First API tests.

crates/jmap/src/changes/mod.rs

@@ -0,0 +1,27 @@
+use jmap_proto::{
+    error::method::MethodError,
+    types::{collection::Collection, state::State},
+};
+
+use crate::JMAP;
+
+impl JMAP {
+    pub async fn get_state(
+        &self,
+        account_id: u32,
+        collection: Collection,
+    ) -> Result<State, MethodError> {
+        match self.store.get_last_change_id(account_id, collection).await {
+            Ok(id) => Ok(id.into()),
+            Err(err) => {
+                tracing::error!(event = "error",
+                    context = "store",
+                    account_id = account_id,
+                    collection = ?collection,
+                    error = ?err,
+                    "Failed to obtain state");
+                Err(MethodError::ServerPartialFail)
+            }
+        }
+    }
+}