Pawda feature/#67 support no transform (#98)

* [feature/#67-support-no-transform] Implements unit tests for "Cache-Control: no-transform"

* [feature/#67-support-no-transform] Add supports for "Cache-Control: no-transform"

* add change history

Co-authored-by: Memoria <Pawda@users.noreply.github.com>

Author: jonathanong

HISTORY.md

@@ -1,4 +1,8 @@
 
+3.1.0 / 2020-04-15
+
+ * support no-transform @Pawda
+
 3.0.0 / 2018-04-14
 ==================
 

__tests__/index.js

@@ -297,4 +297,61 @@ describe('Compress', () => {
         done()
       })
   })
+
+  describe('Cache-Control', () => {
+    ['no-transform', 'public, no-transform', 'no-transform, private', 'no-transform , max-age=1000', 'max-age=1000 , no-transform'].forEach(headerValue => {
+      it(`should skip Cache-Control: ${headerValue}`, done => {
+        const app = new Koa()
+
+        app.use(compress())
+        app.use((ctx, next) => {
+          ctx.set('Cache-Control', headerValue)
+          next()
+        })
+        app.use(sendString)
+
+        request(app.listen())
+          .get('/')
+          .expect(200)
+          .end((err, res) => {
+            if (err) { return done(err) }
+
+            assert.equal(res.headers['content-length'], '2048')
+            assert.equal(res.headers.vary, 'Accept-Encoding')
+            assert(!res.headers['content-encoding'])
+            assert(!res.headers['transfer-encoding'])
+            assert.equal(res.text, string)
+
+            done()
+          })
+      })
+    });
+
+    ['not-no-transform', 'public', 'no-transform-thingy'].forEach(headerValue => {
+      it(`should not skip Cache-Control: ${headerValue}`, done => {
+        const app = new Koa()
+
+        app.use(compress())
+        app.use((ctx, next) => {
+          ctx.set('Cache-Control', headerValue)
+          next()
+        })
+        app.use(sendString)
+
+        request(app.listen())
+          .get('/')
+          .expect(200)
+          .end((err, res) => {
+            if (err) { return done(err) }
+
+            assert.equal(res.headers['transfer-encoding'], 'chunked')
+            assert.equal(res.headers.vary, 'Accept-Encoding')
+            assert(!res.headers['content-length'])
+            assert.equal(res.text, string)
+
+            done()
+          })
+      })
+    })
+  })
 })

index.js

@@ -20,6 +20,11 @@ const encodingMethods = {
   deflate: zlib.createDeflate
 }
 
+/**
+* Regex to match no-transform directive in a cache-control header
+*/
+const NO_TRANSFORM_REGEX = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
+
 /**
  * Compress middleware.
  *
@@ -48,6 +53,11 @@ module.exports = (options = {}) => {
     // forced compression or implied
     if (!(ctx.compress === true || filter(ctx.response.type))) return
 
+    // Don't compress for Cache-Control: no-transform
+    // https://tools.ietf.org/html/rfc7234#section-5.2.1.6
+    const cacheControl = ctx.response.get('Cache-Control')
+    if (cacheControl && NO_TRANSFORM_REGEX.test(cacheControl)) return
+
     // identity
     const encoding = ctx.acceptsEncodings('gzip', 'deflate', 'identity')
     if (!encoding) ctx.throw(406, 'supported encodings: gzip, deflate, identity')