ANDROID_SDK_ROOT support (#2106)

Summary:
According to Google, ANDROID_HOME is deprecated.
This means, that having only ANDROID_SDK_ROOT as environment variable leading to Android SDK is enough.
Flipper supports only ANDROID_HOME, so I would like to add ANDROID_SDK_ROOT support.
However, there is a set of rules of ANDROID_HOME and ANDROID_SDK_ROOT priority.
Everything is mentioned on a this page: https://developer.android.com/studio/command-line/variables

## Changelog
Added ANDROID_SDK_ROOT environment variable support

Pull Request resolved: https://github.com/facebook/flipper/pull/2106

Test Plan: Probably I would need a help with this

Reviewed By: mweststrate

Differential Revision: D27505024

Pulled By: passy

fbshipit-source-id: 8bdc66a9652c673fd44944d87af1efc9e93d0f1b

desktop/app/src/dispatcher/androidDevice.tsx

@@ -138,7 +138,12 @@ export default (store: Store, logger: Logger) => {
   const watchAndroidDevices = () => {
     // get emulators
     promisify(which)('emulator')
-      .catch(() => `${process.env.ANDROID_HOME || ''}/tools/emulator`)
+      .catch(
+        () =>
+          `${
+            process.env.ANDROID_HOME || process.env.ANDROID_SDK_ROOT || ''
+          }/tools/emulator`,
+      )
       .then((emulatorPath) => {
         child_process.exec(
           `${emulatorPath} -list-avds`,

desktop/app/src/init.tsx

@@ -162,7 +162,7 @@ function setProcessState(store: Store) {
   const androidHome = settings.androidHome;
   const idbPath = settings.idbPath;
 
-  if (!process.env.ANDROID_HOME) {
+  if (!process.env.ANDROID_HOME && !process.env.ANDROID_SDK_ROOT) {
     process.env.ANDROID_HOME = androidHome;
   }
 

desktop/doctor/src/index.ts

@@ -46,10 +46,10 @@ export type Healthcheck = {
   run: (
     env: EnvironmentInfo,
     settings?: Settings,
-  ) => Promise<HealthchecRunResult>;
+  ) => Promise<HealthcheckRunResult>;
 };
 
-export type HealthchecRunResult = {
+export type HealthcheckRunResult = {
   hasProblem: boolean;
   message: string;
 };
@@ -114,26 +114,65 @@ export function getHealthchecks(): Healthchecks {
           label: 'SDK Installed',
           isRequired: true,
           run: async (_: EnvironmentInfo) => {
-            if (process.env.ANDROID_HOME) {
-              const androidHome = process.env.ANDROID_HOME;
-              if (!fs.existsSync(androidHome)) {
-                return {
-                  hasProblem: true,
-                  message: `ANDROID_HOME points to a folder which does not exist: ${androidHome}. You can use Flipper Settings (File > Preferences) to point to a different location.`,
-                };
-              }
+            const androidHome = process.env.ANDROID_HOME;
+            const androidSdkRoot = process.env.ANDROID_SDK_ROOT;
+
+            let androidHomeResult: HealthcheckRunResult;
+            if (!androidHome) {
+              androidHomeResult = {
+                hasProblem: true,
+                message: `ANDROID_HOME is not defined. You can use Flipper Settings (File > Preferences) to point to its location.`,
+              };
+            } else if (!fs.existsSync(androidHome)) {
+              androidHomeResult = {
+                hasProblem: true,
+                message: `ANDROID_HOME point to a folder which does not exist: ${androidHome}. You can use Flipper Settings (File > Preferences) to point to a different location.`,
+              };
+            } else {
               const platformToolsDir = path.join(androidHome, 'platform-tools');
-              if (!fs.existsSync(path.join(androidHome, 'platform-tools'))) {
-                return {
+              if (!fs.existsSync(platformToolsDir)) {
+                androidHomeResult = {
                   hasProblem: true,
                   message: `Android SDK Platform Tools not found at the expected location "${platformToolsDir}". Probably they are not installed.`,
                 };
+              } else {
+                androidHomeResult = await tryExecuteCommand(
+                  `"${path.join(platformToolsDir, 'adb')}" version`,
+                );
               }
-              return await tryExecuteCommand(
-                `"${path.join(platformToolsDir, 'adb')}" version`,
-              );
             }
-            return await tryExecuteCommand('adb version');
+            if (androidHomeResult.hasProblem == false) {
+              return androidHomeResult;
+            }
+
+            let androidSdkRootResult: HealthcheckRunResult;
+            if (!androidSdkRoot) {
+              androidSdkRootResult = {
+                hasProblem: true,
+                message: `ANDROID_SDK_ROOT is not defined. You can use Flipper Settings (File > Preferences) to point to its location.`,
+              };
+            } else if (!fs.existsSync(androidSdkRoot)) {
+              androidSdkRootResult = {
+                hasProblem: true,
+                message: `ANDROID_SDK_ROOT point to a folder which does not exist: ${androidSdkRoot}. You can use Flipper Settings (File > Preferences) to point to a different location.`,
+              };
+            } else {
+              const platformToolsDir = path.join(
+                androidSdkRoot,
+                'platform-tools',
+              );
+              if (!fs.existsSync(platformToolsDir)) {
+                androidSdkRootResult = {
+                  hasProblem: true,
+                  message: `Android SDK Platform Tools not found at the expected location "${platformToolsDir}". Probably they are not installed.`,
+                };
+              } else {
+                androidSdkRootResult = await tryExecuteCommand(
+                  `"${path.join(platformToolsDir, 'adb')}" version`,
+                );
+              }
+            }
+            return androidSdkRootResult;
           },
         },
       ],
@@ -299,7 +338,7 @@ export async function runHealthchecks(): Promise<
 
 async function tryExecuteCommand(
   command: string,
-): Promise<HealthchecRunResult> {
+): Promise<HealthcheckRunResult> {
   try {
     const output = await promisify(exec)(command);
     return {