Add tests

Author: bgenia

tests/cases/fourslash/mappedTypesWithKeyofConstraintsOverObjectsWithUnionPropertyNamesShouldProduceMembers.ts

@@ -0,0 +1,26 @@
+/// <reference path='fourslash.ts'/>
+
+//// enum Key {
+////     A = "a",
+////     B = "b"
+//// }
+////
+//// // Produces members with union name types (Key.A | "a", Key.B | "b")
+//// type [|Foo|] = { [K in Key | `${Key}`]: 1 }
+////
+//// // Should produce the same type as Foo
+//// type [|Bar|] = { [K in keyof Foo]: 1 }
+
+const [Foo, Bar] = test.ranges()
+
+verify.quickInfoAt(Foo,
+`type Foo = {
+    a: 1;
+    b: 1;
+}`)
+
+verify.quickInfoAt(Bar,
+`type Bar = {
+    a: 1;
+    b: 1;
+}`)