fix(config): Adds support for --offline flag to global add command

CHANGELOG.md

@@ -4,6 +4,10 @@ Please add one entry in this file for each change in Yarn's behavior. Use the sa
 
 ## Master
 
+- Adds support for --offline flag to global add command
+
+  [#7330](https://github.com/yarnpkg/yarn/pull/7330) - [**Francis Crick**](https://guthub.com/fcrick)
+
 - Yarn will tolerate Yaml at parse time. Full support isn't ready yet and will only come at the next major.
 
   [#7300](https://github.com/yarnpkg/yarn/pull/7300) - [**Maël Nison**](https://twitter.com/arcanis)

__tests__/fixtures/index/run-global-add-offline/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "test_global_add_offline",
+  "version": "1.0.0",
+  "license": "UNLICENSED"
+}

__tests__/index.js

@@ -146,6 +146,21 @@ if (semver.satisfies(ver, '>=5.0.0')) {
   });
 }
 
+test.concurrent('should fail to find non-existent package offline', async () => {
+  const command = execCommand(
+    '--offline',
+    ['global', 'add', 'doesnotexistqwertyuiop@2.0.0-doesnotexist', '--global-folder', './global'],
+    'run-global-add-offline',
+    true,
+  );
+  await expectAnErrorMessage(
+    command,
+    `error Couldn't find any versions for "doesnotexistqwertyuiop" that matches "2.0.0-doesnotexist" in our cache ` +
+      '(possible versions are ""). This is usually caused by a missing entry in the lockfile, running Yarn without ' +
+      'the --offline flag may help fix this issue.',
+  );
+});
+
 test.concurrent('should run custom script', async () => {
   const stdout = await execCommand('run', ['custom-script'], 'run-custom-script');
   expectRunOutput(stdout);

src/cli/commands/global.js

@@ -48,6 +48,7 @@ async function updateCwd(config: Config): Promise<void> {
 
   await config.init({
     cwd: config.globalFolder,
+    offline: config.offline,
     binLinks: true,
     globalFolder: config.globalFolder,
     cacheFolder: config._cacheRootFolder,