fix(mock-utils): match header when using fetch (nodejs#1393)

lib/mock/mock-utils.js

@@ -31,6 +31,26 @@ function lowerCaseEntries (headers) {
   )
 }
 
+/**
+ * @param {import('../../index').Headers|string[]|Record<string, string>} headers
+ * @param {string} key
+ */
+function getHeaderByName (headers, key) {
+  if (Array.isArray(headers)) {
+    for (let i = 0; i < headers.length; i += 2) {
+      if (headers[i] === key) {
+        return headers[i + 1]
+      }
+    }
+
+    return undefined
+  } else if (typeof headers.get === 'function') {
+    return headers.get(key)
+  } else {
+    return headers[key]
+  }
+}
+
 function matchHeaders (mockDispatch, headers) {
   if (typeof mockDispatch.headers === 'function') {
     if (Array.isArray(headers)) { // fetch HeadersList
@@ -51,9 +71,9 @@ function matchHeaders (mockDispatch, headers) {
   }
 
   for (const [matchHeaderName, matchHeaderValue] of Object.entries(mockDispatch.headers)) {
-    const header = typeof headers.get === 'function' ? headers.get(matchHeaderName) : headers[matchHeaderName]
+    const headerValue = getHeaderByName(headers, matchHeaderName)
 
-    if (!matchValue(matchHeaderValue, header)) {
+    if (!matchValue(matchHeaderValue, headerValue)) {
       return false
     }
   }
@@ -337,5 +357,6 @@ module.exports = {
   mockDispatch,
   buildMockDispatch,
   checkNetConnect,
-  buildMockOptions
+  buildMockOptions,
+  getHeaderByName
 }

test/mock-pool.js

@@ -11,6 +11,8 @@ const { MockInterceptor } = require('../lib/mock/mock-interceptor')
 const { getResponse } = require('../lib/mock/mock-utils')
 const Dispatcher = require('../lib/dispatcher')
 
+const nodeMajor = Number(process.versions.node.split('.', 1)[0])
+
 test('MockPool - constructor', t => {
   t.plan(3)
 
@@ -300,3 +302,48 @@ test('MockPool - basic intercept with MockPool.request', async (t) => {
     foo: 'bar'
   })
 })
+
+test('MockPool - allows matching headers in fetch', { skip: nodeMajor < 16 }, async (t) => {
+  const { fetch, getGlobalDispatcher, setGlobalDispatcher } = require('../index')
+
+  const oldDispatcher = getGlobalDispatcher()
+
+  const baseUrl = 'http://localhost:9999'
+  const mockAgent = new MockAgent()
+  mockAgent.disableNetConnect()
+  setGlobalDispatcher(mockAgent)
+
+  t.teardown(async () => {
+    await mockAgent.close()
+    setGlobalDispatcher(oldDispatcher)
+  })
+
+  const pool = mockAgent.get(baseUrl)
+  pool.intercept({
+    path: '/foo',
+    method: 'GET',
+    headers: {
+      accept: 'application/json'
+    }
+  }).reply(200, { ok: 1 }).times(3)
+
+  await t.resolves(
+    fetch(`${baseUrl}/foo`, {
+      headers: {
+        accept: 'application/json'
+      }
+    })
+  )
+
+  // no 'accept: application/json' header sent, not matched
+  await t.rejects(fetch(`${baseUrl}/foo`))
+
+  // not 'accept: application/json', not matched
+  await t.rejects(fetch(`${baseUrl}/foo`), {
+    headers: {
+      accept: 'text/plain'
+    }
+  }, TypeError)
+
+  t.end()
+})

test/mock-utils.js

@@ -6,7 +6,8 @@ const {
   deleteMockDispatch,
   getMockDispatch,
   getResponseData,
-  getStatusText
+  getStatusText,
+  getHeaderByName
 } = require('../lib/mock/mock-utils')
 
 test('deleteMockDispatch - should do nothing if not able to find mock dispatch', (t) => {
@@ -129,3 +130,30 @@ test('getStatusText', (t) => {
 
   t.end()
 })
+
+test('getHeaderByName', (t) => {
+  const headersRecord = {
+    key: 'value'
+  }
+
+  t.equal(getHeaderByName(headersRecord, 'key'), 'value')
+  t.equal(getHeaderByName(headersRecord, 'anotherKey'), undefined)
+
+  const headersArray = ['key', 'value']
+
+  t.equal(getHeaderByName(headersArray, 'key'), 'value')
+  t.equal(getHeaderByName(headersArray, 'anotherKey'), undefined)
+
+  if (Number(process.versions.node.split('.')[0]) >= 16) {
+    const { Headers } = require('../index')
+
+    const headers = new Headers([
+      ['key', 'value']
+    ])
+
+    t.equal(getHeaderByName(headers, 'key'), 'value')
+    t.equal(getHeaderByName(headers, 'anotherKey'), null)
+  }
+
+  t.end()
+})