diff --git a/tests/test_world_map.py b/tests/test_world_map.py
index aff1108..8a8083c 100644
--- a/tests/test_world_map.py
+++ b/tests/test_world_map.py
@@ -18,7 +18,10 @@
 #    along with PyQSO.  If not, see <http://www.gnu.org/licenses/>.
 
 import unittest
-import os
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 from pyqso.world_map import *
 
 
@@ -38,13 +41,34 @@ class TestMaidenhead(unittest.TestCase):
         assert self.maidenhead.ll2gs(latitude, longitude, subsquare=True) == "IO91gb"
 
     def test_gs2ll(self):
+        """ Check that a Maidenhead grid square can correctly be converted to a latitude-longitude coordinate. """
         gs4 = "JN05"
         assert self.maidenhead.gs2ll(gs4) == (45.5, 1.0)
         gs6 = "JN05aa"
         assert self.maidenhead.gs2ll(gs6) == (45.020833333333336, 0.041666666666666664)
         gs6 = "IO91gb"
-        print(self.maidenhead.gs2ll(gs6))
         assert self.maidenhead.gs2ll(gs6) == (51.0625, -1.4583333333333335)
 
+
+class TestWorldMap(unittest.TestCase):
+
+    """ The unit tests for the WorldMap class. """
+
+    def setUp(self):
+        """ Set up the WorldMap object needed for the unit tests. """
+        PyQSO = mock.MagicMock()
+        self.world_map = WorldMap(application=PyQSO())
+
+    def test_get_worked_grid_squares(self):
+        """ Check that the worked grid squares are determined correctly. """
+        Logbook = mock.MagicMock()
+        Log = mock.MagicMock()
+        logbook = Logbook()
+        l = Log()
+        l.records = [{"CALL": "TEST123", "COUNTRY": "England", "GRIDSQUARE": "IO91gb"}, {"CALL": "TEST456", "COUNTRY": "England", "GRIDSQUARE": "IO90hv"}, {"CALL": "TEST789", "COUNTRY": "England", "GRIDSQUARE": None}]
+        logbook.logs = [l]
+        worked_grid_squares = self.world_map.get_worked_grid_squares(logbook=logbook)
+        assert worked_grid_squares[14, 8]  # IO square.
+
 if(__name__ == '__main__'):
     unittest.main()