Add tests around cli. Only show usage if on TTY & no argument, allow …

…eaccess error if file not readable.

cli.js

@@ -6,14 +6,14 @@ const readline = require('readline')
 
 const flat = require('./index')
 
-if (process.stdin.isTTY) {
-  const filepath = process.argv.slice(2)[0]
-  if (!filepath) return usage()
+const filepath = process.argv.slice(2)[0]
+if (filepath) {
   // Read from file
   const file = path.resolve(process.cwd(), filepath)
-  if (!file) return usage(1)
-  if (!fs.existsSync(file)) return usage(1)
+  fs.accessSync(file, fs.constants.R_OK) // allow to throw if not readable
   out(require(file))
+} else if (process.stdin.isTTY) {
+  usage(0)
 } else {
   // Read from newline-delimited STDIN
   const lines = []

package.json

@@ -4,7 +4,7 @@
   "main": "index.js",
   "bin": "cli.js",
   "scripts": {
-    "test": "mocha -u tdd --reporter spec && standard index.js test/index.js"
+    "test": "mocha -u tdd --reporter spec && standard cli.js index.js test/index.js"
   },
   "license": "BSD-3-Clause",
   "description": "Take a nested Javascript object and flatten it, or unflatten an object with delimited keys",

test/test.js

@@ -2,6 +2,8 @@
 
 const assert = require('assert')
 const path = require('path')
+const { exec } = require('child_process')
+const pkg = require('../package.json')
 const flat = require('../index')
 
 const flatten = flat.flatten
@@ -593,3 +595,35 @@ suite('Order of Keys', function () {
     assert.deepStrictEqual(Object.keys(obj.abc.c[0]), Object.keys(result.abc.c[0]))
   })
 })
+
+suite('CLI', function () {
+  test('can take filename', function (done) {
+    const cli = path.resolve(__dirname, '..', pkg.bin)
+    const pkgJSON = path.resolve(__dirname, '..', 'package.json')
+    exec(`${cli} ${pkgJSON}`, (err, stdout, stderr) => {
+      assert.ifError(err)
+      assert.strictEqual(stdout.trim(), JSON.stringify(flatten(pkg), null, 2))
+      done()
+    })
+  })
+
+  test('exits with usage if no file', function (done) {
+    const cli = path.resolve(__dirname, '..', pkg.bin)
+    const pkgJSON = path.resolve(__dirname, '..', 'package.json')
+    exec(`${cli} ${pkgJSON}`, (err, stdout, stderr) => {
+      assert.ifError(err)
+      assert.strictEqual(stdout.trim(), JSON.stringify(flatten(pkg), null, 2))
+      done()
+    })
+  })
+
+  test('can take piped file', function (done) {
+    const cli = path.resolve(__dirname, '..', pkg.bin)
+    const pkgJSON = path.resolve(__dirname, '..', 'package.json')
+    exec(`cat ${pkgJSON} | ${cli}`, (err, stdout, stderr) => {
+      assert.ifError(err)
+      assert.strictEqual(stdout.trim(), JSON.stringify(flatten(pkg), null, 2))
+      done()
+    })
+  })
+})