Add tests

tests/cases/conformance/types/mapped/mappedTypesAndObjects.ts

@@ -13,23 +13,33 @@ function f2<T>(x: Partial<T>, y: Readonly<T>) {
     obj = y;
 }
 
+function f3<T>(x: Partial<T>) {
+    x = {};
+}
+
 // Repro from #12900
 
 interface Base {
-   foo: { [key: string]: any };
-   bar: any;
-   baz: any;
+    foo: { [key: string]: any };
+    bar: any;
+    baz: any;
 }
 
 interface E1<T> extends Base {
-  foo: T;
+    foo: T;
 }
 
 interface Something { name: string, value: string };
 interface E2 extends Base {
-  foo: Partial<Something>;  // or other mapped type
+    foo: Partial<Something>;  // or other mapped type
 }
 
 interface E3<T> extends Base {
-  foo: Partial<T>; // or other mapped type
-}
+    foo: Partial<T>; // or other mapped type
+}
+
+// Repro from #13747
+
+class Form<T> {
+    private values: {[P in keyof T]?: T[P]} = {}
+}