chore: maybe improve assert type inference

Author: danielpza

src/index.test.ts

@@ -10,14 +10,20 @@ import {
 
 type DataType = { a: string; b: string };
 
+// HasProperties
 assert<HasProperties<DataType, "a">>(true);
 assert<HasProperties<DataType, "a" | "b">>(true);
 assert<HasProperties<DataType, "a" | "b" | "c">>(false);
 assert<HasProperties<DataType, "c">>(false);
+
+// Extends
 assert<Extends<DataType, { c: string }>>(false);
 assert<Extends<DataType, { a: string; b: string }>>(true);
+
+//Equals
 assert<Equals<DataType, { a: string; b: string }>>(true);
 assert<Not<Equals<DataType, { a: string; b: string }>>>(false);
 
+// Extra
 assertTrue<Equals<DataType, { a: string; b: string }>>();
 assertFalse<Extends<DataType, { c: string }>>();

src/index.ts

@@ -8,6 +8,6 @@ export type HasProperties<T, K extends IndexType> = Extends<
 >;
 export type Not<T extends boolean> = T extends true ? false : true;
 
-export function assert<T>(expected: T) {}
+export function assert<T extends boolean>(expected: T) {}
 export function assertTrue<T extends true>() {}
 export function assertFalse<T extends false>() {}