Explicitly install nested DevTools extension dependencies for tests

Author: Brian Vaughn

scripts/jest/jest-cli.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const {spawn} = require('child_process');
+const {spawn, spawnSync} = require('child_process');
 const chalk = require('chalk');
 const yargs = require('yargs');
 const fs = require('fs');
@@ -310,6 +310,25 @@ function main() {
   const args = getCommandArgs();
   const envars = getEnvars();
 
+  if (argv.project === 'devtools') {
+    console.log(
+      chalk.blue(
+        `\nInstalling Yarn dependencies for nested react-devtools-extensions package ...`
+      )
+    );
+
+    spawnSync('yarn install', {
+      stdio: 'inherit',
+      cwd: path.join(
+        __dirname,
+        '..',
+        '..',
+        'packages',
+        'react-devtools-extensions'
+      ),
+    });
+  }
+
   // Print the full command we're actually running.
   console.log(
     chalk.dim(