1 files changed, 140 insertions, 0 deletions
diff --git a/dom/ipc/tests/test_blob_sliced_from_child_process.js b/dom/ipc/tests/test_blob_sliced_from_child_process.js
new file mode 100644
index 0000000000..8a7a56088d
--- /dev/null
+++ b/dom/ipc/tests/test_blob_sliced_from_child_process.js
@@ -0,0 +1,140 @@
+"use strict";
+
+const { XPCShellContentUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/XPCShellContentUtils.sys.mjs"
+);
+
+XPCShellContentUtils.init(this);
+
+function childFrameScript() {
+  /* eslint-env mozilla/frame-script */
+  "use strict";
+
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobType = "text/plain";
+
+  let blob = new Blob(blobData, { type: blobType });
+
+  let firstSliceStart = blobData[0].length + blobData[1].length;
+  let firstSliceEnd = firstSliceStart + blobData[2].length;
+
+  let slice = blob.slice(firstSliceStart, firstSliceEnd, blobType);
+
+  let secondSliceStart = blobData[2].indexOf("a");
+  let secondSliceEnd = secondSliceStart + 2;
+
+  slice = slice.slice(secondSliceStart, secondSliceEnd, blobType);
+
+  sendAsyncMessage(messageName, { blob });
+  sendAsyncMessage(messageName, { slice });
+}
+
+add_task(async function test() {
+  let page = await XPCShellContentUtils.loadContentPage(
+    "data:text/html,<!DOCTYPE HTML><html><body></body></html>",
+    {
+      remote: true,
+    }
+  );
+
+  page.loadFrameScript(childFrameScript);
+
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobText = blobData.join("");
+  const blobType = "text/plain";
+
+  const sliceText = "an";
+
+  let receivedBlob = false;
+  let receivedSlice = false;
+
+  let resolveBlob, resolveSlice;
+  let blobPromise = new Promise(resolve => {
+    resolveBlob = resolve;
+  });
+  let slicePromise = new Promise(resolve => {
+    resolveSlice = resolve;
+  });
+
+  let mm = page.browser.messageManager;
+  mm.addMessageListener(messageName, function (message) {
+    if ("blob" in message.data) {
+      equal(receivedBlob, false, "Have not yet received Blob");
+      equal(receivedSlice, false, "Have not yet received Slice");
+
+      receivedBlob = true;
+
+      let blob = message.data.blob;
+
+      ok(Blob.isInstance(blob), "Received a Blob");
+      equal(blob.size, blobText.length, "Blob has correct size");
+      equal(blob.type, blobType, "Blob has correct type");
+
+      let slice = blob.slice(
+        blobText.length - blobData[blobData.length - 1].length,
+        blob.size,
+        blobType
+      );
+
+      ok(Blob.isInstance(slice), "Slice returned a Blob");
+      equal(
+        slice.size,
+        blobData[blobData.length - 1].length,
+        "Slice has correct size"
+      );
+      equal(slice.type, blobType, "Slice has correct type");
+
+      let reader = new FileReader();
+      reader.onload = function () {
+        equal(
+          reader.result,
+          blobData[blobData.length - 1],
+          "Slice has correct data"
+        );
+
+        resolveBlob();
+      };
+      reader.readAsText(slice);
+    } else if ("slice" in message.data) {
+      equal(receivedBlob, true, "Already received Blob");
+      equal(receivedSlice, false, "Have not yet received Slice");
+
+      receivedSlice = true;
+
+      let slice = message.data.slice;
+
+      ok(Blob.isInstance(slice), "Received a Blob for slice");
+      equal(slice.size, sliceText.length, "Slice has correct size");
+      equal(slice.type, blobType, "Slice has correct type");
+
+      let reader = new FileReader();
+      reader.onload = function () {
+        equal(reader.result, sliceText, "Slice has correct data");
+
+        let slice2 = slice.slice(1, 2, blobType);
+
+        ok(Blob.isInstance(slice2), "Slice returned a Blob");
+        equal(slice2.size, 1, "Slice has correct size");
+        equal(slice2.type, blobType, "Slice has correct type");
+
+        let reader2 = new FileReader();
+        reader2.onload = function () {
+          equal(reader2.result, sliceText[1], "Slice has correct data");
+
+          resolveSlice();
+        };
+        reader2.readAsText(slice2);
+      };
+      reader.readAsText(slice);
+    } else {
+      ok(false, "Received a bad message: " + JSON.stringify(message.data));
+    }
+  });
+
+  await blobPromise;
+  await slicePromise;
+
+  await page.close();
+});