_cache=btm.block_cache,
+                state_view_factory=MockStateViewFactory(btm.state_db),
+                settings_cache=SettingsCache(
+                    SettingsViewFactory(
+                        btm.state_view_factory),
+                ),
+                block_sender=self.block_sender,
+                batch_sender=self.batch_sender,
+                squash_handler=None,
+                chain_head=btm.block_store.chain_head,
+                identity_signer=btm.identity_signer,
+                data_dir=None,
+                config_dir=None,
+                permission_verifier=self.permission_verifier,
+                check_publish_block_frequency=0.1,
+                batch_observers=[],
+                batch_injector_factory=DefaultBatchInjectorFactory(
+                    block_store=btm.block_store,
+                    state_view_factory=MockStateViewFactory(btm.state_db),
+                    signer=btm.identity_signer))
+
+            block_validator = BlockValidator(
+                state_view_factory=MockStateViewFactory(btm.state_db),
+                block_cache=btm.block_cache,
+                transaction_executor=self.txn_executor,
+                squash_handler=None,
+                identity_signer=btm.identity_signer,
+                data_dir=None,
+                config_dir=None,
+                permission_verifier=self.permission_verifier)
+
+            chain_controller = ChainController(
+                block_cache=btm.block_cache,
+                block_validator=block_validator,
+                state_view_factory=MockStateViewFactory(btm.state_db),
+                chain_head_lock=block_publisher.chain_head_lock,
+                on_chain_updated=block_publisher.on_chain_updated,
+                chain_id_manager=None,
+                data_dir=None,
+                config_dir=None,
+                chain_observers=[])
+
+            self.gossip.on_batch_received = block_publisher.queue_batch
+            self.gossip.on_block_received = chain_controller.queue_block
+
+            block_publisher.start()
+            chain_controller.start()
+
+            # feed it a batch
+            batch = Batch()
+            block_publisher.queue_batch(batch)
+
+            wait_until(lambda: self.block_sender.new_block is not None, 2)
+            self.assertTrue(self.block_sender.new_block is not None)
+
+            block = BlockWrapper(self.block_sender.new_block)
+            chain_controller.queue_block(block)
+
+            # wait for the chain_head to be updated.
+            block_list = []
+            wait_until(lambda: btm.chain_head.identifier ==
+                       block.identifier, 2)
+            self.assertTrue(btm.chain_head.identifier == block.identifier)
+            self.blocks_pending.set(block.identifier, block_list)
+            self.blocks_pending.append(block.identifier, block_list)
+            self.assertTrue(self.blocks_pending.swap(
+                block.identifier, block_list) != [])
+            self.assertTrue(self.blocks_pending.pop(
+                block.identifier, block_list) == [])
+            self.assertTrue(self.blocks_pending.get(
+                block.identifier, block_list) == [])
+            try:
+                self.blocks_pending.swap(block.identifier, block)
+            except Exception:
+                LOGGER.debug("swap raised an exception")
+            try:
+                self.blocks_pending.set(block.identifier, block)
+            except Exception:
+                LOGGER.debug("set raised an exception")
+        finally:
+            if block_publisher is not None:
+                block_publisher.stop()
+            if chain_controller is not None:
+                chain_controller.stop()
+            if block_validator is not None:
+                block_validator.stop()
+
+
+class Test_Counter(unittest.TestCase):
+    def test_counter(self):
+        self.test_counter = Counter(0)
+        self.test_counter.inc(1)
+        self.assertTrue(self.test_counter.get() == 1)
+        self.test_counter.dec(1)
+        self.assertTrue(self.test_counter.get_and_inc(1) == 0)
+        self.assertTrue(self.test_counter.get_and_dec(1) == 1)