TypeScript/tests/cases/conformance/types/never/neverType.ts
Anders Hejlsberg b8e9ecfb1a Add tests
2016-05-23 13:08:15 -07:00

94 lines
1.7 KiB
TypeScript

// @strictNullChecks: true
// @declaration: true
function error(message: string): never {
throw new Error(message);
}
function errorVoid(message: string) {
throw new Error(message);
}
function fail() {
return error("Something failed");
}
function failOrThrow(shouldFail: boolean) {
if (shouldFail) {
return fail();
}
throw new Error();
}
function infiniteLoop1() {
while (true) {
}
}
function infiniteLoop2(): never {
while (true) {
}
}
function move1(direction: "up" | "down") {
switch (direction) {
case "up":
return 1;
case "down":
return -1;
}
return error("Should never get here");
}
function move2(direction: "up" | "down") {
return direction === "up" ? 1 :
direction === "down" ? -1 :
error("Should never get here");
}
function check<T>(x: T | undefined) {
return x || error("Undefined value");
}
class C {
void1() {
throw new Error();
}
void2() {
while (true) {}
}
never1(): never {
throw new Error();
}
never2(): never {
while (true) {}
}
}
function f1(x: string | number) {
if (typeof x === "boolean") {
x; // never
}
}
function f2(x: string | number) {
while (true) {
if (typeof x === "boolean") {
return x; // never
}
}
}
function test(cb: () => string) {
let s = cb();
return s;
}
let errorCallback = () => error("Error callback");
test(() => "hello");
test(() => fail());
test(() => { throw new Error(); })
test(errorCallback);