Add support for intercepting the command line interface with the command:before hook

Author: kraih

CHANGELOG.md

@@ -1,6 +1,12 @@
 
 # Changelog
 
+## v1.2.0 (2022-07-02)
+
+### Features
+
+  * Added support for intercepting the command line interface with the `command:before` hook.
+
 ## v1.1.2 (2022-06-30)
 
 ### Bug Fixes

docs/Cheatsheet.md

@@ -584,7 +584,7 @@ app.addAppHook('command:before', async (app, args) => {
 ```
 
 Useful for reconfiguring the application before running a command or to modify the behavior of a command. Passed the
-application object and command arguments.
+application object and command arguments. Can return `true` to intercept the command line interface.
 
 ### server:start
 

src/cli.ts

@@ -61,7 +61,7 @@ export class CLI {
 
     const app = this._app.deref();
     if (app === undefined) return;
-    await app.hooks.commandBefore(app, commandArgs);
+    if ((await app.hooks.commandBefore(app, commandArgs)) === true) return;
 
     const parsed = nopt({help: Boolean}, {h: '--help'}, commandArgs);
     const argv = parsed.argv;

src/hooks.ts

@@ -20,9 +20,10 @@ export class Hooks {
    * Run `command:start` hook with dependencies. Note that this method is EXPERIMENTAL and might change without
    * warning!
    */
-  async commandBefore(app: MojoApp, commandArgs: string[]): Promise<void> {
-    await this.runHook('command:before', app, commandArgs);
+  async commandBefore(app: MojoApp, commandArgs: string[]): Promise<any> {
+    const result = await this.runHook('command:before', app, commandArgs);
     await this._appStart(app);
+    return result;
   }
 
   /**

test/command-app.js

@@ -54,6 +54,13 @@ t.test('Command app', async t => {
         'Hello Mojo!' +
         'server:stop: developmentcommand:after: developmentapp:stop: development'
     );
+
+    process.env.MOJO_COMMAND_TEST = '1';
+    const output2 = await captureOutput(async () => {
+      await app.cli.start();
+    });
+    t.match(output2.toString(), 'command:before: skip cliapp:start: development');
+    delete process.env.MOJO_COMMAND_TEST;
   });
 
   await t.test('Custom command', async t => {
@@ -98,7 +105,7 @@ t.test('Command app', async t => {
     const output2 = await captureOutput(async () => {
       await app.cli.start('eval', 'await 100 + 924');
     });
-    t.equal(output2.toString(), 'app:start: developmentapp:stop: development');
+    t.equal(output2.toString(), '');
 
     const output3 = await captureOutput(async () => {
       await app.cli.start('eval', '-v', 'await 100 + 924');

test/support/js/command-app/index.js

@@ -12,6 +12,13 @@ app.addAppHook('command:before', (app, args) => {
   }
 });
 
+app.addAppHook('command:before', async () => {
+  if (process.env.MOJO_COMMAND_TEST !== undefined) {
+    process.stdout.write(Buffer.from(`command:before: skip cli`));
+    return true;
+  }
+});
+
 app.addAppHook('app:start', app => {
   const mode = app.mode;
   process.stdout.write(Buffer.from(`app:start: ${mode}`));