feat: automatically decorate etag

src/index.js

@@ -13,14 +13,14 @@ const cacheableResponse = ({
   bypassQueryParameter = 'force',
   cache = new Keyv({ namespace: 'ssr' }),
   compress: enableCompression = false,
-  get,
+  get: rawGet,
   key: getKey = createKey(bypassQueryParameter),
   send,
   staleTtl: rawStaleTtl = 3600000,
   ttl: rawTtl = 86400000,
   ...compressOpts
 } = {}) => {
-  assert(get, '.get required')
+  assert(rawGet, '.get required')
   assert(send, '.send required')
 
   const staleTtl = isFunction(rawStaleTtl)
@@ -34,6 +34,11 @@ const cacheableResponse = ({
     ...compressOpts
   })
 
+  const get = opts => Promise.resolve(rawGet(opts)).then(result => {
+    result.etag = getEtag(serialize(result))
+    return result
+  })
+
   const memoGet = memoize(get, cache, {
     key: getKey,
     objectMode: true,
@@ -55,13 +60,12 @@ const cacheableResponse = ({
     const {
       createdAt = Date.now(),
       data = null,
-      etag: cachedEtag,
+      etag,
       staleTtl = memoGet.staleTtl(result),
       ttl = memoGet.ttl(result),
       ...props
     } = result
 
-    const etag = cachedEtag || getEtag(serialize(result))
     const ifNoneMatch = req.headers['if-none-match']
     const isModified = etag !== ifNoneMatch
 

test/etag.js

@@ -0,0 +1,65 @@
+'use strict'
+
+const test = require('ava')
+const got = require('got')
+
+const cacheableResponse = require('..')
+const { runServer } = require('./helpers')
+
+test('etag is present', async t => {
+  const url = await runServer(
+    t,
+    cacheableResponse({
+      staleTtl: false,
+      get: ({ req, res }) => {
+        return {
+          data: { foo: 'bar' },
+          ttl: 30000,
+          createdAt: Date.now(),
+          foo: { bar: true }
+        }
+      },
+      send: ({ data, headers, res, req, ...props }) => {
+        res.end('Hello World')
+      }
+    })
+  )
+  const { headers: headersOne } = await got(`${url}/kikobeats`)
+  t.is(headersOne['x-cache-status'], 'MISS')
+  const { headers: headersTwo } = await got(`${url}/kikobeats`)
+  t.is(headersTwo['x-cache-status'], 'HIT')
+  t.is(headersOne.etag, headersTwo.etag)
+})
+
+test('etag is different', async t => {
+  const url = await runServer(
+    t,
+    cacheableResponse({
+      staleTtl: false,
+      key: ({ req }) => [req.url, req.url.includes('force')],
+      get: ({ req, res }) => {
+        return {
+          data: { foo: 'bar' },
+          ttl: 30000,
+          createdAt: Date.now(),
+          foo: { bar: true }
+        }
+      },
+      send: ({ data, headers, res, req }) => {
+        res.end('Hello World')
+      }
+    })
+  )
+  const { headers: headersOne } = await got(`${url}/kikobeats`)
+  const etagOne = headersOne.etag
+
+  const { headers: headersTwo } = await got(`${url}/kikobeats`)
+  const etagTwo = headersTwo.etag
+
+  t.is(etagOne, etagTwo)
+
+  const { headers: headersThree } = await got(`${url}/kikobeats&force`)
+  const etagThree = headersThree.etag
+
+  t.not(etagOne, etagThree)
+})

test/index.js

@@ -6,31 +6,6 @@ const got = require('got')
 const cacheableResponse = require('..')
 const { runServer } = require('./helpers')
 
-test('etag is present', async t => {
-  const url = await runServer(
-    t,
-    cacheableResponse({
-      staleTtl: false,
-      get: ({ req, res }) => {
-        return {
-          data: { foo: 'bar' },
-          ttl: 30000,
-          createdAt: Date.now(),
-          foo: { bar: true }
-        }
-      },
-      send: ({ data, headers, res, req, ...props }) => {
-        res.end('Hello World')
-      }
-    })
-  )
-  const { headers: headersOne } = await got(`${url}/kikobeats`)
-  t.is(headersOne['x-cache-status'], 'MISS')
-  const { headers: headersTwo } = await got(`${url}/kikobeats`)
-  t.is(headersTwo['x-cache-status'], 'HIT')
-  t.is(headersOne.etag, headersTwo.etag)
-})
-
 test('compress support', async t => {
   const url = await runServer(
     t,