Add device flow scope. (#616)

add the openid as the base scope

client/internal/oauth_test.go

@@ -59,9 +59,11 @@ func TestHosted_RequestDeviceCode(t *testing.T) {
 
 	expectedAudience := "ok"
 	expectedClientID := "bla"
+	expectedScope := "openid"
 	form := url.Values{}
 	form.Add("audience", expectedAudience)
 	form.Add("client_id", expectedClientID)
+	form.Add("scope", expectedScope)
 	expectPayload := form.Encode()
 
 	testCase1 := test{
@@ -113,6 +115,7 @@ func TestHosted_RequestDeviceCode(t *testing.T) {
 			hosted := Hosted{
 				Audience:           expectedAudience,
 				ClientID:           expectedClientID,
+				Scope:              expectedScope,
 				TokenEndpoint:      "test.hosted.com/token",
 				DeviceAuthEndpoint: "test.hosted.com/device/auth",
 				HTTPClient:         &httpClient,