fix the object constraint for NonEmptyObject<T> (#336)

* fix the object constraint for `NonEmptyObject<T>`

* refactor test for `NonEmptyObject`  to new file

* docs: 📄 update changeset

Update .changeset/great-hounds-brush.md

Co-authored-by: Alexey Berezin <2991847+Beraliv@users.noreply.github.com>

.changeset/great-hounds-brush.md

@@ -0,0 +1,5 @@
+---
+"ts-essentials": patch
+---
+
+Improve the object constraint for `NonEmptyObject<T>` to not allow primitives

lib/types.ts

@@ -386,7 +386,7 @@ type DeepModify<T> =
 /** Remove keys with `never` value from object type */
 export type NonNever<T extends {}> = Pick<T, { [K in keyof T]: T[K] extends never ? never : K }[keyof T]>;
 
-export type NonEmptyObject<T extends {}> = keyof T extends never ? never : T;
+export type NonEmptyObject<T extends AnyRecord> = keyof T extends never ? never : T;
 
 export type NonEmptyArray<T> = [T, ...T[]];
 

test/index.ts

@@ -15,7 +15,6 @@ import {
   DictionaryValues,
   Merge,
   MergeN,
-  NonEmptyObject,
   NonNever,
   noop,
   PickProperties,
@@ -44,6 +43,7 @@ import {
   ArrayOrSingle,
   IsAny,
   NonEmptyArray,
+  Primitive,
 } from "../lib";
 import { TsVersion } from "./ts-version";
 import { ComplexNestedPartial, ComplexNestedRequired } from "./types";
@@ -832,14 +832,6 @@ function testNonNever() {
   type TestB = Assert<IsExact<keyof NonNever<Mapped>, "foo" | "bar">>;
 }
 
-function testNonEmptyObject() {
-  type ObjectWithKeys = { foo: string; bar: number; xyz: undefined };
-  type EmptyObject = {};
-
-  type TestA = Assert<IsExact<NonEmptyObject<ObjectWithKeys>, ObjectWithKeys>>;
-  type TestB = Assert<IsExact<NonEmptyObject<EmptyObject>, never>>;
-}
-
 function testNonEmptyArray() {
   type Cases<T> = [
     Assert<IsExact<NonEmptyArray<T>, [T, ...T[]]>>,

test/non-empty-object.ts

@@ -0,0 +1,22 @@
+import { AssertTrue as Assert, IsExact } from "conditional-type-checks";
+import { NonEmptyObject } from "../lib";
+
+function testNonEmptyObject() {
+  type ObjectWithKeys = { foo: string; bar: number; xyz: undefined };
+  type EmptyObject = {};
+
+  type Cases = [
+    Assert<IsExact<NonEmptyObject<ObjectWithKeys>, ObjectWithKeys>>,
+    Assert<IsExact<NonEmptyObject<EmptyObject>, never>>,
+    // Works with Wrapper Object Types
+    Assert<IsExact<NonEmptyObject<String>, String>>,
+    Assert<IsExact<NonEmptyObject<Number>, Number>>,
+    Assert<IsExact<NonEmptyObject<Boolean>, Boolean>>,
+    //   @ts-expect-error
+    Assert<IsExact<NonEmptyObject<string>, string>>, // Will Not work as T is a Primitive
+    // @ts-expect-error
+    Assert<IsExact<NonEmptyObject<number>, number>>, // Will Not work as T is a Primitive
+    // @ts-expect-error
+    Assert<IsExact<NonEmptyObject<undefined>, number>>, // Will Not work as T is a Primitive
+  ];
+}