Explicitly add stream to cache

Pacote doesn't do this automatically anymore

Closes npm/pacote#73 & Closes #2160

lib/cache.js

@@ -105,12 +105,10 @@ with --force.`)
 
     log.silly('cache add', 'spec', spec)
 
-    // we ask pacote for the thing, and then just throw the data
-    // away so that it tee-pipes it into the cache like it does
-    // for a normal request.
     await pacote.tarball.stream(spec, stream => {
       stream.resume()
-      return stream.promise()
+      return cacache.put.stream(this.npm.config.get('cache'), stream)
+        .pipe(stream).promise()
     }, this.npm.flatOptions)
   }
 

test/lib/cache.js

@@ -20,17 +20,20 @@ const npmlog = {
   },
 }
 
+const pipeline = {
+  pipe: () => pipeline,
+  promise: () => Promise.resolve(),
+  resume: () => {},
+}
+
 let tarballStreamSpec = ''
 let tarballStreamOpts = {}
 const pacote = {
   tarball: {
     stream: (spec, handler, opts) => {
       tarballStreamSpec = spec
       tarballStreamOpts = opts
-      return handler({
-        resume: () => {},
-        promise: () => Promise.resolve(),
-      })
+      return handler(pipeline)
     },
   },
 }
@@ -41,10 +44,16 @@ const cacacheVerifyStats = {
   totalEntries: 1,
   runTime: { total: 2000 },
 }
+
 const cacache = {
   verify: (path) => {
     return cacacheVerifyStats
   },
+  put: {
+    stream: (cache, stream) => {
+      return pipeline
+    },
+  },
 }
 
 const Cache = requireInject('../../lib/cache.js', {