1 files changed, 141 insertions, 0 deletions
diff --git a/toolkit/modules/tests/xpcshell/test_PromiseUtils.js b/toolkit/modules/tests/xpcshell/test_PromiseUtils.js
new file mode 100644
index 0000000000..cc80248f00
--- /dev/null
+++ b/toolkit/modules/tests/xpcshell/test_PromiseUtils.js
@@ -0,0 +1,141 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+
+"use strict";
+
+const { PromiseUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/PromiseUtils.sys.mjs"
+);
+const { setTimeout } = ChromeUtils.importESModule(
+  "resource://gre/modules/Timer.sys.mjs"
+);
+const { PromiseTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/PromiseTestUtils.sys.mjs"
+);
+
+// Tests for PromiseUtils.sys.mjs
+
+// Tests for PromiseUtils.defer()
+
+/* Tests for checking the resolve method of the Deferred object
+ * returned by PromiseUtils.defer() */
+add_task(async function test_resolve_string() {
+  let def = PromiseUtils.defer();
+  let expected = "The promise is resolved " + Math.random();
+  def.resolve(expected);
+  let result = await def.promise;
+  Assert.equal(result, expected, "def.resolve() resolves the promise");
+});
+
+/* Test for the case when undefined is passed to the resolve method
+ * of the Deferred object */
+add_task(async function test_resolve_undefined() {
+  let def = PromiseUtils.defer();
+  def.resolve();
+  let result = await def.promise;
+  Assert.equal(result, undefined, "resolve works with undefined as well");
+});
+
+/* Test when a pending promise is passed to the resolve method
+ * of the Deferred object */
+add_task(async function test_resolve_pending_promise() {
+  let def = PromiseUtils.defer();
+  let expected = 100 + Math.random();
+  let p = new Promise((resolve, reject) => {
+    setTimeout(() => resolve(expected), 100);
+  });
+  def.resolve(p);
+  let result = await def.promise;
+  Assert.equal(
+    result,
+    expected,
+    "def.promise assumed the state of the passed promise"
+  );
+});
+
+/* Test when a resovled promise is passed
+ * to the resolve method of the Deferred object */
+add_task(async function test_resolve_resolved_promise() {
+  let def = PromiseUtils.defer();
+  let expected = "Yeah resolved" + Math.random();
+  let p = new Promise((resolve, reject) => resolve(expected));
+  def.resolve(p);
+  let result = await def.promise;
+  Assert.equal(
+    result,
+    expected,
+    "Resolved promise is passed to the resolve method"
+  );
+});
+
+/* Test for the case when a rejected promise is
+ * passed to the resolve method */
+add_task(async function test_resolve_rejected_promise() {
+  let def = PromiseUtils.defer();
+  let p = new Promise((resolve, reject) =>
+    reject(new Error("There its an rejection"))
+  );
+  def.resolve(p);
+  await Assert.rejects(
+    def.promise,
+    /There its an rejection/,
+    "Settled rejection promise passed to the resolve method"
+  );
+});
+
+/* Test for the checking the reject method of
+ * the Deferred object returned by PromiseUtils.defer() */
+add_task(async function test_reject_Error() {
+  let def = PromiseUtils.defer();
+  def.reject(new Error("This one rejects"));
+  await Assert.rejects(
+    def.promise,
+    /This one rejects/,
+    "reject method with Error for rejection"
+  );
+});
+
+/* Test for the case when a pending Promise is passed to
+ * the reject method of Deferred object */
+add_task(async function test_reject_pending_promise() {
+  let def = PromiseUtils.defer();
+  let p = new Promise((resolve, reject) => {
+    setTimeout(() => resolve(100), 100);
+  });
+  def.reject(p);
+  await Assert.rejects(
+    def.promise,
+    Promise,
+    "Rejection with a pending promise uses the passed promise itself as the reason of rejection"
+  );
+});
+
+/* Test for the case when a resolved Promise
+ * is passed to the reject method */
+add_task(async function test_reject_resolved_promise() {
+  let def = PromiseUtils.defer();
+  let p = new Promise((resolve, reject) => resolve("This resolved"));
+  def.reject(p);
+  await Assert.rejects(
+    def.promise,
+    Promise,
+    "Rejection with a resolved promise uses the passed promise itself as the reason of rejection"
+  );
+});
+
+/* Test for the case when a rejected Promise is
+ * passed to the reject method */
+add_task(async function test_reject_resolved_promise() {
+  PromiseTestUtils.expectUncaughtRejection(/This one rejects/);
+  let def = PromiseUtils.defer();
+  let p = new Promise((resolve, reject) =>
+    reject(new Error("This one rejects"))
+  );
+  def.reject(p);
+  await Assert.rejects(
+    def.promise,
+    Promise,
+    "Rejection with a rejected promise uses the passed promise itself as the reason of rejection"
+  );
+});