feat: add default cli flag

PR-URL: #534
Credit: @nohehf
Close: #534
Reviewed-by: @isaacs

src/bin.ts

@@ -2,11 +2,11 @@
 import { foregroundChild } from 'foreground-child'
 import { existsSync } from 'fs'
 import { jack } from 'jackspeak'
-import { globStream } from './index.js'
 import { version } from '../package.json'
+import { globStream } from './index.js'
 
 const j = jack({
-  usage: 'glob [options] [<pattern> [<pattern> ...]]'
+  usage: 'glob [options] [<pattern> [<pattern> ...]]',
 })
   .description(
     `
@@ -24,6 +24,14 @@ const j = jack({
                     matches as arguments.`,
     },
   })
+  .opt({
+    default: {
+      short: 'p',
+      hint: 'pattern',
+      description: `If no positional arguments are provided, glob will use
+                    this pattern`,
+    },
+  })
   .flag({
     all: {
       short: 'A',
@@ -219,7 +227,10 @@ try {
     console.log(j.usage())
     process.exit(0)
   }
-  if (positionals.length === 0) throw 'No patterns provided'
+  if (positionals.length === 0 && !values.default)
+    throw 'No patterns provided'
+  if (positionals.length === 0 && values.default)
+    positionals.push(values.default)
   const patterns = values.all
     ? positionals
     : positionals.filter(p => !existsSync(p))

test/bin.ts

@@ -82,3 +82,24 @@ t.test('prioritizes exact match if exists, unless --all', async t => {
   t.match(all.stdout, 'routes/i.tsx\n')
   t.match(all.stdout, 'routes/d.tsx\n')
 })
+
+t.test('uses default pattern if none provided', async t => {
+  const cwd = t.testdir({
+    a: {
+      'x.y': '',
+      'x.a': '',
+      b: {
+        'z.y': '',
+        'z.a': '',
+      },
+    },
+  })
+
+  const def = await run(['-p', '**/*.y'], { cwd })
+  t.match(def.stdout, `a${sep}x.y\n`)
+  t.match(def.stdout, `a${sep}b${sep}z.y\n`)
+
+  const exp = await run(['-p', '**/*.y', '**/*.a'], { cwd })
+  t.match(exp.stdout, `a${sep}x.a\n`)
+  t.match(exp.stdout, `a${sep}b${sep}z.a\n`)
+})