From 24e37452960358a592c8a7526fc3d2081f78f388 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 26 Oct 2018 15:32:10 -0700
Subject: [PATCH] Add regression test

---
 .../cases/conformance/types/mapped/mappedTypeErrors.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tests/cases/conformance/types/mapped/mappedTypeErrors.ts b/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
index cec1fbf8395..a38979054ec 100644
--- a/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
+++ b/tests/cases/conformance/types/mapped/mappedTypeErrors.ts
@@ -144,3 +144,13 @@ let f: Foo2<O, 'x'> = {
     pf: {x: 7},
     pt: {x: 7, y: false},
 };
+
+// Repro from #28170
+
+function test1<T, K extends keyof T>(obj: Pick<T, K>) {
+    let x = obj.foo;  // Error
+}
+
+function test2<T, K extends keyof T>(obj: Record<K, number>) {
+    let x = obj.foo;  // Error
+}