1 files changed, 21 insertions, 0 deletions
diff --git a/testing/web-platform/tests/common/sab.js b/testing/web-platform/tests/common/sab.js
new file mode 100644
index 0000000000..a3ea610e16
--- /dev/null
+++ b/testing/web-platform/tests/common/sab.js
@@ -0,0 +1,21 @@
+const createBuffer = (() => {
+  // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
+  let sabConstructor;
+  try {
+    sabConstructor = new WebAssembly.Memory({ shared:true, initial:0, maximum:0 }).buffer.constructor;
+  } catch(e) {
+    sabConstructor = null;
+  }
+  return (type, length, opts) => {
+    if (type === "ArrayBuffer") {
+      return new ArrayBuffer(length, opts);
+    } else if (type === "SharedArrayBuffer") {
+      if (sabConstructor && sabConstructor.name !== "SharedArrayBuffer") {
+        throw new Error("WebAssembly.Memory does not support shared:true");
+      }
+      return new sabConstructor(length, opts);
+    } else {
+      throw new Error("type has to be ArrayBuffer or SharedArrayBuffer");
+    }
+  }
+})();