chore: remove app:diff command from cli

.changeset/unlucky-ducks-report.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+The `yarn backstage-cli app:diff` has been broken since a couple of months. The command to perform updates `yarn backstage-cli versions:bump` prints change logs which seems to be a good replacement for this command.

docs/cli/commands.md

@@ -24,7 +24,6 @@ Below is a cleaned up output of `yarn backstage-cli --help`.
 
 ```text
 app:build                Build an app for a production release
-app:diff                 Diff an existing app with the creation template
 app:serve                Serve an app for local development
 
 backend:build            Build a backend plugin
@@ -112,25 +111,6 @@ Options:
   -h, --help       display help for command
 ```
 
-## app:diff
-
-Scope: `app`
-
-Diff an existing app with the template used in `@backstage/create-app`. This
-will verify that your app package has not diverged from the template, and can be
-useful to run after updating the version of `@backstage/cli` in your app.
-
-This command is experimental and may be removed in the future.
-
-```text
-Usage: backstage-cli app:diff
-
-Options:
-  --check     Fail if changes are required
-  --yes       Apply all changes
-  -h, --help  display help for command
-```
-
 ## app:serve
 
 Scope: `app`

packages/cli/src/commands/app/diff.ts

@@ -1,74 +0,0 @@
-/*
- * Copyright 2020 Spotify AB
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import { Command } from 'commander';
-import {
-  diffTemplateFiles,
-  handlers,
-  handleAllFiles,
-  inquirerPromptFunc,
-  makeCheckPromptFunc,
-  yesPromptFunc,
-} from '../../lib/diff';
-import { version } from '../../lib/version';
-
-const fileHandlers = [
-  {
-    patterns: ['packages/app/package.json'],
-    handler: handlers.appPackageJson,
-  },
-  {
-    patterns: [/tsconfig\.json$/],
-    handler: handlers.exactMatch,
-  },
-  {
-    patterns: [
-      /README\.md$/,
-      /\.eslintrc\.js$/,
-      // make sure files in 1st level of src/ and dev/ exist
-      /^packages\/app\/(src|dev)\/[^/]+$/,
-    ],
-    handler: handlers.exists,
-  },
-  {
-    patterns: [
-      'lerna.json',
-      /^src\//,
-      /^patches\//,
-      /^packages\/app\/public\//,
-      /^packages\/app\/cypress/,
-      // Let plugin:diff take care of the plugins
-      /^plugins/,
-      /package\.json$/,
-    ],
-    handler: handlers.skip,
-  },
-];
-
-export default async (cmd: Command) => {
-  let promptFunc = inquirerPromptFunc;
-  let finalize = () => {};
-
-  if (cmd.check) {
-    [promptFunc, finalize] = makeCheckPromptFunc();
-  } else if (cmd.yes) {
-    promptFunc = yesPromptFunc;
-  }
-
-  const templateFiles = await diffTemplateFiles('default-app', { version });
-  await handleAllFiles(fileHandlers, templateFiles, promptFunc);
-  await finalize();
-};

packages/cli/src/commands/index.ts

@@ -76,13 +76,6 @@ export function registerCommands(program: CommanderStatic) {
     .option(...configOption)
     .action(lazy(() => import('./backend/dev').then(m => m.default)));
 
-  program
-    .command('app:diff')
-    .option('--check', 'Fail if changes are required')
-    .option('--yes', 'Apply all changes')
-    .description('Diff an existing app with the creation template')
-    .action(lazy(() => import('./app/diff').then(m => m.default)));
-
   program
     .command('create-plugin')
     .option(