promote HandshakeSettings._getCertificateTypes to public

the method is only used by external classes so it should be public

tlslite/handshakesettings.py

@@ -182,11 +182,12 @@ def validate(self):
 
         return other
 
-    def _getCertificateTypes(self):
-        l = []
+    def getCertificateTypes(self):
+        """Get list of certificate types as IDs"""
+        ret = []
         for ct in self.certificateTypes:
             if ct == "x509":
-                l.append(CertificateType.x509)
+                ret.append(CertificateType.x509)
             else:
                 raise AssertionError()
-        return l
+        return ret

tlslite/tlsconnection.py

@@ -514,7 +514,7 @@ def _clientSendClientHello(self, settings, session, srpUsername,
             wireCipherSuites.append(CipherSuite.TLS_FALLBACK_SCSV)
 
         #Initialize acceptable certificate types
-        certificateTypes = settings._getCertificateTypes()
+        certificateTypes = settings.getCertificateTypes()
 
         #Either send ClientHello (with a resumable session)...
         if session and session.sessionID:

unit_tests/test_tlslite_handshakesettings.py

@@ -140,3 +140,15 @@ def test_maxVersion_without_TLSv1_2(self):
         new_hs = hs.validate()
 
         self.assertFalse("sha256" in new_hs.macNames)
+
+    def test_getCertificateTypes(self):
+        hs = HandshakeSettings()
+
+        self.assertEqual([0], hs.getCertificateTypes())
+
+    def test_getCertificateTypes_with_unsupported_type(self):
+        hs = HandshakeSettings()
+        hs.certificateTypes = ["x509", "openpgp"]
+
+        with self.assertRaises(AssertionError):
+            hs.getCertificateTypes()