From 75edeefd4a52c528b2c132964734fd68cdc645d3 Mon Sep 17 00:00:00 2001
From: Haozheng Li <emiya@emiya.com.cn>
Date: Wed, 25 Oct 2023 17:27:39 +0800
Subject: [PATCH] `PartialDeep`: Skip constructor (#730)

---
 source/partial-deep.d.ts | 26 ++++++++++++--------------
 test-d/partial-deep.ts   | 10 ++++++++++
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/source/partial-deep.d.ts b/source/partial-deep.d.ts
index 14eb2d49..b2299be6 100644
--- a/source/partial-deep.d.ts
+++ b/source/partial-deep.d.ts
@@ -59,7 +59,7 @@ const partialSettings: PartialDeep<Settings, {recurseIntoArrays: true}> = {
 @category Set
 @category Map
 */
-export type PartialDeep<T, Options extends PartialDeepOptions = {}> = T extends BuiltIns
+export type PartialDeep<T, Options extends PartialDeepOptions = {}> = T extends BuiltIns | (((...arguments_: any[]) => unknown)) | (new (...arguments_: any[]) => unknown)
 	? T
 	: T extends Map<infer KeyType, infer ValueType>
 		? PartialMapDeep<KeyType, ValueType, Options>
@@ -69,19 +69,17 @@ export type PartialDeep<T, Options extends PartialDeepOptions = {}> = T extends
 				? PartialReadonlyMapDeep<KeyType, ValueType, Options>
 				: T extends ReadonlySet<infer ItemType>
 					? PartialReadonlySetDeep<ItemType, Options>
-					: T extends ((...arguments_: any[]) => unknown)
-						? T | undefined
-						: T extends object
-							? T extends ReadonlyArray<infer ItemType> // Test for arrays/tuples, per https://github.com/microsoft/TypeScript/issues/35156
-								? Options['recurseIntoArrays'] extends true
-									? ItemType[] extends T // Test for arrays (non-tuples) specifically
-										? readonly ItemType[] extends T // Differentiate readonly and mutable arrays
-											? ReadonlyArray<PartialDeep<ItemType | undefined, Options>>
-											: Array<PartialDeep<ItemType | undefined, Options>>
-										: PartialObjectDeep<T, Options> // Tuples behave properly
-									: T // If they don't opt into array testing, just use the original type
-								: PartialObjectDeep<T, Options>
-							: unknown;
+					: T extends object
+						? T extends ReadonlyArray<infer ItemType> // Test for arrays/tuples, per https://github.com/microsoft/TypeScript/issues/35156
+							? Options['recurseIntoArrays'] extends true
+								? ItemType[] extends T // Test for arrays (non-tuples) specifically
+									? readonly ItemType[] extends T // Differentiate readonly and mutable arrays
+										? ReadonlyArray<PartialDeep<ItemType | undefined, Options>>
+										: Array<PartialDeep<ItemType | undefined, Options>>
+									: PartialObjectDeep<T, Options> // Tuples behave properly
+								: T // If they don't opt into array testing, just use the original type
+							: PartialObjectDeep<T, Options>
+						: unknown;
 
 /**
 Same as `PartialDeep`, but accepts only `Map`s and as inputs. Internal helper for `PartialDeep`.
diff --git a/test-d/partial-deep.ts b/test-d/partial-deep.ts
index 93019446..2560d85e 100644
--- a/test-d/partial-deep.ts
+++ b/test-d/partial-deep.ts
@@ -1,10 +1,15 @@
 import {expectType, expectError, expectAssignable} from 'tsd';
 import type {PartialDeep} from '../index';
 
+class ClassA {
+	foo = 1;
+}
+
 const foo = {
 	baz: 'fred',
 	bar: {
 		function: (_: string): void => undefined,
+		classConstructor: ClassA,
 		object: {key: 'value'},
 		string: 'waldo',
 		number: 1,
@@ -30,6 +35,11 @@ let partialDeepFoo: PartialDeep<typeof foo, {recurseIntoArrays: true}> = foo;
 expectError(expectType<Partial<typeof foo>>(partialDeepFoo));
 const partialDeepBar: PartialDeep<typeof foo.bar, {recurseIntoArrays: true}> = foo.bar;
 expectType<typeof partialDeepBar | undefined>(partialDeepFoo.bar);
+// Check for constructor
+expectType<typeof ClassA | undefined>(partialDeepFoo.bar!.classConstructor);
+const instance = new partialDeepFoo.bar!.classConstructor!();
+instance.foo = 2;
+const b = partialDeepFoo.bar!.constructor;
 expectType<((_: string) => void) | undefined>(partialDeepFoo.bar!.function);
 expectAssignable<object | undefined>(partialDeepFoo.bar!.object);
 expectType<string | undefined>(partialDeepFoo.bar!.string);