LibJS/Tests: Add some basic tests for Array.fromAsync

Userland/Libraries/LibJS/Tests/builtins/Array/Array.fromAsync.js

@@ -0,0 +1,60 @@
+test("length is 1", () => {
+    expect(Array.fromAsync).toHaveLength(1);
+});
+
+describe("normal behavior", () => {
+    function checkResult(promise) {
+        expect(promise).toBeInstanceOf(Promise);
+        let error = null;
+        let passed = false;
+        promise
+            .then(value => {
+                expect(value instanceof Array).toBeTrue();
+                expect(value[0]).toBe(0);
+                expect(value[1]).toBe(2);
+                expect(value[2]).toBe(4);
+                passed = true;
+            })
+            .catch(value => {
+                error = value;
+            });
+        runQueuedPromiseJobs();
+        expect(error).toBeNull();
+        expect(passed).toBeTrue();
+    }
+
+    test("async from sync iterable no mapfn", () => {
+        const input = [0, Promise.resolve(2), Promise.resolve(4)].values();
+        const promise = Array.fromAsync(input);
+        checkResult(promise);
+    });
+
+    test("from object of promises no mapfn", () => {
+        let promise = Array.fromAsync({
+            length: 3,
+            0: Promise.resolve(0),
+            1: Promise.resolve(2),
+            2: Promise.resolve(4),
+        });
+        checkResult(promise);
+    });
+
+    test("async from sync iterable with mapfn", () => {
+        const input = [Promise.resolve(0), 1, Promise.resolve(2)].values();
+        const promise = Array.fromAsync(input, async element => element * 2);
+        checkResult(promise);
+    });
+
+    test("from object of promises with mapfn", () => {
+        let promise = Array.fromAsync(
+            {
+                length: 3,
+                0: Promise.resolve(0),
+                1: Promise.resolve(1),
+                2: Promise.resolve(2),
+            },
+            async element => element * 2
+        );
+        checkResult(promise);
+    });
+});