From 476e222c93433c387092b6aecef8a9a4c7d06ff0 Mon Sep 17 00:00:00 2001
From: Yury Semikhatsky <yurys@chromium.org>
Date: Fri, 6 Aug 2021 12:35:20 -0700
Subject: [PATCH] fix: support 0 size read from stream (#539)

---
 .../java/com/microsoft/playwright/impl/Stream.java  |  3 +++
 .../java/com/microsoft/playwright/TestDownload.java | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/playwright/src/main/java/com/microsoft/playwright/impl/Stream.java b/playwright/src/main/java/com/microsoft/playwright/impl/Stream.java
index eac797c2..8ee469dd 100644
--- a/playwright/src/main/java/com/microsoft/playwright/impl/Stream.java
+++ b/playwright/src/main/java/com/microsoft/playwright/impl/Stream.java
@@ -45,6 +45,9 @@ public class Stream extends ChannelOwner {
 
     @Override
     public int read(byte[] b, int off, int len) {
+      if (len == 0) {
+        return 0;
+      }
       JsonObject params = new JsonObject();
       params.addProperty("size", len);
       JsonObject json = sendMessage("read", params).getAsJsonObject();
diff --git a/playwright/src/test/java/com/microsoft/playwright/TestDownload.java b/playwright/src/test/java/com/microsoft/playwright/TestDownload.java
index bb0e123c..6588c291 100644
--- a/playwright/src/test/java/com/microsoft/playwright/TestDownload.java
+++ b/playwright/src/test/java/com/microsoft/playwright/TestDownload.java
@@ -367,6 +367,19 @@ public class TestDownload extends TestBase {
     page.close();
   }
 
+  @Test
+  void streamShouldSupportZeroSizeRead() throws IOException {
+    Page page = browser.newPage(new Browser.NewPageOptions().setAcceptDownloads(true));
+    page.setContent("<a href='" + server.PREFIX + "/download'>download</a>");
+    Download download = page.waitForDownload(() -> page.click("a"));
+
+    InputStream stream = download.createReadStream();
+    byte[] b = new byte[1];
+    int read = stream.read(b, 0, 0);
+    assertEquals(0, read);
+    page.close();
+  }
+
   @Test
   void shouldDeleteDownloadsOnContextDestruction() {
     Page page = browser.newPage(new Browser.NewPageOptions().setAcceptDownloads(true));