#18663: document that assertAlmostEqual also works when the values are equal and add tests.

Doc/library/unittest.rst

@@ -1017,7 +1017,7 @@ Test cases
       like the :func:`round` function) and not *significant digits*.
 
       If *delta* is supplied instead of *places* then the difference
-      between *first* and *second* must be less (or more) than *delta*.
+      between *first* and *second* must be less or equal to (or greater than) *delta*.
 
       Supplying both *delta* and *places* raises a ``TypeError``.
 

Lib/unittest/test/test_assertions.py

@@ -33,6 +33,10 @@ class Test_Assertions(unittest.TestCase):
         self.assertNotAlmostEqual(1.1, 1.0, delta=0.05)
         self.assertNotAlmostEqual(1.0, 1.1, delta=0.05)
 
+        self.assertAlmostEqual(1.0, 1.0, delta=0.5)
+        self.assertRaises(self.failureException, self.assertNotAlmostEqual,
+                          1.0, 1.0, delta=0.5)
+
         self.assertRaises(self.failureException, self.assertAlmostEqual,
                           1.1, 1.0, delta=0.05)
         self.assertRaises(self.failureException, self.assertNotAlmostEqual,