Add test for header in Saml2 plugin

This patch adds tests for https://review.openstack.org/#/c/420970/,
with this, we can be more confident that regressions won't easily
happen again in the future.

Change-Id: I40ebc795266b8fe4a191c543f6fadeefac661d2a
Related-Bug: 1656946

keystoneauth1/tests/unit/extras/saml2/test_auth_saml2.py

@@ -23,7 +23,8 @@ from keystoneauth1.tests.unit.extras.saml2 import fixtures as saml2_fixtures
 from keystoneauth1.tests.unit.extras.saml2 import utils
 from keystoneauth1.tests.unit import matchers
 
-PAOS_HEADER = {'Content-Type': 'application/vnd.paos+xml'}
+PAOS_HEADER = 'application/vnd.paos+xml'
+CONTENT_TYPE_PAOS_HEADER = {'Content-Type': PAOS_HEADER}
 InvalidResponse = saml2.v3.saml2.InvalidResponse
 
 
@@ -34,6 +35,8 @@ class SamlAuth2PluginTests(utils.TestCase):
     extracted into it's own module.
     """
 
+    HEADER_MEDIA_TYPE_SEPARATOR = ','
+
     TEST_USER = 'user'
     TEST_PASS = 'pass'
     TEST_SP_URL = 'http://sp.test'
@@ -53,12 +56,31 @@ class SamlAuth2PluginTests(utils.TestCase):
         user_pass = ('%s:%s' % (username, password)).encode('utf-8')
         return 'Basic %s' % base64.b64encode(user_pass).decode('utf-8')
 
+    def test_request_accept_headers(self):
+        # Include some random Accept header
+        random_header = uuid.uuid4().hex
+        headers = {'Accept': random_header}
+        req = requests.Request('GET', 'http://another.test', headers=headers)
+
+        plugin = self.get_plugin()
+        plugin_headers = plugin(req).headers
+        self.assertIn('Accept', plugin_headers)
+
+        # Since we have included a random Accept header, the plugin should have
+        # added the PAOS_HEADER to it using the correct media type separator
+        accept_header = plugin_headers['Accept']
+        self.assertIn(self.HEADER_MEDIA_TYPE_SEPARATOR, accept_header)
+        self.assertIn(random_header,
+                      accept_header.split(self.HEADER_MEDIA_TYPE_SEPARATOR))
+        self.assertIn(PAOS_HEADER,
+                      accept_header.split(self.HEADER_MEDIA_TYPE_SEPARATOR))
+
     def test_passed_when_not_200(self):
         text = uuid.uuid4().hex
         test_url = 'http://another.test'
         self.requests_mock.get(test_url,
                                status_code=201,
-                               headers=PAOS_HEADER,
+                               headers=CONTENT_TYPE_PAOS_HEADER,
                                text=text)
 
         resp = requests.get(test_url, auth=self.get_plugin())
@@ -78,7 +100,7 @@ class SamlAuth2PluginTests(utils.TestCase):
         text = uuid.uuid4().hex
 
         self.requests_mock.get(self.TEST_SP_URL, response_list=[
-            dict(headers=PAOS_HEADER,
+            dict(headers=CONTENT_TYPE_PAOS_HEADER,
                  content=utils.make_oneline(saml2_fixtures.SP_SOAP_RESPONSE)),
             dict(text=text)
         ])
@@ -111,7 +133,7 @@ class SamlAuth2PluginTests(utils.TestCase):
         text = uuid.uuid4().hex
 
         self.requests_mock.get(self.TEST_SP_URL, response_list=[
-            dict(headers=PAOS_HEADER,
+            dict(headers=CONTENT_TYPE_PAOS_HEADER,
                  content=utils.make_oneline(saml2_fixtures.SP_SOAP_RESPONSE)),
             dict(text=text)
         ])
@@ -146,7 +168,7 @@ class SamlAuth2PluginTests(utils.TestCase):
     def test_initial_sp_call_invalid_response(self):
         """Send initial SP HTTP request and receive wrong server response."""
         self.requests_mock.get(self.TEST_SP_URL,
-                               headers=PAOS_HEADER,
+                               headers=CONTENT_TYPE_PAOS_HEADER,
                                text='NON XML RESPONSE')
 
         self.assertRaises(InvalidResponse,
@@ -163,7 +185,7 @@ class SamlAuth2PluginTests(utils.TestCase):
         saml_assertion = saml2_fixtures.saml_assertion(destination=consumer2)
 
         self.requests_mock.get(self.TEST_SP_URL,
-                               headers=PAOS_HEADER,
+                               headers=CONTENT_TYPE_PAOS_HEADER,
                                content=soap_response)
 
         self.requests_mock.post(self.TEST_IDP_URL, content=saml_assertion)
@@ -226,7 +248,7 @@ class AuthenticateviaSAML2Tests(utils.TestCase):
         token = ksa_fixtures.V3Token()
 
         self.requests_mock.get(self.default_sp_url, response_list=[
-            dict(headers=PAOS_HEADER,
+            dict(headers=CONTENT_TYPE_PAOS_HEADER,
                  content=utils.make_oneline(saml2_fixtures.SP_SOAP_RESPONSE)),
             dict(headers={'X-Subject-Token': token_id}, json=token)
         ])
@@ -263,7 +285,7 @@ class AuthenticateviaSAML2Tests(utils.TestCase):
         saml_assertion = saml2_fixtures.saml_assertion(destination=consumer2)
 
         self.requests_mock.get(self.default_sp_url,
-                               headers=PAOS_HEADER,
+                               headers=CONTENT_TYPE_PAOS_HEADER,
                                content=soap_response)
 
         self.requests_mock.post(self.TEST_IDP_URL, content=saml_assertion)
@@ -280,7 +302,7 @@ class AuthenticateviaSAML2Tests(utils.TestCase):
     def test_initial_sp_call_invalid_response(self):
         """Send initial SP HTTP request and receive wrong server response."""
         self.requests_mock.get(self.default_sp_url,
-                               headers=PAOS_HEADER,
+                               headers=CONTENT_TYPE_PAOS_HEADER,
                                text='NON XML RESPONSE')
 
         self.assertRaises(exceptions.AuthorizationFailure,