Automatically remove 'past' and 'future' history from redux-undo

Author: ndbroadbent

index.js

@@ -1,12 +1,45 @@
 const identity = x => x;
 const getUndefined = () => {};
 const filter = () => true;
+// Include a heuristic to remove redux-undo history (https://github.com/omnidan/redux-undo)
+// 'past' and 'future' are arrays that can include a large number of copies of the state.
+const removeHistoryFromObject = obj =>
+  Object.assign({}, obj, {
+    past: `redux-undo history was automatically removed. (Entries: ${
+      obj.past.length
+    })`,
+    future: `redux-undo history was automatically removed. (Entries: ${
+      obj.future.length
+    })`
+  });
+const isReduxUndoState = state =>
+  state &&
+  state.past &&
+  state.present &&
+  state.future &&
+  typeof state.index === "number" &&
+  typeof state.limit === "number";
+const removeReduxUndoHistoryFromState = state => {
+  if (!state || typeof state !== "object") return state;
+  if (isReduxUndoState(state)) {
+    return removeHistoryFromObject(state);
+  }
+  let newState = null;
+  Object.entries(state).forEach(([key, store]) => {
+    if (isReduxUndoState(store)) {
+      if (!newState) newState = Object.assign({}, state);
+      newState[key] = removeHistoryFromObject(store);
+    }
+  });
+  return newState || state;
+};
+
 function createRavenMiddleware(Raven, options = {}) {
   // TODO: Validate options.
   const {
     breadcrumbDataFromAction = getUndefined,
     actionTransformer = identity,
-    stateTransformer = identity,
+    stateTransformer = removeReduxUndoHistoryFromState,
     breadcrumbCategory = "redux-action",
     filterBreadcrumbActions = filter,
     getUserContext,

index.test.js

@@ -6,7 +6,12 @@ Raven.config("https://[email protected]/146969", {
   allowDuplicates: true
 }).install();
 
-const reducer = (previousState = { value: 0 }, action) => {
+const defaultState = { value: 0 };
+const context = {
+  initialState: defaultState
+};
+
+const reducer = (previousState = context.initialState, action) => {
   switch (action.type) {
     case "THROW":
       // Raven does not seem to be able to capture global exceptions in Jest tests.
@@ -23,11 +28,10 @@ const reducer = (previousState = { value: 0 }, action) => {
   }
 };
 
-const context = {};
-
 describe("raven-for-redux", () => {
   beforeEach(() => {
     context.mockTransport = jest.fn();
+    context.initialState = defaultState;
     Raven.setTransport(context.mockTransport);
     Raven.setDataCallback(undefined);
     Raven.setBreadcrumbCallback(undefined);
@@ -186,6 +190,93 @@ describe("raven-for-redux", () => {
         userData
       );
     });
+    describe("with redux-undo history as top-level state", () => {
+      beforeEach(() => {
+        context.initialState = {
+          past: [{ value: 2 }, { value: 1 }],
+          present: { value: 0 },
+          future: [],
+          index: 2,
+          limit: 2
+        };
+        context.store = createStore(
+          reducer,
+          applyMiddleware(context.middleware)
+        );
+      });
+      it("replaces the past and future arrays in the state", () => {
+        expect(() => {
+          context.store.dispatch({ type: "THROW" });
+        }).toThrow();
+
+        expect(context.mockTransport).toHaveBeenCalledTimes(1);
+        const { extra } = context.mockTransport.mock.calls[0][0].data;
+        expect(extra.state).toEqual({
+          past: "redux-undo history was automatically removed. (Entries: 2)",
+          present: { value: 0 },
+          future: "redux-undo history was automatically removed. (Entries: 0)",
+          index: 2,
+          limit: 2
+        });
+      });
+    });
+    describe("with redux-undo history as nested stores", () => {
+      beforeEach(() => {
+        context.initialState = {
+          fooStore: {
+            past: [{ value: 2 }, { value: 1 }],
+            present: { value: 0 },
+            future: [],
+            index: 2,
+            limit: 2
+          },
+          barStore: {
+            value: 2
+          }
+        };
+        context.store = createStore(
+          reducer,
+          applyMiddleware(context.middleware)
+        );
+      });
+      it("replaces past and future arrays in any nested stores that use redux-undo", () => {
+        expect(() => {
+          context.store.dispatch({ type: "THROW" });
+        }).toThrow();
+        expect(context.mockTransport).toHaveBeenCalledTimes(1);
+        const { extra } = context.mockTransport.mock.calls[0][0].data;
+        expect(extra.state).toEqual({
+          fooStore: {
+            past: "redux-undo history was automatically removed. (Entries: 2)",
+            present: { value: 0 },
+            future:
+              "redux-undo history was automatically removed. (Entries: 0)",
+            index: 2,
+            limit: 2
+          },
+          barStore: {
+            value: 2
+          }
+        });
+      });
+    });
+    describe("with state that is not an object", () => {
+      beforeEach(() => {
+        context.initialState = 42;
+        context.store = createStore(
+          reducer,
+          applyMiddleware(context.middleware)
+        );
+      });
+      it("does not affect the state", () => {
+        expect(() => {
+          context.store.dispatch({ type: "THROW" });
+        }).toThrow();
+        expect(context.mockTransport).toHaveBeenCalledTimes(1);
+        const { extra } = context.mockTransport.mock.calls[0][0].data;
+        expect(extra.state).toEqual(42);
+      });
+    });
   });
   describe("with all the options enabled", () => {
     beforeEach(() => {