Micro TypeScript assertion (test) library.
Add your assertions to your usual test suite and run
tsc --noEmit, enjoy!
📌 Please note that this library does not perform any check at runtime, but only at compile time (or in your IDE).
An attempt to reduce the verbosity of type testing.
pnpm add @skarab/tssert typescriptimport { expectType } from '@skarab/tssert';
expectType<boolean>().toAccept(true);
expectType<true>().toAccept(false); // ts-error with descriptionexpectType('Hello').toExtend('42').toBe(true);
expectType<string>().toExtend('42').toBe(true);
expectType('Hello').toExtend<string>().toBe(true);
expectType<string>().toExtend<string>().toBe(true);
expectType<boolean>().toExtend<true>().toBe(true); // ts-error
expectType<true>().toExtend<boolean>().toBe(true);When you move the mouse over
toAccept,toExtendandtoEqualyou can see the expected and received values.
interface TypeA {
a: 42;
b: string | number;
}
interface TypeB {
a: 42;
b: number;
}
expectType<TypeB>().toExtend<TypeA>().toBe(true);
expectType<TypeA>().toExtend<TypeB>().toBe(true); // ts-errorexpectType<TypeA>().toEqual<TypeA>().toBe(true);
expectType<TypeA>().toEqual<TypeB>().toBe(true); // ts-error
expectType<TypeB>().toEqual<TypeA>().toBe(true); // ts-errorimport type { ExpectExtend, ExpectEqual } from '@skarab/tssert';
type A = ExpectExtend<TypeB, TypeA>; // true
type B = ExpectEqual<TypeA, TypeB>; // falseIt is strongly recommended to activate the strict mode of TypeScript which will activate all checking behaviours that results in stronger guarantees of the program's correctness.
See CONTRIBUTING.md