Handle zero-length OK deflate responses (#903)

src/index.js

@@ -275,6 +275,13 @@ export default function fetch(url, opts) {
 					response = new Response(body, response_options);
 					resolve(response);
 				});
+				raw.on('end', () => {
+					// some old IIS servers return zero-length OK deflate responses, so 'data' is never emitted.
+					if (!response) {
+						response = new Response(body, response_options);
+						resolve(response);
+					}
+				})
 				return;
 			}
 

test/server.js

@@ -120,6 +120,13 @@ export default class TestServer {
 			});
 		}
 
+		if (p === '/empty/deflate') {
+			res.statusCode = 200;
+			res.setHeader('Content-Type', 'text/plain');
+			res.setHeader('Content-Encoding', 'deflate');
+			res.end();
+		}
+
 		if (p === '/sdch') {
 			res.statusCode = 200;
 			res.setHeader('Content-Type', 'text/plain');

test/test.js

@@ -679,6 +679,17 @@ describe('node-fetch', () => {
 		});
 	});
 
+	it('should handle empty deflate response', function() {
+		const url = `${base}empty/deflate`;
+		return fetch(url).then(res => {
+			expect(res.headers.get('content-type')).to.equal('text/plain');
+			return res.text().then(result => {
+				expect(result).to.be.a('string');
+				expect(result).to.be.empty;
+			});
+		});
+	});
+
 	it('should decompress brotli response', function() {
 		if(typeof zlib.createBrotliDecompress !== 'function') this.skip();
 		const url = `${base}brotli`;