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Is it possible to assert compilation error in TypeScript?

For example in Scala one can do following (ScalaTest):

assertDoesNotCompile("val a: String = 1")
assertTypeError("val a: String = 1")
assertCompiles("val a: Int = 1")

Does something similar exist in TypeScript world?

Edit:
I mean context-aware compilation. For example code from this question How do I write a scala unit test that ensures compliation fails?:

import shapeless.test.illTyped

//this version won't even compile
illTyped("getIdx(C.Ooga)")

//We can have multiple enum unions exist side by side
import Union_B_C._
B.values().foreach {b => Union_B_C.getIdx(b) should be (b.ordinal())}
C.values().foreach {c => Union_B_C.getIdx(c) should be (c.ordinal() + 2)}

//Though A exists in some union type, Union_B_C still doesn't know about it,
// so this won't compile
illTyped("""
  A.values().foreach {a => Union_B_C.getIdx(a) should be (a.ordinal())}
""")
like image 359
monnef Avatar asked Sep 02 '25 14:09

monnef


1 Answers

It is not a feature of Scala, it's a feature of ScalaTest which uses scala compiler at runtime as a library.

You can use typescript compiler as a library, it has rather complicated API documented here.

I have a node module published on github that simplifies things a bit, you can use it like this:

import {createCompiler, CompileResult} from 'tsc-simple';

const compiler= createCompiler({defaultLibLocation:'node_modules/typescript/lib'});

const r: CompileResult = compiler.compile('let x = 3 + 2');

assert.lengthOf(r.diagnostics, 0);

(using assert from chai module)

like image 124
artem Avatar answered Sep 05 '25 03:09

artem