chore: add CLI-level validation for template-path parameter

Author: rohang9000

packages/@aws-cdk/user-input-gen/lib/yargs-gen.ts

@@ -105,17 +105,22 @@ function makeYargs(config: CliConfig, helpers: CliHelpers): Statement {
     }
     commandCallArgs.push(lit(commandFacts.description));
 
-    if (commandFacts.options) {
-      commandCallArgs.push(optionsExpr);
-    }
-
     // Add implies calls if present
     if (commandFacts.implies) {
       for (const [key, value] of Object.entries(commandFacts.implies)) {
         optionsExpr = optionsExpr.callMethod('implies', lit(key), lit(value));
       }
     }
 
+    // Add check function if present
+    if (commandFacts.check) {
+      optionsExpr = optionsExpr.callMethod('check', code.expr.directCode(commandFacts.check.toString()));
+    }
+
+    if (commandFacts.options || commandFacts.check) {
+      commandCallArgs.push(optionsExpr);
+    }
+
     yargsExpr = yargsExpr.callMethod('command', ...commandCallArgs);
   }
 

packages/@aws-cdk/user-input-gen/lib/yargs-types.ts

@@ -8,7 +8,7 @@ interface YargsCommand {
 export interface CliAction extends YargsCommand {
   options?: { [optionName: string]: CliOption };
   implies?: { [key: string]: string };
-  // check?: string;
+  check?: (argv: any) => boolean | Promise<boolean>;
 }
 
 interface YargsArg {

packages/aws-cdk/lib/cli/cli-config.ts

@@ -405,7 +405,14 @@ export async function makeConfig(): Promise<CliConfig> {
           'from-git-url': { type: 'string', desc: 'Git repository URL to clone custom template from', requiresArg: true, conflicts: ['lib-version', 'from-path'] },
           'template-path': { type: 'string', desc: 'Path to a specific template within a multi-template repository', requiresArg: true },
         },
-
+        check: (argv: any) => {
+          if (argv['template-path'] && !argv['from-path'] && !argv['from-git-url']) {
+            const error = new Error('--template-path can only be used with --from-path or --from-git-url');
+            error.name = 'ValidationError';
+            throw error;
+          }
+          return true;
+        },
       },
       'migrate': {
         description: 'Migrate existing AWS resources into a CDK app',

packages/aws-cdk/lib/commands/init/init.ts

@@ -91,11 +91,6 @@ export async function cliInit(options: CliInitOptions) {
   const generateOnly = options.generateOnly ?? false;
   const workDir = options.workDir ?? process.cwd();
 
-  // Validate that if template-path is provided, exactly one custom template source must be provided
-  if (options.templatePath && !options.fromPath && !options.fromGitUrl) {
-    throw new ToolkitError('--template-path can only be used with --from-path or --from-git-url');
-  }
-
   // Show available templates if no type and no language provided (main branch logic)
   if (!options.fromPath && !options.fromGitUrl && !options.type && !options.language) {
     await printAvailableTemplates(ioHelper);

packages/aws-cdk/test/commands/init.test.ts

@@ -607,18 +607,24 @@ describe('constructs version', () => {
   });
 
   cliTest('template-path validation requires from-path or from-git-url', async (workDir) => {
-    const projectDir = path.join(workDir, 'my-project');
-    await fs.mkdirp(projectDir);
+    const { exec } = await import('child_process');
+    const { promisify } = await import('util');
+    const execAsync = promisify(exec);
+    const cdkBin = path.join(__dirname, '..', '..', 'bin', 'cdk');
+
+    const emptyDir = path.join(workDir, 'empty-project');
+    await fs.mkdirp(emptyDir);
 
     // Test that template-path fails when used without from-path or from-git-url
-    await expect(cliInit({
-      ioHelper,
-      templatePath: 'some-template',
-      language: 'typescript',
-      canUseNetwork: false,
-      generateOnly: true,
-      workDir: projectDir,
-    })).rejects.toThrow('--template-path can only be used with --from-path or --from-git-url');
+    try {
+      await execAsync(`node ${cdkBin} init --template-path some-template --language typescript --generate-only`, {
+        cwd: emptyDir,
+        env: { ...process.env, CDK_DISABLE_VERSION_CHECK: '1' },
+      });
+      throw new Error('Expected command to fail but it succeeded');
+    } catch (error: any) {
+      expect(error.stderr || error.message).toContain('--template-path can only be used with --from-path or --from-git-url');
+    }
   });
 
   cliTest('hook files are ignored during template copy', async (workDir) => {