fix(collections): ensure pick doesn't generate missing properties a…

…s `undefined` (#5926)

collections/pick.ts

@@ -28,5 +28,7 @@ export function pick<T extends object, K extends keyof T>(
   obj: Readonly<T>,
   keys: readonly K[],
 ): Pick<T, K> {
-  return Object.fromEntries(keys.map((k) => [k, obj[k]])) as Pick<T, K>;
+  const result = {} as Pick<T, K>;
+  for (const key of keys) if (key in obj) result[key] = obj[key];
+  return result;
 }

collections/pick_test.ts

@@ -14,6 +14,19 @@ Deno.test({
   },
 });
 
+Deno.test({
+  name:
+    "pick() returns a new object without properties missing in the original object",
+  fn() {
+    // deno-lint-ignore no-explicit-any
+    const obj = { a: 5, b: 6, c: 7, d: 8 } as any;
+    const picked: { a: 5; x?: 5; y?: 5 } = pick(obj, ["a", "x", "y"]);
+
+    assertEquals(picked, { a: 5 });
+    assertNotStrictEquals(picked, obj);
+  },
+});
+
 Deno.test({
   name:
     "pick() returns a new object from the provided object with the provided keys",