Add test cases for quotes in alt texts

tests/sphinx_generic/index.md

@@ -23,7 +23,7 @@ Foo
 
 Bar
 
-![foo](/image.png "Example")
+![foo "handle quotes"](/image.png "Example")
 
     #!/bin/sh
     python

tests/test_basic.py

@@ -226,13 +226,13 @@ class TestParsing(unittest.TestCase):
     def test_image(self):
         self.assertParses(
             """
-            ![foo](/url "title")
+            ![foo "handle quotes"](/url "title")
             """,
             """
             <?xml version="1.0" ?>
             <document source="&lt;string&gt;">
               <paragraph>
-                <image alt="foo" uri="/url"></image>
+                <image alt="foo &quot;handle quotes&quot;" uri="/url"></image>
               </paragraph>
             </document>
             """

tests/test_sphinx.py

@@ -129,7 +129,7 @@ class GenericTests(SphinxIntegrationTests):
     def test_image(self):
         output = self.read_file('index.html')
         self.assertIn(
-            '<p><img alt="foo" src="image.png" /></p>',
+            '<p><img alt="foo &quot;handle quotes&quot;" src="image.png" /></p>',
             output
         )