1 files changed, 87 insertions, 0 deletions
diff --git a/cli/tests/unit/dom_iterable_test.ts b/cli/tests/unit/dom_iterable_test.ts
new file mode 100644
index 000000000..b9435b3bc
--- /dev/null
+++ b/cli/tests/unit/dom_iterable_test.ts
@@ -0,0 +1,87 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { unitTest, assert, assertEquals } from "./test_util.ts";
+
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
+function setup() {
+  const dataSymbol = Symbol("data symbol");
+  class Base {
+    [dataSymbol] = new Map<string, number>();
+
+    constructor(
+      data: Array<[string, number]> | IterableIterator<[string, number]>
+    ) {
+      for (const [key, value] of data) {
+        this[dataSymbol].set(key, value);
+      }
+    }
+  }
+
+  return {
+    Base,
+    // This is using an internal API we don't want published as types, so having
+    // to cast to any to "trick" TypeScript
+    // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
+    DomIterable: Deno[Deno.internal].DomIterableMixin(Base, dataSymbol),
+  };
+}
+
+unitTest(function testDomIterable(): void {
+  const { DomIterable, Base } = setup();
+
+  const fixture: Array<[string, number]> = [
+    ["foo", 1],
+    ["bar", 2],
+  ];
+
+  const domIterable = new DomIterable(fixture);
+
+  assertEquals(Array.from(domIterable.entries()), fixture);
+  assertEquals(Array.from(domIterable.values()), [1, 2]);
+  assertEquals(Array.from(domIterable.keys()), ["foo", "bar"]);
+
+  let result: Array<[string, number]> = [];
+  for (const [key, value] of domIterable) {
+    assert(key != null);
+    assert(value != null);
+    result.push([key, value]);
+  }
+  assertEquals(fixture, result);
+
+  result = [];
+  const scope = {};
+  function callback(
+    this: typeof scope,
+    value: number,
+    key: string,
+    parent: typeof domIterable
+  ): void {
+    assertEquals(parent, domIterable);
+    assert(key != null);
+    assert(value != null);
+    assert(this === scope);
+    result.push([key, value]);
+  }
+  domIterable.forEach(callback, scope);
+  assertEquals(fixture, result);
+
+  assertEquals(DomIterable.name, Base.name);
+});
+
+unitTest(function testDomIterableScope(): void {
+  const { DomIterable } = setup();
+
+  const domIterable = new DomIterable([["foo", 1]]);
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  function checkScope(thisArg: any, expected: any): void {
+    function callback(this: typeof thisArg): void {
+      assertEquals(this, expected);
+    }
+    domIterable.forEach(callback, thisArg);
+  }
+
+  checkScope(0, Object(0));
+  checkScope("", Object(""));
+  checkScope(null, window);
+  checkScope(undefined, window);
+});