diff --git a/.travis.yml b/.travis.yml
index 400bd81..78aa402 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,7 +9,7 @@ before_install:
   - sudo apt-get -qq update
 install:
   - sudo apt-get install python-dbus
-  - pip install -U coverage==4.3 pytest pytest-mock
+  - pip install -U coverage==4.3 pytest pytest-mock freezegun
   - pip install codeclimate-test-reporter
   - pip install i3-py Pillow Babel DateTime python-dateutil
   - pip install docker feedparser i3ipc
diff --git a/tests/modules/core/test_datetime.py b/tests/modules/core/test_datetime.py
index b8384d9..33b7d58 100644
--- a/tests/modules/core/test_datetime.py
+++ b/tests/modules/core/test_datetime.py
@@ -1,7 +1,57 @@
 import pytest
+from unittest import mock, TestCase
+from freezegun import freeze_time
+
+import core.config
+import core.input
+import core.widget
+import modules.core.datetime
 
 pytest.importorskip("datetime")
 
-def test_load_module():
-    __import__("modules.core.datetime")
+def build_module(args = []):
+    config = core.config.Config(args)
+    return modules.core.datetime.Module(config=config, theme=None)
+
+def build_widget():
+    return core.widget.Widget()
+
+class DatetimeTest(TestCase):
+    def setup_class(self):
+        locale_patcher = mock.patch('locale.getdefaultlocale')
+        locale_mock = locale_patcher.start()
+        locale_mock.return_value = ('en-US', 'UTF-8')
+
+        self.widget = build_widget()
+
+    def test_load_module(self):
+        __import__("modules.core.datetime")
+
+    @freeze_time('2020-10-15')
+    def test_default_format(self):
+        module = build_module()
+        assert module.full_text(self.widget) == '10/15/2020 12:00:00 AM'
+
+    @freeze_time('2020-10-20')
+    def test_custom_format(self):
+        module = build_module(['-p', 'datetime.format=%Y.%m.%d'])
+        assert module.full_text(self.widget) == '2020.10.20'
+
+    @freeze_time('2020-01-10 10:20:30')
+    @mock.patch('locale.getdefaultlocale')
+    def test_invalid_locale(self, locale_mock):
+        locale_mock.return_value = ('in-IN', 'UTF-0')
+
+        module = build_module()
+        assert module.full_text(self.widget) == '01/10/2020 10:20:30 AM'
+
+    @mock.patch('core.input.register')
+    def test_register_left_mouse_action(self, input_register_mock):
+        module = build_module()
+
+        input_register_mock.assert_called_with(
+            module,
+            button=core.input.LEFT_MOUSE,
+            cmd='calendar'
+        )