feat(@angular/cli): add support for auto completion

packages/angular/cli/src/command-builder/architect-base-command-module.ts

@@ -7,7 +7,10 @@
  */
 
 import { Architect, Target } from '@angular-devkit/architect';
-import { WorkspaceNodeModulesArchitectHost } from '@angular-devkit/architect/node';
+import {
+  NodeModulesBuilderInfo,
+  WorkspaceNodeModulesArchitectHost,
+} from '@angular-devkit/architect/node';
 import { json } from '@angular-devkit/core';
 import { spawnSync } from 'child_process';
 import { existsSync } from 'fs';
@@ -100,9 +103,15 @@ export abstract class ArchitectBaseCommandModule<T>
 
   protected async getArchitectTargetOptions(target: Target): Promise<Option[]> {
     const architectHost = this.getArchitectHost();
-    const builderConf = await architectHost.getBuilderNameForTarget(target);
+    let builderConf: string;
+
+    try {
+      builderConf = await architectHost.getBuilderNameForTarget(target);
+    } catch {
+      return [];
+    }
 
-    let builderDesc;
+    let builderDesc: NodeModulesBuilderInfo;
     try {
       builderDesc = await architectHost.resolveBuilder(builderConf);
     } catch (e) {

packages/angular/cli/src/command-builder/architect-command-module.ts

@@ -29,10 +29,15 @@ export abstract class ArchitectCommandModule
   abstract readonly multiTarget: boolean;
 
   async builder(argv: Argv): Promise<Argv<ArchitectCommandArgs>> {
+    const project = this.getArchitectProject();
+    const { jsonHelp, getYargsCompletions, help } = this.context.args.options;
+
     const localYargs: Argv<ArchitectCommandArgs> = argv
       .positional('project', {
         describe: 'The name of the project to build. Can be an application or a library.',
         type: 'string',
+        // Hide choices from JSON help so that we don't display them in AIO.
+        choices: jsonHelp ? undefined : this.getProjectChoices(),
       })
       .option('configuration', {
         describe:
@@ -42,10 +47,15 @@ export abstract class ArchitectCommandModule
           `For more information, see https://angular.io/guide/workspace-config#alternate-build-configurations.`,
         alias: 'c',
         type: 'string',
+        // Show only in when using --help and auto completion because otherwise comma seperated configuration values will be invalid.
+        // Also, hide choices from JSON help so that we don't display them in AIO.
+        choices:
+          (getYargsCompletions || help) && !jsonHelp && project
+            ? this.getConfigurationChoices(project)
+            : undefined,
       })
       .strict();
 
-    const project = this.getArchitectProject();
     if (!project) {
       return localYargs;
     }
@@ -92,11 +102,7 @@ export abstract class ArchitectCommandModule
     const [, projectName] = this.context.args.positional;
 
     if (projectName) {
-      if (!workspace.projects.has(projectName)) {
-        throw new CommandModuleError(`Project '${projectName}' does not exist.`);
-      }
-
-      return projectName;
+      return workspace.projects.has(projectName) ? projectName : undefined;
     }
 
     const target = this.getArchitectTarget();
@@ -136,4 +142,24 @@ export abstract class ArchitectCommandModule
 
     return undefined;
   }
+
+  /** @returns a sorted list of project names to be used for auto completion. */
+  private getProjectChoices(): string[] | undefined {
+    const { workspace } = this.context;
+
+    return workspace ? [...workspace.projects.keys()].sort() : undefined;
+  }
+
+  /** @returns a sorted list of configuration names to be used for auto completion. */
+  private getConfigurationChoices(project: string): string[] | undefined {
+    const projectDefinition = this.context.workspace?.projects.get(project);
+    if (!projectDefinition) {
+      return undefined;
+    }
+
+    const target = this.getArchitectTarget();
+    const configurations = projectDefinition.targets.get(target)?.configurations;
+
+    return configurations ? Object.keys(configurations).sort() : undefined;
+  }
 }

packages/angular/cli/src/command-builder/command-module.ts

@@ -48,6 +48,7 @@ export interface CommandContext {
     options: {
       help: boolean;
       jsonHelp: boolean;
+      getYargsCompletions: boolean;
     } & Record<string, unknown>;
   };
 }

packages/angular/cli/src/command-builder/command-runner.ts

@@ -13,6 +13,7 @@ import { AddCommandModule } from '../commands/add/cli';
 import { AnalyticsCommandModule } from '../commands/analytics/cli';
 import { BuildCommandModule } from '../commands/build/cli';
 import { CacheCommandModule } from '../commands/cache/cli';
+import { CompletionCommandModule } from '../commands/completion/cli';
 import { ConfigCommandModule } from '../commands/config/cli';
 import { DeployCommandModule } from '../commands/deploy/cli';
 import { DocCommandModule } from '../commands/doc/cli';
@@ -54,18 +55,26 @@ const COMMANDS = [
   UpdateCommandModule,
   RunCommandModule,
   CacheCommandModule,
+  CompletionCommandModule,
 ].sort(); // Will be sorted by class name.
 
 const yargsParser = Parser as unknown as typeof Parser.default;
 
 export async function runCommand(args: string[], logger: logging.Logger): Promise<number> {
   const {
     $0,
-    _: positional,
+    _,
     help = false,
     jsonHelp = false,
+    getYargsCompletions = false,
     ...rest
-  } = yargsParser(args, { boolean: ['help', 'json-help'], alias: { 'collection': 'c' } });
+  } = yargsParser(args, {
+    boolean: ['help', 'json-help', 'get-yargs-completions'],
+    alias: { 'collection': 'c' },
+  });
+
+  // When `getYargsCompletions` is true the scriptName 'ng' at index 0 is not removed.
+  const positional = getYargsCompletions ? _.slice(1) : _;
 
   let workspace: AngularWorkspace | undefined;
   let globalConfiguration: AngularWorkspace | undefined;
@@ -93,6 +102,7 @@ export async function runCommand(args: string[], logger: logging.Logger): Promis
       options: {
         help,
         jsonHelp,
+        getYargsCompletions,
         ...rest,
       },
     },
@@ -111,9 +121,16 @@ export async function runCommand(args: string[], logger: logging.Logger): Promis
     localYargs = addCommandModuleToYargs(localYargs, CommandModule, context);
   }
 
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const usageInstance = (localYargs as any).getInternalMethods().getUsageInstance();
   if (jsonHelp) {
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    (localYargs as any).getInternalMethods().getUsageInstance().help = () => jsonHelpUsage();
+    usageInstance.help = () => jsonHelpUsage();
+  }
+
+  if (getYargsCompletions) {
+    // When in auto completion mode avoid printing description as it causes a slugish
+    // experience when there are a large set of options.
+    usageInstance.getDescriptions = () => ({});
   }
 
   await localYargs

packages/angular/cli/src/commands/completion/cli.ts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import { join } from 'path';
+import yargs, { Argv } from 'yargs';
+import { CommandModule, CommandModuleImplementation } from '../../command-builder/command-module';
+
+export class CompletionCommandModule extends CommandModule implements CommandModuleImplementation {
+  command = 'completion';
+  describe = 'Generate a bash and zsh real-time type-ahead autocompletion script.';
+  longDescriptionPath = join(__dirname, 'long-description.md');
+
+  builder(localYargs: Argv): Argv {
+    return localYargs;
+  }
+
+  run(): void {
+    yargs.showCompletionScript();
+  }
+}

packages/angular/cli/src/commands/completion/long-description.md

@@ -0,0 +1 @@
+To enable bash and zsh real-time type-ahead autocompletion, copy and paste the generated script to your `.bashrc`, `.bash_profile`, `.zshrc` or `.zsh_profile`.

packages/angular/cli/src/commands/run/cli.ts

@@ -11,7 +11,6 @@ import { join } from 'path';
 import { Argv } from 'yargs';
 import { ArchitectBaseCommandModule } from '../../command-builder/architect-base-command-module';
 import {
-  CommandModule,
   CommandModuleError,
   CommandModuleImplementation,
   CommandScope,
@@ -35,11 +34,16 @@ export class RunCommandModule
   longDescriptionPath = join(__dirname, 'long-description.md');
 
   async builder(argv: Argv): Promise<Argv<RunCommandArgs>> {
+    const { jsonHelp, getYargsCompletions, help } = this.context.args.options;
+
     const localYargs: Argv<RunCommandArgs> = argv
       .positional('target', {
         describe: 'The Architect target to run.',
         type: 'string',
         demandOption: true,
+        // Show only in when using --help and auto completion because otherwise comma seperated configuration values will be invalid.
+        // Also, hide choices from JSON help so that we don't display them in AIO.
+        choices: (getYargsCompletions || help) && !jsonHelp ? this.getTargetChoices() : undefined,
       })
       .strict();
 
@@ -78,4 +82,29 @@ export class RunCommandModule
       configuration,
     };
   }
+
+  /** @returns a sorted list of target specifiers to be used for auto completion. */
+  private getTargetChoices(): string[] | undefined {
+    if (!this.context.workspace) {
+      return;
+    }
+
+    const targets = [];
+    for (const [projectName, project] of this.context.workspace.projects) {
+      for (const [targetName, target] of project.targets) {
+        const currentTarget = `${projectName}:${targetName}`;
+        targets.push(currentTarget);
+
+        if (!target.configurations) {
+          continue;
+        }
+
+        for (const configName of Object.keys(target.configurations)) {
+          targets.push(`${currentTarget}:${configName}`);
+        }
+      }
+    }
+
+    return targets.sort();
+  }
 }

tests/legacy-cli/e2e/tests/misc/browsers.ts

@@ -1,7 +1,7 @@
 import express from 'express';
 import * as path from 'path';
 import { copyProjectAsset } from '../../utils/assets';
-import { appendToFile, replaceInFile } from '../../utils/fs';
+import { replaceInFile } from '../../utils/fs';
 import { ng } from '../../utils/process';
 
 export default async function () {

tests/legacy-cli/e2e/tests/misc/completion.ts

@@ -0,0 +1,51 @@
+import { execAndWaitForOutputToMatch } from '../../utils/process';
+
+export default async function () {
+  // ng build
+  await execAndWaitForOutputToMatch('ng', ['--get-yargs-completions', 'b', ''], /test-project/);
+  await execAndWaitForOutputToMatch('ng', ['--get-yargs-completions', 'build', ''], /test-project/);
+  await execAndWaitForOutputToMatch('ng', ['--get-yargs-completions', 'build', '--a'], /--aot/);
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'build', '--configuration'],
+    /production/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'b', '--configuration'],
+    /production/,
+  );
+
+  // ng run
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', ''],
+    /test-project\:build\:development/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', ''],
+    /test-project\:build/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', ''],
+    /test-project\:test/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', 'test-project:build'],
+    /test-project\:build\:development/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', 'test-project:'],
+    /test-project\:test/,
+  );
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['--get-yargs-completions', 'run', 'test-project:build'],
+    // does not include 'test-project:serve'
+    /^((?!:serve).)*$/,
+  );
+}