Adds harness/asyncHelpers.js: functions asyncTest and assert.throwsAsync, per rfcs/async-helpers.md

harness/asyncHelpers.js

@@ -0,0 +1,122 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A collection of assertion and wrapper functions for testing asynchronous built-ins.
+defines: [asyncTest]
+---*/
+
+function asyncTest(testFunc) {
+  if (!Object.hasOwn(globalThis, "$DONE")) {
+    throw new Test262Error("asyncTest called without async flag");
+  }
+  if (typeof testFunc !== "function") {
+    $DONE(new Test262Error("asyncTest called with non-function argument"));
+    return Promise.resolve();
+  }
+  try {
+    return testFunc().then(
+      function () {
+        $DONE();
+      },
+      function (error) {
+        $DONE(error);
+      }
+    );
+  } catch (syncError) {
+    $DONE(syncError);
+    return Promise.resolve();
+  }
+}
+
+assert.throwsAsync = function (
+  expectedErrorConstructor,
+  funcOrThenable,
+  message
+) {
+  var innerThenable;
+  if (message === undefined) {
+    message = "";
+  } else {
+    message += " ";
+  }
+  if (typeof funcOrThenable === "function") {
+    try {
+      innerThenable = funcOrThenable();
+      if (
+        innerThenable === null ||
+        typeof innerThenable !== "object" ||
+        typeof innerThenable.then !== "function"
+      ) {
+        message +=
+          "Expected to obtain an inner promise that would reject with a" +
+          expectedErrorConstructor.name +
+          " but result was not a thenable";
+        return Promise.reject(new Test262Error(message));
+      }
+    } catch (thrown) {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but an exception was thrown synchronously while obtaining the inner promise";
+      return Promise.reject(new Test262Error(message));
+    }
+  } else if (
+    funcOrThenable === null ||
+    typeof funcOrThenable !== "object" ||
+    typeof funcOrThenable.then !== "function"
+  ) {
+    message +=
+      "assert.throwsAsync called with an argument that is neither a function nor a thenable";
+    return Promise.reject(new Test262Error(message));
+  } else {
+    innerThenable = funcOrThenable;
+  }
+
+  try {
+    return innerThenable.then(
+      function () {
+        message +=
+          "Expected a " +
+          expectedErrorConstructor.name +
+          " to be thrown asynchronously but no exception was thrown at all";
+        throw new Test262Error(message);
+      },
+      function (thrown) {
+        var expectedName, actualName;
+        if (typeof thrown !== "object" || thrown === null) {
+          message += "Thrown value was not an object!";
+          throw new Test262Error(message);
+        } else if (thrown.constructor !== expectedErrorConstructor) {
+          expectedName = expectedErrorConstructor.name;
+          actualName = thrown.constructor.name;
+          if (expectedName === actualName) {
+            message +=
+              "Expected a " +
+              expectedName +
+              " but got a different error constructor with the same name";
+          } else {
+            message +=
+              "Expected a " + expectedName + " but got a " + actualName;
+          }
+          throw new Test262Error(message);
+        }
+      }
+    );
+  } catch (thrown) {
+    if (typeof thrown !== "object" || thrown === null) {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but innerThenable synchronously threw a value that was not an object ";
+    } else {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but a " +
+        thrown.constructor.name +
+        " was thrown synchronously";
+    }
+    return Promise.reject(new Test262Error(message));
+  }
+};