fix(plus): user subscription transitions (#417)

* database migration, deprecations

* implement sub state transition recording, test scaffolding

* implement a helper function to encode webhook payloads

* mores tests, moved fixtures around, amended docs for new set_token helper

* tracking some master changes

* Fix a problem with unknown capabilities getting passed in from the subscription change webhook

* Skip creating a new vector, get the first element directly from the iterator.

* Follow Clippy's hints

src/db/fxa_webhook.rs

@@ -8,7 +8,7 @@ use crate::db::settings::create_or_update_settings;
 use crate::db::types::FxaEvent;
 use crate::db::users::get_user_opt;
 use crate::db::{schema, Pool};
-use crate::fxa::LoginManager;
+use crate::fxa::{self, LoginManager};
 use actix_rt::ArbiterHandle;
 use actix_web::web;
 use basket::Basket;
@@ -185,9 +185,16 @@ pub async fn update_subscription_state_from_webhook(
                 .values(fxa_event)
                 .returning(schema::webhook_events::id)
                 .get_result::<i64>(&mut conn)?;
-            let subscription: Subscription = match (update.is_active, update.capabilities.first()) {
+            // Filter out any unknown subscription types we get passed in
+            // before we try to get the interesting first element of the
+            // capabilities array.
+            let capability = update
+                .capabilities
+                .into_iter()
+                .find(|&c| c != fxa::types::Subscription::Unknown);
+            let subscription: Subscription = match (update.is_active, capability) {
                 (false, _) => Subscription::Core,
-                (true, Some(c)) => Subscription::from(*c),
+                (true, Some(c)) => Subscription::from(c),
                 (true, None) => Subscription::Core,
             };
             if subscription == Subscription::Core {

tests/api/fxa_webhooks.rs

@@ -414,17 +414,20 @@ async fn record_subscription_state_transitions_test() -> Result<(), Error> {
         );
     }
 
-    // Now create a later transition to 10m and check the table again
+    // Now create a later transition to 10m and check the table again.
     {
         let json_str = std::fs::read_to_string(
             "tests/data/set_tokens/set_token_subscription_state_change_to_10m.json",
         )
         .unwrap();
         let mut claim: Value = serde_json::from_str(&json_str).unwrap();
-        // add time to the event to be sure it is after the previous event
+        // Add some time to the event to be sure it is after the previous event.
         claim["iat"] = json!(1654425317000i64 + 300000);
         claim["events"]["https://schemas.accounts.firefox.com/event/subscription-state-change"]
             ["changeTime"] = json!(1654425317000i64 + 300000);
+        // We also add some unknown capability to the event to check that they are ignored correctly.
+        claim["events"]["https://schemas.accounts.firefox.com/event/subscription-state-change"]
+            ["capabilities"] = json!(["something_unknown", "mdn_plus_10m"]);
         let set_token = token_from_claim(&claim);
 
         let res = logged_in_client.trigger_webhook(&set_token).await;