fix: show deprecation warning in help when using deprecated alias

src/help/index.ts

@@ -161,11 +161,17 @@ export class Help extends HelpBase {
     if (state) {
       this.log(
         state === 'deprecated'
-          ? `${formatCommandDeprecationWarning(toConfiguredId(name, this.config), command.deprecationOptions)}`
+          ? `${formatCommandDeprecationWarning(toConfiguredId(name, this.config), command.deprecationOptions)}\n`
           : `This command is in ${state}.\n`,
       )
     }
 
+    if (command.deprecateAliases && command.aliases.includes(name)) {
+      const actualCmd = this.config.commands.find((c) => c.aliases.includes(name))
+      const opts = {...command.deprecationOptions, ...(actualCmd ? {to: actualCmd.id} : {})}
+      this.log(`${formatCommandDeprecationWarning(toConfiguredId(name, this.config), opts)}\n`)
+    }
+
     const summary = this.summary(command)
     if (summary) {
       this.log(summary + '\n')

test/help/fixtures/fixtures.ts

@@ -126,3 +126,20 @@ export const DbTopic: Topic = {
   name: 'db',
   description: 'This topic is for the db topic',
 }
+
+// deprecateAliases
+export class DeprecateAliases extends Command {
+  static id = 'foo:bar'
+
+  static aliases = ['foo:bar:alias']
+
+  static deprecateAliases = true
+
+  static flags = {}
+
+  static args = {}
+
+  async run(): Promise<void> {
+    'run'
+  }
+}

test/help/show-help.test.ts

@@ -13,6 +13,7 @@ import {
   AppsTopic,
   DbCreate,
   DbTopic,
+  DeprecateAliases,
 } from './fixtures/fixtures'
 import {Config, Interfaces} from '../../src'
 import {monkeyPatchCommands} from './help-test-utils'
@@ -257,6 +258,32 @@ COMMANDS
   apps:create   Create an app
   apps:destroy  Destroy an app`)
     })
+
+  test
+    .loadConfig()
+    .stdout()
+    .do(async (ctx) => {
+      const {config} = ctx
+      monkeyPatchCommands(config, [
+        {
+          name: 'plugin-1',
+          commands: [DeprecateAliases],
+          topics: [],
+        },
+      ])
+
+      const help = new TestHelp(config as any)
+      await help.showHelp(['foo:bar:alias'])
+    })
+    .it('show deprecation warning when using alias', ({stdout}) => {
+      expect(stdout.trim()).to.equal(`The "foo:bar:alias" command has been deprecated. Use "foo:bar" instead.
+
+USAGE
+  $ oclif foo:bar:alias
+
+ALIASES
+  $ oclif foo:bar:alias`)
+    })
 })
 
 describe('showHelp for a command', () => {