How to run Mocha tests in a defined order

Background

I am working on a program in Node.js and writing my test suites in Mocha with Chai and SinonJS. I have core graphics module which controls access to a node-webl context.

Due to how node-webgl works, I only wish to initialize a context once for the entire test run. I have some tests I wish to run prior to the initialization of the core module, like so:

describe('module:core', function () {
    describe('pre-init', function () {
        describe('.isInitialized', function () {
            it('should return false if the module is not initialized', function () {
                expect(core.isInitialized()).to.be.false;
            });
        });
        describe('.getContext', function () {
            it('should error if no context is available', function () {
                expect(function () {
                    core.getContext();
                }).to.throw(/no context/i);
            });
        });
    });
    describe('.init', function () {
        it('should error on an invalid canvas', function () {
            expect(function () {
                core.init(null);
            }).to.throw(/undefined or not an object/i);
            expect(function () {
                core.init({});
            }).to.throw(/missing getcontext/i);
        });
        it('should error if the native context could not be created', function () {
            var stub = sinon.stub(global._canvas, 'getContext').returns(null);
            expect(function () {
                core.init(global._canvas);
            }).to.throw(/returned null/i);
            stub.restore();
        });
        it('should initialize the core module', function () {
            expect(function () {
                core.init(global._canvas);
            }).not.to.throw();
        });
    });
    describe('post-init', function () {
        describe('.isInitialized', function () {
            it('should return true if the module is initialized', function () {
                expect(core.isInitialized()).to.be.true;
            });
        });
        describe('.getContext', function () {
            it('should return the current WebGL context', function () {
                var gl = null;
                expect(function () {
                    gl = core.getContext();
                }).not.to.throw();
                // TODO Figure out if it's actually a WebGL context.
                expect(gl).to.exist;
            });
        });
    });
});

Then I can run the remaining tests.

Problem

When I run this through Mocha, everything is fine since the core test suite is the first thing to be run. My concern is that if anything gets run before the core test suite, then those tests will fail as the core is not initialized yet.

What is the best way to ensure the core test suite is always run first?