chore: add web-login proxy doneUrl regression for npm-profile fix

mock-registry/lib/index.js

@@ -261,15 +261,18 @@ class MockRegistry {
       .reply(200, { token })
   }
 
-  weblogin ({ token = 'npm_default-test-token' }) {
-    const doneUrl = new URL('/npm-cli-test/done', this.origin).href
+  weblogin ({ token = 'npm_default-test-token', doneRegistry } = {}) {
+    const donePath = '/npm-cli-test/done'
+    // doneRegistry emulates a proxy/mirror that advertises a doneUrl on a different origin than the configured registry.
+    // The poll itself is always mocked on this registry, since that is where the session lives.
+    const doneUrl = new URL(donePath, doneRegistry ?? this.origin).href
     const loginUrl = new URL('/npm-cli-test/login/cli/00000000-0000-0000-0000-000000000000', this.origin).href
     this.nock = this.nock
       .post(this.fullPath('/-/v1/login'), () => {
         return true
       })
       .reply(200, { doneUrl, loginUrl })
-      .get('/npm-cli-test/done')
+      .get(donePath)
       .reply(200, { token })
   }
 

test/lib/commands/login.js

@@ -116,7 +116,7 @@
   t.end()
 })
 
 t.test('web', t => {
   t.test('basic login', async t => {
     const { outputs, npm, registry, login, rc } = await mockLogin(t, {
       config: { 'auth-type': 'web' },
@@ -129,6 +129,19 @@
     })
     t.match(outputs[0], '/npm-cli-test/login/cli/00000000-0000-0000-0000-000000000000')
   })
+  t.test('proxy registry whose doneUrl points at the canonical registry', async t => {
+    // Regression for npm/cli#8875: a proxy/mirror returns a doneUrl on registry.npmjs.org.
+    // npm must poll the configured proxy where the session lives, not the canonical registry.
+    const proxy = 'https://proxy.registry.example/'
+    const { npm, registry, login, rc } = await mockLogin(t, {
+      registry: proxy,
+      config: { 'auth-type': 'web', registry: proxy },
+    })
+    registry.weblogin({ token: 'npm_proxy-token', doneRegistry: 'https://registry.npmjs.org' })
+    await login.exec([])
+    t.same(npm.config.get('//proxy.registry.example/:_authToken'), 'npm_proxy-token')
+    t.match(rc(), { '//proxy.registry.example/:_authToken': 'npm_proxy-token' })
+  })
   t.test('server error', async t => {
     const { registry, login } = await mockLogin(t, {
       config: { 'auth-type': 'web' },