jest: Add and use jest-expo preset, again.

Done to reduce boring mocks (in particular, remove boring mocks for
things from Expo) in our Jest setup.

A redo of 62621ef and e40c020, reverted in 347aa96, which we
can do following the recent RN upgrade to v0.62 (see 347aa96 for
details).

Since we're on [email protected], use 16.11.0 as the version range for
react-dom, instead of 16.9.0 as we did in 62621ef. (We don't use
any code in react-dom, but we unfortunately have to include it to
satisfy peer dependencies; see 62621ef.)

This time around, we get a peer-dependency warning suggesting we
need to install expo-splash-screen:

"""
warning "jest-expo > @expo/config >
@expo/[email protected]" has unmet peer dependency
"expo-splash-screen@*".
"""

So, do that. It really should go under `devDependencies`, since we
only need it for jest-expo. But I find that react-native-unimodules
is automatically linking `expo-splash-screen`'s native code on iOS
and Android, whether it's in `devDependencies` or `dependencies`.
Although I didn't encounter problems building and running for
release on iOS or Android with it in `devDependencies`, it seems
problematic to link native code from a package we've said is for
development only. So, reluctantly, say that it's not for development
only, by putting it under `dependencies`. We may in fact want to use
it in production one day; if we do, we'll probably need to put
together a Flow libdef.

[1] We can't do the usual thing to prevent it from getting linked,
    adding lines to `react-native.config.js`. It seems Unimodules
    isn't informed by that file, which is where React Native's
    autolinking (a separate process) takes its cues from.

    There may be a way to tell Unimodules to exclude it, but it
    seems to mean calling code in two or three places that's mostly
    meant for internal use; see
    https://forums.expo.io/t/unimodules-what-else-can-i-exclude/41079
    and
    expo/expo#9736 (comment).

android/app/src/main/java/com/zulipmobile/generated/BasePackageList.java

@@ -12,7 +12,8 @@ public List<Package> getPackageList() {
         new expo.modules.filesystem.FileSystemPackage(),
         new expo.modules.imageloader.ImageLoaderPackage(),
         new expo.modules.permissions.PermissionsPackage(),
-        new expo.modules.screenorientation.ScreenOrientationPackage()
+        new expo.modules.screenorientation.ScreenOrientationPackage(),
+        new expo.modules.splashscreen.SplashScreenPackage()
     );
   }
 }

ios/Podfile.lock

@@ -23,6 +23,9 @@ PODS:
   - EXScreenOrientation (1.0.0):
     - React-Core
     - UMCore
+  - EXSplashScreen (0.5.0):
+    - React
+    - UMCore
   - FBLazyVector (0.62.2)
   - FBReactNativeSpec (0.62.2):
     - Folly (= 2018.10.22.00)
@@ -402,6 +405,7 @@ DEPENDENCIES:
   - EXImageLoader (from `../node_modules/expo-image-loader/ios`)
   - EXPermissions (from `../node_modules/expo-permissions/ios`)
   - EXScreenOrientation (from `../node_modules/expo-screen-orientation/ios`)
+  - EXSplashScreen (from `../node_modules/expo-splash-screen/ios`)
   - FBLazyVector (from `../node_modules/react-native/Libraries/FBLazyVector`)
   - FBReactNativeSpec (from `../node_modules/react-native/Libraries/FBReactNativeSpec`)
   - Flipper (~> 0.33.1)
@@ -516,6 +520,8 @@ EXTERNAL SOURCES:
     :path: "../node_modules/expo-permissions/ios"
   EXScreenOrientation:
     :path: "../node_modules/expo-screen-orientation/ios"
+  EXSplashScreen:
+    :path: "../node_modules/expo-splash-screen/ios"
   FBLazyVector:
     :path: "../node_modules/react-native/Libraries/FBLazyVector"
   FBReactNativeSpec:
@@ -643,6 +649,7 @@ SPEC CHECKSUMS:
   EXImageLoader: 5ad6896fa1ef2ee814b551873cbf7a7baccc694a
   EXPermissions: 24b97f734ce9172d245a5be38ad9ccfcb6135964
   EXScreenOrientation: 44d3cd3a99a86b9cb681e742697bc2c057d7fbd2
+  EXSplashScreen: 9423d258b71afa5bf128a83dcb57b636d9900a74
   FBLazyVector: 4aab18c93cd9546e4bfed752b4084585eca8b245
   FBReactNativeSpec: 5465d51ccfeecb7faa12f9ae0024f2044ce4044e
   Flipper: 6c1f484f9a88d30ab3e272800d53688439e50f69

jest.config.js

@@ -4,6 +4,7 @@
 // These will be used as regexp fragments.
 const transformModulesWhitelist = [
   'expo-apple-authentication',
+  'expo-application',
   'react-native',
   // @rnc/async-storage itself is precompiled, but its mock-helper is not
   '@react-native-community/async-storage',
@@ -24,7 +25,7 @@ const transformModulesWhitelist = [
 const transformIgnorePattern = `node_modules/(?!${transformModulesWhitelist.join('|')})`;
 
 module.exports = {
-  preset: 'react-native',
+  preset: 'jest-expo',
 
   // Finding and transforming source code.
 

jest/jestSetup.js

@@ -85,10 +85,6 @@ jest.mock('react-native-simple-toast', () => ({
   showWithGravity: jest.fn(),
 }));
 
-jest.mock('expo-application', () => ({
-  nativeApplicationVersion: '26.23.146',
-}));
-
 jest.mock('react-native-device-info', () => ({
   getSystemName: jest.fn().mockReturnValue('ios'),
   getSystemVersion: jest.fn().mockReturnValue('13.3.1'),
@@ -105,10 +101,3 @@ jest.mock('react-native-image-picker', () => ({
   launchCamera: jest.fn(),
   launchImageLibrary: jest.fn(),
 }));
-
-jest.mock('expo-apple-authentication', () => ({
-  AppleAuthenticationButton: jest.fn(),
-  isAvailableAsync: jest.fn(),
-  signInAsync: jest.fn(),
-  // etc. (incomplete)
-}));

package.json

@@ -47,6 +47,7 @@
     "expo-apple-authentication": "^2.1.1",
     "expo-application": "^2.1.1",
     "expo-screen-orientation": "^1.0.0",
+    "expo-splash-screen": "^0.5.0",
     "immutable": "^4.0.0-rc.12",
     "json-stringify-safe": "^5.0.1",
     "katex": "^0.11.1",
@@ -125,6 +126,7 @@
     "jest-cli": "^26.4.1",
     "jest-environment-jsdom": "^26.3.0",
     "jest-environment-jsdom-global": "^2.0.4",
+    "jest-expo": "^38.0.2",
     "jest-extended": "^0.11.5",
     "jetifier": "^1.6.5",
     "lolex": "^5.1.1",
@@ -133,7 +135,9 @@
     "prettier-eslint": "^11.0.0",
     "prettier-eslint-cli": "^5.0.0",
     "prop-types": "^15.7.2",
+    "react-dom": "16.11.0",
     "react-native-cli": "^2.0.1",
+    "react-native-web": "^0.13.3",
     "redux-mock-store": "^1.5.1",
     "rollup": "^2.26.5",
     "typescript": "^3.9.7",