diff --git a/tools/run-mypy b/tools/run-mypy
index 692f9c5..423966d 100755
--- a/tools/run-mypy
+++ b/tools/run-mypy
@@ -28,6 +28,8 @@ exclude = [
     # Excluded out of laziness:
     "zulip_bots/zulip_bots/terminal.py",
     "zulip_bots/zulip_bots/simple_lib.py",
+    "zulip_bots/zulip_bots/lib_tests.py",
+    "tools/test-lib",
 ]
 
 parser = argparse.ArgumentParser(description="Run mypy on files tracked by git.")
diff --git a/tools/test-lib b/tools/test-lib
new file mode 100755
index 0000000..8b6bceb
--- /dev/null
+++ b/tools/test-lib
@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+
+import coverage
+import os
+import sys
+import unittest
+
+from importlib import import_module
+
+def run_all():
+    TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))
+    ROOT_DIR = os.path.abspath(os.path.join(TOOLS_DIR, '..'))
+    BOTS_DIR = os.path.join(ROOT_DIR, 'zulib_bots')
+    sys.path.insert(0, BOTS_DIR)
+
+    cov = coverage.Coverage(config_file="tools/.coveragerc")
+    cov.start()
+
+    module = import_module('zulip_bots.lib_tests')
+    suite = unittest.defaultTestLoader.loadTestsFromModule(module)
+
+    suite = unittest.TestSuite([suite])
+    runner = unittest.TextTestRunner(verbosity=2)
+    result = runner.run(suite)
+    if result.failures or result.errors:
+        sys.exit(1)
+
+    cov.stop()
+    cov.data_suffix = False  # Disable suffix so that filename is .coverage
+    cov.save()
+    cov.html_report()
+    print("HTML report saved under directory 'htmlcov'.")
+
+if __name__ == '__main__':
+    run_all()
diff --git a/zulip_bots/zulip_bots/lib_tests.py b/zulip_bots/zulip_bots/lib_tests.py
new file mode 100644
index 0000000..ec674e0
--- /dev/null
+++ b/zulip_bots/zulip_bots/lib_tests.py
@@ -0,0 +1,60 @@
+from unittest import TestCase
+from zulip_bots.lib import (
+    ExternalBotHandler,
+    StateHandler,
+)
+
+class FakeClient:
+    def __init__(self):
+        self.storage = dict()
+
+    def get_profile(self):
+        return dict(
+            user_id='alice',
+            full_name='Alice',
+            email='alice@example.com',
+        )
+
+    def update_storage(self, payload):
+        new_data = payload['storage']
+        self.storage.update(new_data)
+
+        return dict(
+            result='success',
+        )
+
+    def get_storage(self):
+        return dict(
+            result='success',
+            storage=self.storage,
+        )
+
+    def send_message(self, message):
+        pass
+
+class LibTest(TestCase):
+    def test_basics(self):
+        client = FakeClient()
+
+        handler = ExternalBotHandler(
+            client=client,
+            root_dir=None,
+            bot_details=None,
+            bot_config_file=None
+        )
+
+        message = None
+        handler.send_message(message)
+
+    def test_state_handler(self):
+        client = FakeClient()
+
+        state_handler = StateHandler(client)
+        state_handler.put('key', [1, 2, 3])
+        val = state_handler.get('key')
+        self.assertEqual(val, [1, 2, 3])
+
+        # force us to get non-cached values
+        state_handler = StateHandler(client)
+        val = state_handler.get('key')
+        self.assertEqual(val, [1, 2, 3])