added more asserts to the list

UltiSnips/python.snippets

@@ -41,6 +41,14 @@ snippet af "Assert false"
 self.assertFalse(${1:condition})
 endsnippet
 
+snippet ar "Assert raises"
+self.assertRaises(${1:exception}, ${2:function}, ${3:arguments})
+endsnippet
+
+snippet ai "Assert in"
+self.assertIn(${1:needle}, ${2:haystack})
+endsnippet
+
 snippet nocover "Remove the block from the coverage"
 # pragma: no cover
 endsnippet