1 files changed, 40 insertions, 0 deletions
diff --git a/testing/web-platform/tests/fs/FileSystemSyncAccessHandle-truncate.https.tentative.worker.js b/testing/web-platform/tests/fs/FileSystemSyncAccessHandle-truncate.https.tentative.worker.js
new file mode 100644
index 0000000000..921e0066c9
--- /dev/null
+++ b/testing/web-platform/tests/fs/FileSystemSyncAccessHandle-truncate.https.tentative.worker.js
@@ -0,0 +1,40 @@
+importScripts("/resources/testharness.js");
+importScripts('resources/sync-access-handle-test.js');
+
+'use strict';
+
+sync_access_handle_test((t, handle) => {
+  // Without this assertion, the test passes even if truncate is not defined.
+  assert_implements(handle.truncate,
+    "SyncAccessHandle.truncate is not implemented.");
+
+  handle.truncate(4);
+  assert_equals(handle.getSize(), 4);
+  handle.truncate(2);
+  assert_equals(handle.getSize(), 2);
+  handle.truncate(7);
+  assert_equals(handle.getSize(), 7);
+  handle.truncate(0);
+  assert_equals(handle.getSize(), 0);
+  assert_throws_js(TypeError, () => handle.truncate(-4));
+}, 'test SyncAccessHandle.truncate with different sizes');
+
+sync_access_handle_test((t, handle) => {
+  const writeBuffer = new Uint8Array(4);
+  writeBuffer.set([96, 97, 98, 99]);
+  handle.write(writeBuffer, {at: 0});
+
+  handle.truncate(2);
+  let readBuffer = new Uint8Array(6);
+  assert_equals(2, handle.read(readBuffer, {at: 0}));
+  let expected = new Uint8Array(6);
+  expected.set([96, 97, 0, 0, 0, 0]);
+  assert_array_equals(expected, readBuffer);
+
+  // Resize the file to 6, expect that everything beyond the old size is '0'.
+  handle.truncate(6);
+  assert_equals(6, handle.read(readBuffer, {at: 0}));
+  assert_array_equals(expected, readBuffer);
+}, 'test SyncAccessHandle.truncate after SyncAccessHandle.write');
+
+done();