Include stream processing inside cache function

Response will always be a stream now

index.js

@@ -61,15 +61,7 @@ function requestAsEventEmitter(opts) {
 				response.url = redirectUrl || requestUrl;
 				response.requestUrl = requestUrl;
 
-				const policy = new CachePolicy(opts, response);
-				if (opts.cache && policy.storable()) {
-					const encoding = opts.encoding === null ? 'buffer' : opts.encoding;
-					getStream(response, {encoding})
-						.then(body => {
-							response.body = body;
-							cacheResponse(response, policy, opts);
-						});
-				}
+				maybeCacheResponse(response, opts);
 
 				ee.emit('response', response);
 			});
@@ -335,7 +327,15 @@ function normalizeArguments(url, opts) {
 	return opts;
 }
 
-function cacheResponse(response, policy, opts) {
+function maybeCacheResponse(response, opts) {
+	const policy = new CachePolicy(opts, response);
+	if (!(opts.cache && policy.storable())) {
+		return;
+	}
+	const encoding = opts.encoding === null ? 'buffer' : opts.encoding;
+	getStream(response, {encoding})
+		.then(body => {
+			response.body = body;
 			const key = cacheKey(opts);
 			const value = {
 				policy: policy.toObject(),
@@ -349,6 +349,7 @@ function cacheResponse(response, policy, opts) {
 				}
 			};
 			opts.cache.set(key, value);
+		});
 }
 
 function cacheKey(opts) {