From ee631fe30b5d5c57e8fd8472c0c583fd6d942279 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 8 Feb 2020 13:53:38 +1300
Subject: [PATCH 1/2] Suggest help when unknown command

---
 index.js                           | 7 ++++++-
 tests/command.exitOverride.test.js | 3 ++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index 9dc4aa8a1..bd8a834ad 100644
--- a/index.js
+++ b/index.js
@@ -1124,7 +1124,12 @@ class Command extends EventEmitter {
    */
 
   unknownCommand() {
-    const message = `error: unknown command '${this.args[0]}'`;
+    const partCommands = [this.name()];
+    for (let parentCmd = this.parent; parentCmd; parentCmd = parentCmd.parent) {
+      partCommands.unshift(parentCmd.name());
+    }
+    const fullCommand = partCommands.join(' ');
+    const message = `error: unknown command '${this.args[0]}'. See '${fullCommand} --help'.`;
     console.error(message);
     this._exit(1, 'commander.unknownCommand', message);
   };
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index fb76504bb..52917ca38 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -54,6 +54,7 @@ describe('.exitOverride and error details', () => {
   test('when specify unknown command then throw CommanderError', () => {
     const program = new commander.Command();
     program
+      .name('prog')
       .exitOverride()
       .command('sub');
 
@@ -65,7 +66,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unknown command 'oops'");
+    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unknown command 'oops'. See 'prog --help'.");
   });
 
   // Same error as above, but with custom handler.

From 225ab71089fe5f72ba44a840801ac11d8117be19 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 8 Feb 2020 14:05:09 +1300
Subject: [PATCH 2/2] Use custom help flag in message

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index bd8a834ad..b869cb640 100644
--- a/index.js
+++ b/index.js
@@ -1129,7 +1129,7 @@ class Command extends EventEmitter {
       partCommands.unshift(parentCmd.name());
     }
     const fullCommand = partCommands.join(' ');
-    const message = `error: unknown command '${this.args[0]}'. See '${fullCommand} --help'.`;
+    const message = `error: unknown command '${this.args[0]}'. See '${fullCommand} ${this._helpLongFlag}'.`;
     console.error(message);
     this._exit(1, 'commander.unknownCommand', message);
   };