From f73308b248d99a30a741314e2a8e5aba9415e311 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Thu, 2 May 2019 15:24:56 -0700
Subject: [PATCH] Add tests

---
 .../reverseMappedPartiallyInferableTypes.ts   | 96 +++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts

diff --git a/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts b/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts
new file mode 100644
index 000000000000..799ff641c5a4
--- /dev/null
+++ b/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts
@@ -0,0 +1,96 @@
+// @strict: true
+
+// Repro from #30505
+
+export type Prop<T> = { (): T }
+export type PropType<T> = Prop<T>;
+export type PropDefaultValue<T> = T;
+
+
+export type PropValidatorFunction<T> = (value: T) => boolean;
+export type PropValidator<T> = PropOptions<T>;
+
+
+export type PropOptions<T> = {
+    type: PropType<T>;
+
+    value?: PropDefaultValue<T>,
+    required?: boolean;
+    validator?: PropValidatorFunction<T>;
+}
+
+export type RecordPropsDefinition<T> = {
+    [K in keyof T]: PropValidator<T[K]>
+}
+export type PropsDefinition<T> = RecordPropsDefinition<T>;
+
+
+declare function extend<T>({ props }: { props: PropsDefinition<T> }):  PropsDefinition<T>;
+
+interface MyType {
+    valid: boolean;
+}
+
+const r = extend({
+    props: {
+        notResolved: {
+            type: Object as PropType<MyType>,
+            validator: x => {
+                return x.valid;
+            }
+        },
+        explicit: {
+            type: Object as PropType<MyType>,
+            validator: (x: MyType) => {
+                return x.valid;
+            }
+        }
+    }
+})
+
+r.explicit
+r.notResolved
+r.explicit.required
+r.notResolved.required
+
+// Modified repro from #30505
+
+type Box<T> = {
+    contents?: T;
+    contains?(content: T): boolean;
+};
+
+type Mapped<T> = {
+    [K in keyof T]: Box<T[K]>;
+}
+
+declare function id<T>(arg: Mapped<T>): Mapped<T>;
+
+// All properties have inferable types
+
+const obj1 = id({
+    foo: {
+        contents: ""
+    }
+});
+
+// Some properties have inferable types
+
+const obj2 = id({
+    foo: {
+        contents: "",
+        contains(k) {
+            return k.length > 0;
+        }
+    }
+});
+
+// No properties have inferable types
+
+const obj3 = id({
+    foo: {
+        contains(k) {
+            return k.length > 0;
+        }
+    }
+});