fix option type definition to match usage.

tests/options.custom-processing.test.js

@@ -13,6 +13,10 @@ function collect(value, previous) {
   return previous.concat([value]);
 }
 
+function collectVoid(value, previous) {
+  previous.concat([value]);
+}
+
 function commaSeparatedList(value, dummyPrevious) {
   return value.split(',');
 }
@@ -131,6 +135,22 @@ test('when collect -c a -c b -c c then value is [a, b, c]', () => {
   program.parse(['node', 'test', '-c', 'a', '-c', 'b', '-c', 'c']);
   expect(program.collect).toEqual(['a', 'b', 'c']);
 });
+// freeze void returning collector behaviour
+test('when collect returning Void -c a -c b -c c then value is void', () => {
+  const program = new commander.Command();
+  program
+    .option('-c, --collect <value>', 'repeatable value', collectVoid, []);
+  program.parse(['node', 'test', '-c', 'a', '-c', 'b', '-c', 'c']);
+  expect(program.collect).toBeUndefined();
+});
+// freeze void returning collector behaviour
+test('when collect returning Void -c a -c b -c c -c d then value is []', () => {
+  const program = new commander.Command();
+  program
+    .option('-c, --collect <value>', 'repeatable value', collectVoid, []);
+  program.parse(['node', 'test', '-c', 'a', '-c', 'b', '-c', 'c', '-c', 'd']);
+  expect(program.collect).toEqual([]);
+});
 
 test('when commaSeparatedList x,y,z then value is [x, y, z]', () => {
   const program = new commander.Command();

typings/commander-tests.ts

@@ -37,6 +37,12 @@ function collect(val: string, memo: string[]) {
     memo.push(val);
     return memo;
 }
+/*
+ * Collector without return all so work
+ */
+//function collect2(val: string, memo: string[]) {
+//    memo.push(val);
+//}
 
 function increaseVerbosity(v: any, total: number) {
     return total + 1;
@@ -51,6 +57,7 @@ program
     .option('-l, --list <items>', 'A list', list)
     .option('-o, --optional [value]', 'An optional value')
     .option('-c, --collect [value]', 'A repeatable value', collect, [])
+    // .option('--collect2 [value]', 'A repeatable value void return', collect2, [])
     .option('-v, --verbose', 'A value that can be increased', increaseVerbosity, 0)
     .parse(process.argv);
 

typings/index.d.ts

@@ -162,24 +162,22 @@ declare namespace commander {
      *
      *     // optional argument
      *     program.option('-c, --cheese [type]', 'add cheese [marble]');
-     *
-     * @param {string} flags
-     * @param {string} [description]
-     * @param {((arg1: any, arg2: any) => void) | RegExp} [fn] function or default
-     * @param {*} [defaultValue]
-     * @returns {Command} for chaining
      */
-    option(flags: string, description?: string, fn?: ((arg1: any, arg2: any) => void) | RegExp, defaultValue?: any): Command;
-    option(flags: string, description?: string, defaultValue?: any): Command;
+    option(flags: string, description: string, regexp: RegExp, defaultValue?: string): Command;
+    // option<T>(flags: string, description: string, fn: (value: string, previous: T) => void, defaultValue: T): Command;
+    option<T>(flags: string, description: string, fn: (value: string, previous: T) => T, defaultValue?: T): Command;
+    option(flags: string, description?: string, defaultValue?: string): Command;
 
     /**
      * Define a required option, which must have a value after parsing. This usually means
      * the option must be specified on the command line. (Otherwise the same as .option().)
      *
      * The `flags` string should contain both the short and long flags, separated by comma, a pipe or space.
      */
-    requiredOption(flags: string, description?: string, fn?: ((arg1: any, arg2: any) => void) | RegExp, defaultValue?: any): Command;
-    requiredOption(flags: string, description?: string, defaultValue?: any): Command;
+    requiredOption(flags: string, description: string, regexp: RegExp, defaultValue?: string): Command;
+    // requiredOption<T>(flags: string, description: string, fn: (value: string, previous: T) => void, defaultValue: T): Command;
+    requiredOption<T>(flags: string, description: string, fn: (value: string, previous: T) => T, defaultValue?: T): Command;
+    requiredOption(flags: string, description?: string, defaultValue?: string): Command;
 
     /**
      * Allow unknown options on the command line.