Fix #11512. Add an initial test suite for the cgitb, providing 75% coverage.

Patch by Robbie Clemons (robquad), produced at the PyCon 2011 sprints.

Lib/test/test_cgitb.py

+from test.support import run_unittest
+import unittest
+import sys
+import subprocess
+import cgitb
+
+class TestCgitb(unittest.TestCase):
+    
+    def test_fonts(self):
+        text = "Hello Robbie!"
+        self.assertEqual(cgitb.small(text), "<small>{}</small>".format(text))
+        self.assertEqual(cgitb.strong(text), "<strong>{}</strong>".format(text))
+        self.assertEqual(cgitb.grey(text),
+                         '<font color="#909090">{}</font>'.format(text))
+    
+    def test_blanks(self):
+        self.assertEqual(cgitb.small(""), "")
+        self.assertEqual(cgitb.strong(""), "")
+        self.assertEqual(cgitb.grey(""), "")
+                
+    def test_html(self):
+        try:
+            raise ValueError("Hello World")
+        except ValueError as err:
+            # If the html was templated we could do a bit more here.
+            # At least check that we get details on what we just raised.
+            html = cgitb.html(sys.exc_info())
+            self.assertIn("ValueError", html)
+            self.assertIn(str(err), html)
+
+    def test_text(self):
+        try:
+            raise ValueError("Hello World")
+        except ValueError as err:
+            text = cgitb.text(sys.exc_info())
+            self.assertIn("ValueError", text)
+            self.assertIn("Hello World", text)
+            
+    def test_hook(self):
+        proc = subprocess.Popen([sys.executable, '-c',
+                                 ('import cgitb;' 
+                                  'cgitb.enable();' 
+                                  'raise ValueError("Hello World")')],
+                                stdout=subprocess.PIPE)
+        out = proc.stdout.read().decode(sys.getfilesystemencoding())
+        self.addCleanup(proc.stdout.close)
+        self.assertIn("ValueError", out)
+        self.assertIn("Hello World", out)
+
+
+def test_main():
+    run_unittest(TestCgitb)
+    
+if __name__ == "__main__":
+    test_main()

Misc/ACKS

@@ -175,6 +175,7 @@ David Cinege
 Mike Clarkson
 Andrew Clegg
 Brad Clements
+Robbie Clemons
 Steve Clift
 Nick Coghlan
 Josh Cogliati

Misc/NEWS

@@ -994,6 +994,8 @@ Extension Modules
 Tests
 -----
 
+- Issue #11512: Add a test suite for the cgitb module. Patch by Robbie Clemons.
+
 - Issue #12497: Install test/data to prevent failures of the various codecmaps
   tests.