fix(renderer): force process.stdout to be a TTY to support spinners

bin/lint-staged.js

@@ -4,15 +4,14 @@ import fs from 'node:fs'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
-import { isColorSupported } from 'colorette'
 import { Option, program } from 'commander'
 import debug from 'debug'
 
-import lintStaged from '../lib/index.js'
-import { CONFIG_STDIN_ERROR } from '../lib/messages.js'
+import { forceTty } from '../lib/forceTty.js'
 
-// Force colors for packages that depend on https://www.npmjs.com/package/supports-color
-if (isColorSupported) {
+// Force `process.stdout` to be a TTY to support spinners
+const ttyHandle = await forceTty()
+if (ttyHandle) {
   process.env.FORCE_COLOR = '1'
 }
 
@@ -113,6 +112,8 @@ if (options.configPath === '-') {
   try {
     options.config = fs.readFileSync(process.stdin.fd, 'utf8').toString().trim()
   } catch {
+    // Lazy import so that `colorette` is not loaded before `forceTty`
+    const { CONFIG_STDIN_ERROR } = await import('../lib/messages.js')
     console.error(CONFIG_STDIN_ERROR)
     process.exit(1)
   }
@@ -124,10 +125,12 @@ if (options.configPath === '-') {
   }
 }
 
-lintStaged(options)
-  .then((passed) => {
-    process.exitCode = passed ? 0 : 1
-  })
-  .catch(() => {
-    process.exitCode = 1
-  })
+try {
+  const { default: lintStaged } = await import('../lib/index.js')
+  const passed = await lintStaged(options)
+  process.exitCode = passed ? 0 : 1
+} catch {
+  process.exitCode = 1
+} finally {
+  await ttyHandle?.close()
+}

lib/forceTty.js

@@ -0,0 +1,49 @@
+import { constants } from 'node:fs'
+import fs from 'node:fs/promises'
+import tty from 'node:tty'
+
+const getHandle = async () => {
+  if (process.platform === 'win32') {
+    return await fs.open('conout$', constants.O_WRONLY | constants.O_EXCL, 0o666)
+  } else {
+    return await fs.open('/dev/tty', constants.O_WRONLY + constants.O_NOCTTY)
+  }
+}
+
+/**
+ * Try to override the `process.stdout` with a TTY `tty.WriteStream`.
+ * When invoking lint-staged through Git hooks, the shell might not
+ * be a TTY, but we still want to enable spinners in a "non-hacky" way.
+ *
+ * @returns {Promise<fs.FileHandle | null>} the `FileHandle` pointing to the TTY, or `null` when failed.
+ */
+export const forceTty = async () => {
+  /** No need to do anything if stdout is already a TTY. */
+  if (process.stdout.isTTY) return null
+
+  try {
+    const handle = await getHandle()
+
+    /**
+     * Probably not realistic that the TTY handle is not a TTY,
+     * but close the handle just in case.
+     */
+    if (tty.isatty(handle.fd)) {
+      await handle.close()
+      return null
+    }
+
+    const stdout = new tty.WriteStream(handle.fd)
+
+    /** Override `process.stdout` */
+    Object.defineProperty(process, 'stdout', {
+      configurable: true,
+      enumerable: true,
+      get: () => stdout,
+    })
+
+    return handle
+  } catch {
+    return null
+  }
+}