diff --git a/termstr/tests/termstr_test.py b/termstr/tests/termstr_test.py
index 6fbdaca..9e468cb 100755
--- a/termstr/tests/termstr_test.py
+++ b/termstr/tests/termstr_test.py
@@ -10,6 +10,23 @@ import fill3.terminal as terminal
 import termstr
 
 
+class XtermColorsTests(unittest.TestCase):
+
+    def test_xterm_colors(self):
+        self.assertEqual(len(termstr.XTERM_COLORS), 256)
+        self.assertEqual(termstr.XTERM_COLORS[0], (0, 0, 0))
+        self.assertEqual(termstr.XTERM_COLORS[100], (135, 135, 0))
+        self.assertEqual(termstr.XTERM_COLORS[255], (238, 238, 238))
+
+    def test_closest_color_index(self):
+        self.assertEqual(termstr.closest_color_index(
+            (0, 0, 0), termstr.XTERM_COLORS), 0)
+        self.assertEqual(termstr.closest_color_index(
+            (255, 255, 255), termstr.XTERM_COLORS), 15)
+        self.assertEqual(termstr.closest_color_index(
+            (135, 135, 1), termstr.XTERM_COLORS), 100)
+
+
 class CharStyleTests(unittest.TestCase):
 
     def setUp(self):