From 5c79e60238955b1c9d14d22d8fcd51cd8bec1c39 Mon Sep 17 00:00:00 2001
From: Arthur Joppart <38424924+BelgianNoise@users.noreply.github.com>
Date: Mon, 5 Dec 2022 13:36:54 +0100
Subject: [PATCH] feat: return clear error when multiple values for a cli flag
 are given

* feat: return clear error when multiple values for a cli flag are given

* chore: change function signature

* test: add testcase for array type yargs parameter
---
 src/init/cli/YargsCliExtractor.ts            | 12 ++++++++++++
 test/unit/init/cli/YargsCliExtractor.test.ts | 16 ++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/init/cli/YargsCliExtractor.ts b/src/init/cli/YargsCliExtractor.ts
index 26ee5f701..7d9c1922e 100644
--- a/src/init/cli/YargsCliExtractor.ts
+++ b/src/init/cli/YargsCliExtractor.ts
@@ -71,6 +71,18 @@ export class YargsCliExtractor extends CliExtractor {
    */
   private createYArgv(argv: readonly string[]): Argv {
     let yArgv = yargs(argv.slice(2));
+
+    // Error and show help message when multiple values were provided
+    // for a non Array type parameter
+    yArgv.check((args): boolean => {
+      for (const [ name, options ] of Object.entries(this.yargsArgOptions)) {
+        if (options.type !== 'array' && Array.isArray(args[name])) {
+          throw new Error(`Multiple values for --${name} (-${options.alias}) were provided where only one is allowed`);
+        }
+      }
+      return true;
+    });
+
     if (this.yargvOptions.usage !== undefined) {
       yArgv = yArgv.usage(this.yargvOptions.usage);
     }
diff --git a/test/unit/init/cli/YargsCliExtractor.test.ts b/test/unit/init/cli/YargsCliExtractor.test.ts
index 7bcc3a39c..93a8ef791 100644
--- a/test/unit/init/cli/YargsCliExtractor.test.ts
+++ b/test/unit/init/cli/YargsCliExtractor.test.ts
@@ -8,6 +8,7 @@ describe('A YargsCliExtractor', (): void => {
   const parameters: YargsParameter[] = [
     new YargsParameter('baseUrl', { alias: 'b', requiresArg: true, type: 'string' }),
     new YargsParameter('port', { alias: 'p', requiresArg: true, type: 'number' }),
+    new YargsParameter('config', { alias: 'c', requiresArg: false, type: 'array' }),
   ];
   let extractor: YargsCliExtractor;
 
@@ -52,6 +53,21 @@ describe('A YargsCliExtractor', (): void => {
     expect(error).toHaveBeenCalledWith('Unknown argument: unsupported');
   });
 
+  it('can error when multiple values are provided for a non array type parameter.', async(): Promise<void> => {
+    extractor = new YargsCliExtractor(parameters, { strictMode: true });
+    const argv = [ 'node', 'script', '-p', '3000', '-b', 'http://localhost:3000/', '-p', '3001' ];
+    await extractor.handle(argv);
+    expect(exit).toHaveBeenCalledTimes(1);
+    expect(error).toHaveBeenCalledWith('Multiple values for --port (-p) were provided where only one is allowed');
+  });
+
+  it('accepts multiple values for array type parameters.', async(): Promise<void> => {
+    const argv = [ 'node', 'script', '-c', './config/a.json', '-c', './config/b.json', '-b', 'http://localhost:3000/', '-p', '3000' ];
+    await expect(extractor.handle(argv)).resolves.toEqual(expect.objectContaining({
+      config: [ './config/a.json', './config/b.json' ],
+    }));
+  });
+
   it('can parse environment variables.', async(): Promise<void> => {
     // While the code below does go into the corresponding values,
     // yargs does not see the new environment variable for some reason.