Implcit binding + lazy evaluation instead of storing context in Raven

index.js

@@ -8,16 +8,15 @@ function createRavenMiddleware(Raven, options = {}) {
     stateTransformer = identity,
     breadcrumbCategory = "redux-action"
   } = options;
-  Raven.setDataCallback((data, original) => {
-    data.extra.lastAction = actionTransformer(data.extra.lastAction);
-    data.extra.state = stateTransformer(data.extra.state);
-    return original ? original(data) : data;
-  });
+
   return store => {
-    // Record the initial state in case we crash before the first action
-    // succeeds.
-    // TODO: This does not currently work.
-    Raven.setExtraContext({ state: store.getState() });
+    let lastAction;
+
+    Raven.setDataCallback((data, original) => {
+      data.extra.lastAction = actionTransformer(lastAction);
+      data.extra.state = stateTransformer(store.getState());
+      return original ? original(data) : data;
+    });
 
     return next => action => {
       // Log the action taken to Raven so that we have narrative context in our
@@ -28,17 +27,8 @@ function createRavenMiddleware(Raven, options = {}) {
         data: breadcrumbDataFromAction(action)
       });
 
-      // Set the action as context in case we crash in the reducer.
-      const extra = { lastAction: action };
-      const returnValue = Raven.context({ extra }, () => next(action));
-
-      // Set the last action and state as context in case we crash before
-      // the next action is dispatched.
-      Raven.setExtraContext({
-        lastAction: action,
-        state: store.getState()
-      });
-      return returnValue;
+      lastAction = action;
+      return next(action);
     };
   };
 }

index.test.js

@@ -4,12 +4,16 @@ const { createStore, applyMiddleware } = require("redux");
 
 Raven.config("https://5d5bf17b1bed4afc9103b5a09634775e@sentry.io/146969", {
   allowDuplicates: true
-});
+}).install();
 
 const reducer = (previousState = 0, action) => {
   switch (action.type) {
     case "THROW":
-      throw new Error("Reducer error");
+      // Raven does not seem to be able to capture global exceptions in Jest tests.
+      // So we explicitly wrap this error in a Raven context.
+      Raven.context(() => {
+        throw new Error("Reducer error");
+      });
     case "INCREMENT":
       return previousState + 1;
     case "DOUBLE":