feat: add getUserAgent support (#20)

Co-authored-by: Ben McCann <[email protected]>
Co-authored-by: Michaël De Boey <[email protected]>

Author: 3 people

README.md

@@ -26,28 +26,44 @@ yarn add package-manager-detector
 
 ### ESM
 
+To check the file system for which package manager is used:
+
 ```js
 import { detect } from 'package-manager-detector/detect'
 ```
 
-or sync version
+or sync version:
 
 ```js
 import { detectSync } from 'package-manager-detector/detect'
 ```
 
+or to get the currently running package manager:
+
+```js
+import { getUserAgent } from 'package-manager-detector/detect'
+```
+
 ### CommonJS
 
+To check the file system for which package manager is used:
+
 ```js
 const { detect } = require('package-manager-detector/detect')
 ```
 
-or sync version
+or sync version:
 
 ```js
 const { detectSync } = require('package-manager-detector/detect')
 ```
 
+or to get the currently running package manager:
+
+```js
+import { getUserAgent } = require('package-manager-detector/detect')
+```
+
 ## Agents and Commands
 
 This package includes package manager agents and their corresponding commands for:

src/detect.ts

@@ -2,7 +2,7 @@ import fs from 'node:fs'
 import fsPromises from 'node:fs/promises'
 import path from 'node:path'
 import process from 'node:process'
-import type { Agent, DetectOptions, DetectResult } from './types'
+import type { Agent, AgentName, DetectOptions, DetectResult } from './types'
 import { AGENTS, LOCKS } from './constants'
 
 /**
@@ -12,6 +12,7 @@ import { AGENTS, LOCKS } from './constants'
  */
 export async function detect(options: DetectOptions = {}): Promise<DetectResult | null> {
   const { cwd, onUnknown } = options
+
   for (const directory of lookup(cwd)) {
     // Look up for lock files
     for (const lock of Object.keys(LOCKS)) {
@@ -40,6 +41,7 @@ export async function detect(options: DetectOptions = {}): Promise<DetectResult
  */
 export function detectSync(options: DetectOptions = {}): DetectResult | null {
   const { cwd, onUnknown } = options
+
   for (const directory of lookup(cwd)) {
     // Look up for lock files
     for (const lock of Object.keys(LOCKS)) {
@@ -61,6 +63,21 @@ export function detectSync(options: DetectOptions = {}): DetectResult | null {
   return null
 }
 
+/**
+ * Detects the package manager used in the running process.
+ *
+ * This method will check for `process.env.npm_config_user_agent`.
+ */
+export function getUserAgent(): AgentName | null {
+  const userAgent = process.env.npm_config_user_agent
+  if (!userAgent) {
+    return null
+  }
+
+  const name = userAgent.split('/')[0] as AgentName
+  return AGENTS.includes(name) ? name : null
+}
+
 function * lookup(cwd: string = process.cwd()): Generator<string> {
   let directory = path.resolve(cwd)
   const { root } = path.parse(directory)

src/index.ts

@@ -1,5 +1,5 @@
 export * from './constants'
 export * from './types'
 
-export { detect, detectSync } from './detect'
+export { detect, detectSync, getUserAgent } from './detect'
 export { resolveCommand, constructCommand, COMMANDS } from './commands'

test/user-agent.spec.ts

@@ -0,0 +1,22 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { getUserAgent } from '../src/detect'
+
+describe('get user agent', () => {
+  beforeEach(() => {
+    vi.unstubAllEnvs()
+  })
+  ;[
+    ['npm', 'npm/10.9.0 node/v20.17.0 linux x64 workspaces/false'],
+    ['yarn', 'yarn/1.22.11 npm/? node/v14.17.6 darwin x64'],
+    ['pnpm', 'pnpm/9.12.1 npm/? node/v20.17.0 linux x64'],
+    ['bun', 'bun/1.1.8 npm/? node/v21.6.0 linux x64'],
+  ].forEach(([agent, detection]) => {
+    it(`${agent} detected with ${detection}`, () => {
+      vi.stubEnv(
+        'npm_config_user_agent',
+        detection,
+      )
+      expect(getUserAgent()).toBe(agent)
+    })
+  })
+})