Revert "Poll for live data only when page is visible"

This reverts commit 8900bd5. We suspect
that this may be making more requests than it is meant to, and it's only
auxiliary to the cache in making the realtime endpoint more performant.

apps/site/assets/ts/schedule/__tests__/LineDiagramTest.tsx

@@ -1,5 +1,5 @@
 import React from "react";
-import { mount, ReactWrapper, shallow, ShallowWrapper } from "enzyme";
+import { mount, ReactWrapper } from "enzyme";
 import { cloneDeep, merge } from "lodash";
 import LineDiagram from "../components/line-diagram/LineDiagram";
 import { EnhancedRoute, RouteType } from "../../__v3api";
@@ -16,21 +16,12 @@ import simpleLiveData from "./lineDiagramData/live-data.json";
 const lineDiagram = (simpleLineDiagram as unknown) as LineDiagramStop[];
 let lineDiagramBranchingOut = (outwardLineDiagram as unknown) as LineDiagramStop[];
 
-// Mock useInterval to instead call the function immediately
-jest.mock("use-interval", () => {
-  return { useInterval: jest.fn((fn: () => void) => fn()) };
-});
-
-// Mock useFetch to return fixture data with a spy-able reload function
-const liveDataReload = jest.fn();
-const useFetch = jest.fn().mockImplementation(() => ({
-  data: simpleLiveData,
-  isLoading: false,
-  reload: liveDataReload
-}));
 jest.mock("react-async", () => {
-  return { useFetch: () => useFetch() };
+  return {
+    useFetch: jest.fn(() => ({ data: simpleLiveData, reload: () => {} }))
+  };
 });
+jest.mock("use-interval");
 
 const route = {
   type: 3 as RouteType,
@@ -355,72 +346,3 @@ describe("LineDiagram for CR with branches going inward", () => {
     expect(moreStops.exists()).toBeTruthy();
   });
 });
-
-describe("LineDiagram live data", () => {
-  const animationFrameSpy = jest.spyOn(window, "requestAnimationFrame");
-  const documentHiddenSpy = jest.spyOn(document, "hidden", "get");
-
-  let wrapper: ShallowWrapper;
-
-  const mountComponent = () => {
-    wrapper = shallow(
-      <LineDiagram
-        lineDiagram={lineDiagram}
-        route={route as EnhancedRoute}
-        directionId={directionId}
-        routePatternsByDirection={
-          routePatternsByDirection as RoutePatternsByDirection
-        }
-        services={[]}
-        stops={{ 0: stops, 1: stops }}
-        today="2019-12-05"
-        scheduleNote={null}
-      />
-    );
-  };
-
-  it("polls for live data using an animation frame request", () => {
-    animationFrameSpy.mockImplementation(fn => {
-      fn(0);
-      return 1;
-    });
-    mountComponent();
-
-    expect(liveDataReload).toHaveBeenCalledTimes(1);
-  });
-
-  it("does not poll for live data when no animation frame occurs", () => {
-    animationFrameSpy.mockImplementation(fn => {
-      return 1;
-    });
-    mountComponent();
-
-    expect(liveDataReload).not.toHaveBeenCalled();
-  });
-
-  it("does not poll for live data when the page is not visible", () => {
-    animationFrameSpy.mockImplementation(fn => {
-      fn(0);
-      return 1;
-    });
-    documentHiddenSpy.mockReturnValue(true);
-    mountComponent();
-
-    expect(liveDataReload).not.toHaveBeenCalled();
-  });
-
-  it("does not poll for live data when another request is in flight", () => {
-    animationFrameSpy.mockImplementation(fn => {
-      fn(0);
-      return 1;
-    });
-    useFetch.mockImplementationOnce(() => ({
-      data: {},
-      isLoading: true,
-      reload: liveDataReload
-    }));
-    mountComponent();
-
-    expect(liveDataReload).not.toHaveBeenCalled();
-  });
-});

apps/site/assets/ts/schedule/components/line-diagram/LineDiagram.tsx

@@ -1,6 +1,6 @@
 import React, { ReactElement, useState } from "react";
-import { useInterval } from "use-interval";
 import { useFetch } from "react-async";
+import { useInterval } from "use-interval";
 
 import {
   LineDiagramStop,
@@ -105,11 +105,9 @@ const LineDiagram = ({
     { json: true, watch: directionId }
   );
   const liveData = (maybeLiveData || {}) as LiveDataByStop;
-
   useInterval(() => {
-    requestAnimationFrame(() => {
-      if (!document.hidden && !liveDataIsLoading) reloadLiveData();
-    });
+    /* istanbul ignore next */
+    if (!liveDataIsLoading) reloadLiveData();
   }, 15000);
 
   const handleStopClick = (stop: RouteStop): void => {