First cut at beforeExec

index.js

@@ -998,7 +998,7 @@ class Command extends EventEmitter {
    */
 
   hook(event, listener) {
-    const allowedValues = ['beforeAction', 'afterAction'];
+    const allowedValues = ['beforeAction', 'afterAction', 'beforeExec'];
     if (!allowedValues.includes(event)) {
       throw new Error(`Unexpected value for event passed to hook : '${event}'.
 Expecting one of '${allowedValues.join("', '")}'`);
@@ -1606,10 +1606,14 @@ Expecting one of '${allowedValues.join("', '")}'`);
     if (!subCommand) this.help({ error: true });
 
     if (subCommand._executableHandler) {
-      this._executeSubCommand(subCommand, operands.concat(unknown));
-    } else {
-      return subCommand._parseCommand(operands, unknown);
-    }
+      let execResult;
+      execResult = this._chainOrCallHooks(execResult, 'beforeExec');
+      execResult = this._chainOrCall(execResult, () => this._executeSubCommand(subCommand, operands.concat(unknown)));
+      // 'afterExec' is tricky with subcommand close triggering exit
+      return execResult;
+    };
+
+    return subCommand._parseCommand(operands, unknown);
   };
 
   /**