1 files changed, 37 insertions, 0 deletions
diff --git a/dom/tests/mochitest/fetch/utils.js b/dom/tests/mochitest/fetch/utils.js
new file mode 100644
index 000000000..5d294041e
--- /dev/null
+++ b/dom/tests/mochitest/fetch/utils.js
@@ -0,0 +1,37 @@
+// Utilities
+// =========
+
+// Helper that uses FileReader or FileReaderSync based on context and returns
+// a Promise that resolves with the text or rejects with error.
+function readAsText(blob) {
+  if (typeof FileReader !== "undefined") {
+    return new Promise(function(resolve, reject) {
+      var fs = new FileReader();
+      fs.onload = function() {
+        resolve(fs.result);
+      }
+      fs.onerror = reject;
+      fs.readAsText(blob);
+    });
+  } else {
+    var fs = new FileReaderSync();
+    return Promise.resolve(fs.readAsText(blob));
+  }
+}
+
+function readAsArrayBuffer(blob) {
+  if (typeof FileReader !== "undefined") {
+    return new Promise(function(resolve, reject) {
+      var fs = new FileReader();
+      fs.onload = function() {
+        resolve(fs.result);
+      }
+      fs.onerror = reject;
+      fs.readAsArrayBuffer(blob);
+    });
+  } else {
+    var fs = new FileReaderSync();
+    return Promise.resolve(fs.readAsArrayBuffer(blob));
+  }
+}
+