fix: support single dash as positional (#49)

README.md

@@ -201,7 +201,7 @@ const { flags, values, positionals } = parseArgs(argv, options);
   - the first flag would be parsed as `'-foo'`
   - the second flag would be parsed as `'foo'`
 - Is `-` a positional? ie, `bash some-test.sh | tap -`
-  - no
+  - yes
 
 [coverage-image]: https://img.shields.io/nycrc/pkgjs/parseargs
 [coverage-url]: https://github.com/pkgjs/parseargs/blob/main/.nycrc

index.js

@@ -105,9 +105,14 @@ const parseArgs = (
     let arg = argv[pos];
 
     if (StringPrototypeStartsWith(arg, '-')) {
-      // Everything after a bare '--' is considered a positional argument
-      // and is returned verbatim
-      if (arg === '--') {
+      if (arg === '-') {
+        // '-' commonly used to represent stdin/stdout, treat as positional
+        result.positionals = ArrayPrototypeConcat(result.positionals, '-');
+        ++pos;
+        continue;
+      } else if (arg === '--') {
+        // Everything after a bare '--' is considered a positional argument
+        // and is returned verbatim
         result.positionals = ArrayPrototypeConcat(
           result.positionals,
           ArrayPrototypeSlice(argv, ++pos)

test/index.js

@@ -111,6 +111,16 @@ test('args equals are passed "withValue"', function(t) {
   t.end();
 });
 
+test('when args include single dash then result stores dash as positional', function(t) {
+  const passedArgs = ['-'];
+  const expected = { flags: { }, values: { }, positionals: ['-'] };
+  const args = parseArgs(passedArgs);
+
+  t.deepEqual(args, expected);
+
+  t.end();
+});
+
 test('zero config args equals are parsed as if "withValue"', function(t) {
   const passedArgs = ['--so=wat'];
   const passedOptions = { };