Mocha unexpected async behavior

mocha-unexpected-async.js

describe("Outer", function () {
    var promise = null;

    beforeEach(function () {
        setTimeout(function () {
            console.error("Outer beforeEach");
        }, 0);
    });

    describe("Inner A", function () {
        beforeEach(function () {
            console.error("Inner beforeEach A");
        });

        it("Inner A", function () {
            console.error("Inner A");
        });
    });

    describe("Inner B", function () {
        beforeEach(function () {
            console.error("Inner beforeEach B");
        });

        it("Inner B", function () {
            console.error("Inner B");
        });
    });
});

output.txt

Outer beforeEach
Inner beforeEach A
Inner A
Inner beforeEach B
Inner B
Outer beforeEach