Always specify a preset (#166)

* Always specify a preset

Synapse and Dendrite disagree what the join rules are if this is omitted.
Dendrite follows the spec, Synapse doesn't. Nontheless, we should be
specific in tests.

* Don't use map[string]interface{}

Whilst most of the time this is fine, it isn't in v1 paths which
return `[$status_code, $json_object]`. Use `interface{}` instead.

* Set public_chat on knocking msc

tests/federation_room_join_test.go

@@ -290,7 +290,9 @@ func TestCannotSendNonLeaveViaSendLeaveV2(t *testing.T) {
 // and checks that they are all rejected.
 func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expectedMembership string, createRoomOpts map[string]interface{}) {
 	if createRoomOpts == nil {
-		createRoomOpts = make(map[string]interface{})
+		createRoomOpts = map[string]interface{}{
+			"preset": "public_chat",
+		}
 	}
 
 	deployment := Deploy(t, b.BlueprintAlice)
@@ -324,7 +326,7 @@ func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expected
 			return
 		}
 
-		var res map[string]interface{}
+		var res interface{}
 		err := srv.SendFederationRequest(deployment, req, &res)
 		if err == nil {
 			t.Errorf("send request returned 200")

tests/msc2403_test.go

@@ -473,6 +473,7 @@ func publishAndCheckRoomJoinRule(t *testing.T, c *client.CSAPI, roomID, expected
 func TestCannotSendNonKnockViaSendKnock(t *testing.T) {
 	testValidationForSendMembershipEndpoint(t, "/_matrix/federation/v1/send_knock", "knock",
 		map[string]interface{}{
+			"preset":       "public_chat",
 			"room_version": "7",
 		},
 	)