How use namespace on Deno

/* test1.ts */

/// <reference path="./test2.ts" />

namespace Test {
    export const a = 3;
}

/* test2.ts */

/// <reference path="./test1.ts" />

export namespace Test {
    export const b = 5;
        // If i try to use "a", doesn't work
}

/* test3.ts */
/// <reference path="./test1.ts" />
/// <reference path="./test2.ts" />

console.log(Test.a); // "Cannot find name 'Test'."