another patch from Brent Hendricks to add new handlers with the various

* python/generator.py python/libxml.py: another patch from Brent
  Hendricks to add new handlers with the various validity contexts
* python/tests/Makefile.am python/tests/validDTD.py
  python/tests/validRNG.py python/tests/validSchemas.py: also
  added the regression tests he provided
Daniel

python/tests/validDTD.py

@@ -0,0 +1,59 @@
+#!/usr/bin/python -u
+import libxml2
+import sys
+
+ARG = 'test string'
+
+class ErrorHandler:
+
+    def __init__(self):
+        self.errors = []
+
+    def handler(self, msg, data):
+        if data != ARG:
+            raise Exception, "Error handler did not receive correct argument"
+        self.errors.append(msg)
+
+
+# Memory debug specific
+libxml2.debugMemory(1)
+
+dtd="""<!ELEMENT foo EMPTY>"""
+valid="""<?xml version="1.0"?>
+<foo></foo>"""
+
+invalid="""<?xml version="1.0"?>
+<foo><bar/></foo>"""
+
+dtd = libxml2.parseDTD(None, 'test.dtd')
+ctxt = libxml2.newValidCtxt()
+e = ErrorHandler()
+ctxt.setValidityErrorHandler(e.handler, e.handler, ARG)
+
+# Test valid document
+doc = libxml2.parseDoc(valid)
+ret = doc.validateDtd(ctxt, dtd)
+if ret != 1 or e.errors:
+    print "error doing DTD validation"
+    sys.exit(1)
+doc.freeDoc()
+
+# Test invalid document
+doc = libxml2.parseDoc(invalid)
+ret = doc.validateDtd(ctxt, dtd)
+if ret != 0 or not e.errors:
+    print "Error: document supposed to be invalid"
+doc.freeDoc()
+
+dtd.freeDtd()
+del dtd
+del ctxt
+
+# Memory debug specific
+libxml2.cleanupParser()
+if libxml2.debugMemory(1) == 0:
+    print "OK"
+else:
+    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
+    libxml2.dumpMemory()
+