Don't throw EndOfStreamError on 0 bytes read, with mayBeLess flag set

Author: Borewit

lib/stream/AbstractStreamReader.ts

@@ -55,7 +55,7 @@ export abstract class AbstractStreamReader implements IStreamReader {
     if (!this.endOfStream) {
       bytesRead += await this.readRemainderFromStream(buffer.subarray(bytesRead), mayBeLess);
     }
-    if (bytesRead === 0) {
+    if (bytesRead === 0 && !mayBeLess) {
       throw new EndOfStreamError();
     }
     return bytesRead;

lib/stream/WebStreamDefaultReader.ts

@@ -55,7 +55,7 @@ export class WebStreamDefaultReader extends AbstractStreamReader {
       }
     }
 
-    if (totalBytesRead === 0 && this.endOfStream) {
+    if (!mayBeLess && totalBytesRead === 0 && this.endOfStream) {
       throw new EndOfStreamError();
     }
 

test/test.ts

@@ -1110,10 +1110,17 @@ describe('fromStream with mayBeLess flag', () => {
             const streamReader = factory.fromString('abcdefg');
 
             const buf = new Uint8Array(0);
-            const bytesRead = await streamReader.read(buf.subarray(0, 0));
+            const bytesRead = await streamReader.read(buf);
             assert.strictEqual(bytesRead, 0, 'Should return');
           });
 
+          it('should not throw an end-of-stream-error when mayBeLess=true', async () => {
+            const streamReader = factory.fromString('');
+            const buf = new Uint8Array(1);
+            const bytesRead = await streamReader.read(buf, true);
+            assert.strictEqual(bytesRead, 0, 'Expect 0 byte read');
+          });
+
           it('read from a streamed data chunk', async () => {
             const streamReader = factory.fromString('\x05peter');