feat(napi-derive): support const export

examples/napi/__test__/typegen.spec.ts.md

@@ -8,7 +8,8 @@ Generated by [AVA](https://avajs.dev).
 
 > Snapshot 1
 
-    `export function getWords(): Array<string>␊
+    `export const DEFAULT_COST: number␊
+    export function getWords(): Array<string>␊
     export function getNums(): Array<number>␊
     export function sumNums(nums: Array<number>): number␊
     export function readFileAsync(path: string): Promise<Buffer>␊

examples/napi/__test__/values.spec.ts

@@ -3,6 +3,7 @@ import { join } from 'path'
 import test from 'ava'
 
 import {
+  DEFAULT_COST,
   add,
   fibonacci,
   contains,
@@ -48,6 +49,10 @@ import {
   createSymbol,
 } from '../'
 
+test('export const', (t) => {
+  t.is(DEFAULT_COST, 12)
+})
+
 test('number', (t) => {
   t.is(add(1, 2), 3)
   t.is(fibonacci(5), 5)

examples/napi/index.d.ts

@@ -1,3 +1,4 @@
+export const DEFAULT_COST: number
 export function getWords(): Array<string>
 export function getNums(): Array<number>
 export function sumNums(nums: Array<number>): number

examples/napi/src/lib.rs

@@ -3,6 +3,9 @@ extern crate napi_derive;
 #[macro_use]
 extern crate serde_derive;
 
+#[napi]
+pub const DEFAULT_COST: u32 = 12;
+
 mod array;
 mod r#async;
 mod bigint;