test: cover the background/foreground socket resume path

app/lib/store/__tests__/appStateMiddleware.test.ts

@@ -0,0 +1,93 @@
+jest.mock('react-native', () => ({
+	AppState: {
+		currentState: 'unknown',
+		addEventListener: jest.fn()
+	}
+}));
+
+jest.mock('../../notifications', () => ({
+	removeNotificationsAndBadge: jest.fn(() => Promise.resolve())
+}));
+
+import { AppState } from 'react-native';
+
+import applyAppStateMiddleware from '../appStateMiddleware';
+import { APP_STATE } from '../../../actions/actionsTypes';
+
+function bootMiddleware(): { dispatch: jest.Mock; notifyAppState: (state: string) => void } {
+	const dispatch = jest.fn();
+	const createStore = jest.fn(() => ({ dispatch }));
+	applyAppStateMiddleware()(createStore)();
+	const [, notifyAppState] = (AppState.addEventListener as jest.Mock).mock.calls[0];
+	jest.runOnlyPendingTimers();
+	return { dispatch, notifyAppState };
+}
+
+function dispatchedTypes(dispatch: jest.Mock): string[] {
+	return dispatch.mock.calls.map(([action]) => action.type);
+}
+
+describe('appStateMiddleware', () => {
+	beforeEach(() => {
+		jest.useFakeTimers();
+		jest.clearAllMocks();
+		AppState.currentState = 'unknown';
+	});
+
+	afterEach(() => {
+		jest.useRealTimers();
+	});
+
+	it('reports the state the app booted into', () => {
+		AppState.currentState = 'active';
+
+		const { dispatch } = bootMiddleware();
+
+		expect(dispatchedTypes(dispatch)).toEqual([APP_STATE.FOREGROUND]);
+	});
+
+	it('stays quiet when the app boots into an unknown state', () => {
+		AppState.currentState = 'unknown';
+
+		const { dispatch } = bootMiddleware();
+
+		expect(dispatchedTypes(dispatch)).toEqual([]);
+	});
+
+	it('tells the app it came to the foreground', () => {
+		const { dispatch, notifyAppState } = bootMiddleware();
+
+		notifyAppState('active');
+
+		expect(dispatchedTypes(dispatch)).toEqual([APP_STATE.FOREGROUND]);
+	});
+
+	it('tells the app it went to the background', () => {
+		const { dispatch, notifyAppState } = bootMiddleware();
+
+		notifyAppState('background');
+
+		expect(dispatchedTypes(dispatch)).toEqual([APP_STATE.BACKGROUND]);
+	});
+
+	it('keeps the foreground state through a temporary interruption', () => {
+		const { dispatch, notifyAppState } = bootMiddleware();
+
+		notifyAppState('active');
+		notifyAppState('inactive');
+		notifyAppState('active');
+
+		expect(dispatchedTypes(dispatch)).toEqual([APP_STATE.FOREGROUND]);
+	});
+
+	it('does not repeat the state already in effect', () => {
+		const { dispatch, notifyAppState } = bootMiddleware();
+
+		notifyAppState('background');
+		notifyAppState('background');
+		notifyAppState('active');
+		notifyAppState('active');
+
+		expect(dispatchedTypes(dispatch)).toEqual([APP_STATE.BACKGROUND, APP_STATE.FOREGROUND]);
+	});
+});

app/lib/testUtils/sdkIntegration.ts

@@ -58,6 +58,10 @@ export interface ISdkDriver {
 	};
 }
 
+export function latestConnection(connections: MockConnection[]): MockConnection {
+	return connections[connections.length - 1];
+}
+
 export function framesOn(connection: MockConnection, msg: string): IDdpMessage[] {
 	return connection.send.mock.calls
 		.map(([frame]: [string]) => JSON.parse(frame) as IDdpMessage)
@@ -129,6 +133,13 @@ export async function flush(turns = 10): Promise<void> {
 	}
 }
 
+export async function settleUntil(isSettled: () => boolean, maxRounds = 20): Promise<void> {
+	for (let round = 0; round < maxRounds && !isSettled(); round++) {
+		await jest.runOnlyPendingTimersAsync();
+		await flush();
+	}
+}
+
 export interface IMockReduxState {
 	meteor: { connected: boolean };
 	login: { user: Record<string, unknown> | null; isAuthenticated: boolean };