From 12c7576fedcdd83e51fde9561f5c7b71cbe3de78 Mon Sep 17 00:00:00 2001
From: Jonathan Viney <jonathan.viney@gmail.com>
Date: Tue, 5 Feb 2019 17:41:32 +1300
Subject: [PATCH] [@ember/object]: Make ObjectProxy content generic. Add type
 checks for EmberObject getters.

---
 types/ember__object/proxy.d.ts    | 24 +++++++++++++++++--
 types/ember__object/test/proxy.ts | 38 +++++++++++++++++++++++++++++++
 types/ember__object/tsconfig.json |  1 +
 3 files changed, 61 insertions(+), 2 deletions(-)
 create mode 100644 types/ember__object/test/proxy.ts

diff --git a/types/ember__object/proxy.d.ts b/types/ember__object/proxy.d.ts
index 841b211e49..38c690fe72 100644
--- a/types/ember__object/proxy.d.ts
+++ b/types/ember__object/proxy.d.ts
@@ -1,12 +1,32 @@
 import EmberObject from "@ember/object";
+import {
+    UnwrapComputedPropertyGetter,
+    UnwrapComputedPropertyGetters
+} from "@ember/object/-private/types";
 
 /**
  * `Ember.ObjectProxy` forwards all properties not defined by the proxy itself
  * to a proxied `content` object.
  */
-export default class ObjectProxy extends EmberObject {
+export default class ObjectProxy<T extends object = object> extends EmberObject {
     /**
      * The object whose properties will be forwarded.
      */
-    content: object;
+    content: T | undefined;
+
+    get<K extends keyof this>(key: K): UnwrapComputedPropertyGetter<this[K]>;
+    get<K extends keyof T>(key: K): UnwrapComputedPropertyGetter<T[K]> | undefined;
+
+    getProperties<K extends keyof this>(
+        list: K[]
+    ): Pick<UnwrapComputedPropertyGetters<this>, K>;
+    getProperties<K extends keyof this>(
+        ...list: K[]
+    ): Pick<UnwrapComputedPropertyGetters<this>, K>;
+    getProperties<K extends keyof T>(
+        list: K[]
+    ): Pick<Partial<UnwrapComputedPropertyGetters<T>>, K>;
+    getProperties<K extends keyof T>(
+        ...list: K[]
+    ): Pick<Partial<UnwrapComputedPropertyGetters<T>>, K>;
 }
diff --git a/types/ember__object/test/proxy.ts b/types/ember__object/test/proxy.ts
new file mode 100644
index 0000000000..bacfd013f1
--- /dev/null
+++ b/types/ember__object/test/proxy.ts
@@ -0,0 +1,38 @@
+import ObjectProxy from "@ember/object/proxy";
+
+interface Book {
+  title: string;
+  subtitle: string;
+  chapters: Array<{ title: string }>;
+}
+
+class DefaultProxy extends ObjectProxy {}
+DefaultProxy.create().content; // $ExpectType object | undefined
+
+class BookProxy extends ObjectProxy<Book> {
+  private readonly baz = 'baz';
+
+  getTitle() {
+    return this.get('title');
+  }
+
+  getPropertiesTitleSubtitle() {
+    return this.getProperties('title', 'subtitle');
+  }
+}
+
+const book = BookProxy.create();
+book.content; // $ExpectType Book | undefined
+
+book.get("unknownProperty"); // $ExpectError
+book.get("title"); // $ExpectType string | undefined
+book.getTitle(); // $ExpectType string | undefined
+
+book.getProperties("title", "unknownProperty"); // $ExpectError
+book.getProperties("title", "subtitle"); // $ExpectType Pick<Partial<UnwrapComputedPropertyGetters<Book>>, "title" | "subtitle">
+book.getPropertiesTitleSubtitle(); // $ExpectType Pick<Partial<UnwrapComputedPropertyGetters<Book>>, "title" | "subtitle">
+
+book.getProperties(["subtitle", "chapters"]); // $ExpectType Pick<Partial<UnwrapComputedPropertyGetters<Book>>, "subtitle" | "chapters">
+book.getProperties(["title", "unknownProperty"]); // $ExpectError
+
+book.get("baz"); // $ExpectError
diff --git a/types/ember__object/tsconfig.json b/types/ember__object/tsconfig.json
index 5ed61a24d3..deeb128e7b 100644
--- a/types/ember__object/tsconfig.json
+++ b/types/ember__object/tsconfig.json
@@ -49,6 +49,7 @@
         "test/extend.ts",
         "test/object.ts",
         "test/observable.ts",
+        "test/proxy.ts",
         "test/reopen.ts"
     ]
 }