diff --git a/test/unit/engine_sequencer.js b/test/unit/engine_sequencer.js
index 23ec4c13d..1e000ad36 100644
--- a/test/unit/engine_sequencer.js
+++ b/test/unit/engine_sequencer.js
@@ -1,8 +1,178 @@
 var test = require('tap').test;
 var Sequencer = require('../../src/engine/sequencer');
+var Runtime = require('../../src/engine/runtime');
+var Thread = require('../../src/engine/thread');
+var RenderedTarget = require('../../src/sprites/rendered-target');
+var Sprite = require('../../src/sprites/sprite');
 
 test('spec', function (t) {
     t.type(Sequencer, 'function');
-    // @todo
+    
+    var r = new Runtime();
+    var s = new Sequencer(r);
+
+    t.type(s, 'object');
+    t.ok(s instanceof Sequencer);
+    
+    t.type(s.stepThreads, 'function');
+    t.type(s.stepThread, 'function');
+    t.type(s.stepToBranch, 'function');
+    t.type(s.stepToProcedure, 'function');
+    t.type(s.retireThread, 'function');
+
+    t.end();
+});
+
+var randomString = function () {
+    var top = Math.random().toString(36);
+    return top.substring(7);
+};
+
+var generateBlock = function (id) {
+    var block = {fields: Object,
+        id: id,
+        inputs: {},
+        STEPS: Object,
+        block: 'fakeBlock',
+        name: 'fakeName',
+        next: null,
+        opcode: 'procedures_defnoreturn',
+        mutation: {proccode: 'fakeCode'},
+        parent: null,
+        shadow: false,
+        topLevel: true,
+        x: 0,
+        y: 0
+    };
+    return block;
+};
+
+var generateBlockInput = function (id, next, inp) {
+    var block = {fields: Object,
+        id: id,
+        inputs: {SUBSTACK: {block: inp, name: 'SUBSTACK'}},
+        STEPS: Object,
+        block: 'fakeBlock',
+        name: 'fakeName',
+        next: next,
+        opcode: 'procedures_defnoreturn',
+        mutation: {proccode: 'fakeCode'},
+        parent: null,
+        shadow: false,
+        topLevel: true,
+        x: 0,
+        y: 0
+    };
+    return block;
+};
+
+var generateThread = function (runtime) {
+    var s = new Sprite();
+    var rt = new RenderedTarget(s, runtime);
+    var th = new Thread(randomString());
+    
+    var next = randomString();
+    var inp = randomString();
+    var name = th.topBlock;
+    
+    rt.blocks.createBlock(generateBlockInput(name, next, inp));
+    th.pushStack(name);
+    rt.blocks.createBlock(generateBlock(inp));
+    
+    for (var i = 0; i < 10; i++) {
+        name = next;
+        next = randomString();
+        inp = randomString();
+        
+        rt.blocks.createBlock(generateBlockInput(name, next, inp));
+        th.pushStack(name);
+        rt.blocks.createBlock(generateBlock(inp));
+    }
+    rt.blocks.createBlock(generateBlock(next));
+    th.pushStack(next);
+    th.target = rt;
+    
+    runtime.threads.push(th);
+
+    return th;
+};
+
+test('stepThread', function (t) {
+    var r = new Runtime();
+    var s = new Sequencer(r);
+    var th = generateThread(r);
+    t.notEquals(th.status, Thread.STATUS_DONE);
+    s.stepThread(th);
+    t.strictEquals(th.status, Thread.STATUS_DONE);
+    th = generateThread(r);
+    th.status = Thread.STATUS_YIELD;
+    s.stepThread(th);
+    t.notEquals(th.status, Thread.STATUS_DONE);
+    th.status = Thread.STATUS_PROMISE_WAIT;
+    s.stepThread(th);
+    t.notEquals(th.status, Thread.STATUS_DONE);
+    
+    t.end();
+});
+
+test('stepToBranch', function (t) {
+    var r = new Runtime();
+    var s = new Sequencer(r);
+    var th = generateThread(r);
+    s.stepToBranch(th, 2, false);
+    t.strictEquals(th.peekStack(), null);
+    th.popStack();
+    s.stepToBranch(th, 1, false);
+    t.strictEquals(th.peekStack(), null);
+    th.popStack();
+    th.popStack();
+    s.stepToBranch(th, 1, false);
+    t.notEquals(th.peekStack(), null);
+    
+    t.end();
+});
+
+test('retireThread', function (t) {
+    var r = new Runtime();
+    var s = new Sequencer(r);
+    var th = generateThread(r);
+    t.strictEquals(th.stack.length, 12);
+    s.retireThread(th);
+    t.strictEquals(th.stack.length, 0);
+    t.strictEquals(th.status, Thread.STATUS_DONE);
+    
+    t.end();
+});
+
+test('stepToProcedure', function (t) {
+    var r = new Runtime();
+    var s = new Sequencer(r);
+    var th = generateThread(r);
+    var expectedBlock = th.peekStack();
+    s.stepToProcedure(th, '');
+    t.strictEquals(th.peekStack(), expectedBlock);
+    s.stepToProcedure(th, 'faceCode');
+    t.strictEquals(th.peekStack(), expectedBlock);
+    s.stepToProcedure(th, 'faceCode');
+    th.target.blocks.getBlock(th.stack[th.stack.length - 4]).mutation.proccode = 'othercode';
+    expectedBlock = th.stack[th.stack.length - 4];
+    s.stepToProcedure(th, 'othercode');
+    t.strictEquals(th.peekStack(), expectedBlock);
+    
+    
+    t.end();
+});
+
+test('stepThreads', function (t) {
+    var r = new Runtime();
+    r.currentStepTime = Infinity;
+    var s = new Sequencer(r);
+    t.strictEquals(s.stepThreads().length, 0);
+    generateThread(r);
+    t.strictEquals(r.threads.length, 1);
+    t.strictEquals(s.stepThreads().length, 0);
+    r.threads[0].status = Thread.STATUS_RUNNING;
+    t.strictEquals(s.stepThreads().length, 1);
+    
     t.end();
 });