support reading blob with stream (#608)

src/blob.js

@@ -1,6 +1,8 @@
 // Based on https://github.com/tmpvar/jsdom/blob/aa85b2abf07766ff7bf5c1f6daafb3726f2f2db5/lib/jsdom/living/blob.js
 // (MIT licensed)
 
+import { Readable } from 'stream';
+
 export const BUFFER = Symbol('buffer');
 const TYPE = Symbol('type');
 
@@ -57,13 +59,16 @@ export default class Blob {
 		const ab = buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
 		return Promise.resolve(ab);
 	}
-	// stream() {
-	//	 const readable = new Readable()
-	//	 readable._read = () => {}
-	//	 readable.push(this[BUFFER])
-	//	 readable.push(null)
-	//	 return readable || whatwg stream? not decided
-	// }
+	stream() {
+		 const readable = new Readable();
+		 readable._read = () => {};
+		 readable.push(this[BUFFER]);
+		 readable.push(null);
+		 return readable;
+	}
+	toString() {
+		return '[object Blob]'
+	}
 	slice() {
 		const size = this.size;
 

test/test.js

@@ -1779,8 +1779,8 @@ describe('node-fetch', () => {
 			.then(blob => blob.text())
 			.then(body => {
 				expect(body).to.equal('hello');
-			})
-	})
+			});
+	});
 
 	it('should support reading blob as arrayBuffer', function() {
 		return new Response(`hello`)
@@ -1789,8 +1789,17 @@ describe('node-fetch', () => {
 			.then(ab => {
 				const str = String.fromCharCode.apply(null, new Uint8Array(ab));
 				expect(str).to.equal('hello');
-			})
-	})
+			});
+	});
+
+	it('should support reading blob as stream', function() {
+		return new Response(`hello`)
+			.blob()
+			.then(blob => streamToPromise(blob.stream(), data => {
+				const str = data.toString();
+				expect(str).to.equal('hello');
+			}));
+	});
 
 	it('should support blob round-trip', function() {
 		const url = `${base}hello`;