diff --git a/.travis.yml b/.travis.yml
index f836d9861..091fe53fe 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,9 @@ sudo: false
 cache:
   directories:
   - node_modules
+before_install:
+# Install the most up to date scratch-* dependencies
+- rm -rf node_modules/scratch-*
 after_script:
 - |
   # RELEASE_BRANCHES and NPM_TOKEN defined in Travis settings panel
diff --git a/playground/index.html b/playground/index.html
index 173ab844e..804d31f8e 100644
--- a/playground/index.html
+++ b/playground/index.html
@@ -437,7 +437,7 @@
       <category name="Data" colour="#FF8C1A" custom="VARIABLE">
       </category>
       <category name="Lists" colour="#FF8C1A">
-        <block type="data_list"></block>
+        <block type="data_listcontents"></block>
         <block type="data_addtolist">
           <value name="ITEM">
             <shadow type="text">
diff --git a/src/blocks/scratch3_motion.js b/src/blocks/scratch3_motion.js
index 10679750d..8b8e7356e 100644
--- a/src/blocks/scratch3_motion.js
+++ b/src/blocks/scratch3_motion.js
@@ -22,6 +22,7 @@ Scratch3MotionBlocks.prototype.getPrimitives = function() {
         'motion_turnleft': this.turnLeft,
         'motion_pointindirection': this.pointInDirection,
         'motion_glidesecstoxy': this.glide,
+        'motion_setrotationstyle': this.setRotationStyle,
         'motion_changexby': this.changeX,
         'motion_setx': this.setX,
         'motion_changeyby': this.changeY,
@@ -96,6 +97,10 @@ Scratch3MotionBlocks.prototype.glide = function (args, util) {
     }
 };
 
+Scratch3MotionBlocks.prototype.setRotationStyle = function (args, util) {
+    util.target.setRotationStyle(args.STYLE);
+};
+
 Scratch3MotionBlocks.prototype.changeX = function (args, util) {
     var dx = Cast.toNumber(args.DX);
     util.target.setXY(util.target.x + dx, util.target.y);
diff --git a/src/blocks/scratch3_procedures.js b/src/blocks/scratch3_procedures.js
new file mode 100644
index 000000000..8d43c4c92
--- /dev/null
+++ b/src/blocks/scratch3_procedures.js
@@ -0,0 +1,32 @@
+function Scratch3ProcedureBlocks(runtime) {
+    /**
+     * The runtime instantiating this block package.
+     * @type {Runtime}
+     */
+    this.runtime = runtime;
+}
+
+/**
+ * Retrieve the block primitives implemented by this package.
+ * @return {Object.<string, Function>} Mapping of opcode to Function.
+ */
+Scratch3ProcedureBlocks.prototype.getPrimitives = function() {
+    return {
+        'procedures_defnoreturn': this.defNoReturn,
+        'procedures_callnoreturn': this.callNoReturn
+    };
+};
+
+Scratch3ProcedureBlocks.prototype.defNoReturn = function () {
+    // No-op: execute the blocks.
+};
+
+Scratch3ProcedureBlocks.prototype.callNoReturn = function (args, util) {
+    if (!util.stackFrame.executed) {
+        var procedureName = args.mutation.name;
+        util.stackFrame.executed = true;
+        util.startProcedure(procedureName);
+    }
+};
+
+module.exports = Scratch3ProcedureBlocks;
diff --git a/src/engine/adapter.js b/src/engine/adapter.js
index 26f52be90..327aae5e3 100644
--- a/src/engine/adapter.js
+++ b/src/engine/adapter.js
@@ -1,3 +1,4 @@
+var mutationAdapter = require('./mutation-adapter');
 var html = require('htmlparser2');
 
 /**
@@ -138,6 +139,9 @@ function domToBlock (blockDOM, blocks, isTopBlock, parent) {
             // Link next block to this block.
             block.next = childBlockNode.attribs.id;
             break;
+        case 'mutation':
+            block.mutation = mutationAdapter(xmlChild);
+            break;
         }
     }
 }
diff --git a/src/engine/blocks.js b/src/engine/blocks.js
index 99f52477d..f96c916ad 100644
--- a/src/engine/blocks.js
+++ b/src/engine/blocks.js
@@ -1,4 +1,5 @@
 var adapter = require('./adapter');
+var mutationAdapter = require('./mutation-adapter');
 var xmlEscape = require('../util/xml-escape');
 
 /**
@@ -116,6 +117,16 @@ Blocks.prototype.getInputs = function (id) {
     return inputs;
 };
 
+/**
+ * Get mutation data for a block.
+ * @param {?string} id ID of block to query.
+ * @return {!Object} Mutation for the block.
+ */
+Blocks.prototype.getMutation = function (id) {
+    if (typeof this._blocks[id] === 'undefined') return null;
+    return this._blocks[id].mutation;
+};
+
 /**
  * Get the top-level script for a given block.
  * @param {?string} id ID of block to query.
@@ -130,6 +141,23 @@ Blocks.prototype.getTopLevelScript = function (id) {
     return block.id;
 };
 
+/**
+ * Get the procedure definition for a given name.
+ * @param {?string} name Name of procedure to query.
+ * @return {?string} ID of procedure definition.
+ */
+Blocks.prototype.getProcedureDefinition = function (name) {
+    for (var id in this._blocks) {
+        var block = this._blocks[id];
+        if ((block.opcode == 'procedures_defnoreturn' ||
+            block.opcode == 'procedures_defreturn') &&
+            block.fields['NAME'].value == name) {
+            return id;
+        }
+    }
+    return null;
+};
+
 // ---------------------------------------------------------------------
 
 /**
@@ -226,12 +254,16 @@ Blocks.prototype.createBlock = function (block, opt_isFlyoutBlock) {
  */
 Blocks.prototype.changeBlock = function (args) {
     // Validate
-    if (args.element !== 'field') return;
+    if (args.element !== 'field' && args.element !== 'mutation') return;
     if (typeof this._blocks[args.id] === 'undefined') return;
-    if (typeof this._blocks[args.id].fields[args.name] === 'undefined') return;
 
-    // Update block value
-    this._blocks[args.id].fields[args.name].value = args.value;
+    if (args.element == 'field') {
+        // Update block value
+        if (!this._blocks[args.id].fields[args.name]) return;
+        this._blocks[args.id].fields[args.name].value = args.value;
+    } else if (args.element == 'mutation') {
+        this._blocks[args.id].mutation = mutationAdapter(args.value);
+    }
 };
 
 /**
@@ -355,6 +387,10 @@ Blocks.prototype.blockToXML = function (blockId) {
         ' type="' + block.opcode + '"' +
         xy +
         '>';
+    // Add any mutation. Must come before inputs.
+    if (block.mutation) {
+        xmlString += this.mutationToXML(block.mutation);
+    }
     // Add any inputs on this block.
     for (var input in block.inputs) {
         var blockInput = block.inputs[input];
@@ -389,6 +425,25 @@ Blocks.prototype.blockToXML = function (blockId) {
     return xmlString;
 };
 
+/**
+ * Recursively encode a mutation object to XML.
+ * @param {!Object} mutation Object representing a mutation.
+ * @return {string} XML string representing a mutation.
+ */
+Blocks.prototype.mutationToXML = function (mutation) {
+    var mutationString = '<' + mutation.tagName;
+    for (var prop in mutation) {
+        if (prop == 'children' || prop == 'tagName') continue;
+        mutationString += ' ' + prop + '="' + mutation[prop] + '"';
+    }
+    mutationString += '>';
+    for (var i = 0; i < mutation.children.length; i++) {
+        mutationString += this.mutationToXML(mutation.children[i]);
+    }
+    mutationString += '</' + mutation.tagName + '>';
+    return mutationString;
+};
+
 // ---------------------------------------------------------------------
 
 /**
diff --git a/src/engine/execute.js b/src/engine/execute.js
index 29116d5e5..59b4a3cbf 100644
--- a/src/engine/execute.js
+++ b/src/engine/execute.js
@@ -132,6 +132,12 @@ var execute = function (sequencer, thread) {
         argValues[inputName] = currentStackFrame.reported[inputName];
     }
 
+    // Add any mutation to args (e.g., for procedures).
+    var mutation = target.blocks.getMutation(currentBlockId);
+    if (mutation) {
+        argValues.mutation = mutation;
+    }
+
     // If we've gotten this far, all of the input blocks are evaluated,
     // and `argValues` is fully populated. So, execute the block primitive.
     // First, clear `currentStackFrame.reported`, so any subsequent execution
@@ -155,6 +161,9 @@ var execute = function (sequencer, thread) {
         startBranch: function (branchNum) {
             sequencer.stepToBranch(thread, branchNum);
         },
+        startProcedure: function (procedureName) {
+            sequencer.stepToProcedure(thread, procedureName);
+        },
         startHats: function(requestedHat, opt_matchFields, opt_target) {
             return (
                 runtime.startHats(requestedHat, opt_matchFields, opt_target)
diff --git a/src/engine/mutation-adapter.js b/src/engine/mutation-adapter.js
new file mode 100644
index 000000000..12dc123e1
--- /dev/null
+++ b/src/engine/mutation-adapter.js
@@ -0,0 +1,39 @@
+var html = require('htmlparser2');
+
+/**
+ * Adapter between mutator XML or DOM and block representation which can be
+ * used by the Scratch runtime.
+ * @param {(Object|string)} mutation Mutation XML string or DOM.
+ * @return {Object} Object representing the mutation.
+ */
+module.exports = function (mutation) {
+    var mutationParsed;
+    // Check if the mutation is already parsed; if not, parse it.
+    if (typeof mutation === 'object') {
+        mutationParsed = mutation;
+    } else {
+        mutationParsed = html.parseDOM(mutation)[0];
+    }
+    return mutatorTagToObject(mutationParsed);
+};
+
+/**
+ * Convert a part of a mutation DOM to a mutation VM object, recursively.
+ * @param {Object} dom DOM object for mutation tag.
+ * @return {Object} Object representing useful parts of this mutation.
+ */
+function mutatorTagToObject (dom) {
+    var obj = Object.create(null);
+    obj.tagName = dom.name;
+    obj.children = [];
+    for (var prop in dom.attribs) {
+        if (prop == 'xmlns') continue;
+        obj[prop] = dom.attribs[prop];
+    }
+    for (var i = 0; i < dom.children.length; i++) {
+        obj.children.push(
+            mutatorTagToObject(dom.children[i])
+        );
+    }
+    return obj;
+}
diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 2792dab2b..bad95bdf7 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -16,7 +16,8 @@ var defaultBlockPackages = {
     'scratch3_operators': require('../blocks/scratch3_operators'),
     'scratch3_sound': require('../blocks/scratch3_sound'),
     'scratch3_sensing': require('../blocks/scratch3_sensing'),
-    'scratch3_data': require('../blocks/scratch3_data')
+    'scratch3_data': require('../blocks/scratch3_data'),
+    'scratch3_procedures': require('../blocks/scratch3_procedures')
 };
 
 /**
diff --git a/src/engine/sequencer.js b/src/engine/sequencer.js
index 690ab61a7..85575c804 100644
--- a/src/engine/sequencer.js
+++ b/src/engine/sequencer.js
@@ -124,6 +124,16 @@ Sequencer.prototype.stepToBranch = function (thread, branchNum) {
     }
 };
 
+/**
+ * Step a procedure.
+ * @param {!Thread} thread Thread object to step to procedure.
+ * @param {!string} procedureName Name of procedure defined in this target.
+ */
+Sequencer.prototype.stepToProcedure = function (thread, procedureName) {
+    var definition = thread.target.blocks.getProcedureDefinition(procedureName);
+    thread.pushStack(definition);
+};
+
 /**
  * Step a thread into an input reporter, and manage its status appropriately.
  * @param {!Thread} thread Thread object to step to reporter.
diff --git a/src/import/sb2import.js b/src/import/sb2import.js
index 5d383cc74..50911c83e 100644
--- a/src/import/sb2import.js
+++ b/src/import/sb2import.js
@@ -6,6 +6,7 @@
  */
 
 var Blocks = require('../engine/blocks');
+var Clone = require('../sprites/clone');
 var Sprite = require('../sprites/sprite');
 var Color = require('../util/color.js');
 var uid = require('../util/uid');
@@ -123,7 +124,16 @@ function parseScratchObject (object, runtime, topLevel) {
         target.visible = object.visible;
     }
     if (object.hasOwnProperty('currentCostumeIndex')) {
-        target.currentCostume = object.currentCostumeIndex;
+        target.currentCostume = Math.round(object.currentCostumeIndex);
+    }
+    if (object.hasOwnProperty('rotationStyle')) {
+        if (object.rotationStyle == 'none') {
+            target.rotationStyle = Clone.ROTATION_STYLE_NONE;
+        } else if (object.rotationStyle == 'leftRight') {
+            target.rotationStyle = Clone.ROTATION_STYLE_LEFT_RIGHT;
+        } else if (object.rotationStyle == 'normal') {
+            target.rotationStyle = Clone.ROTATION_STYLE_ALL_AROUND;
+        }
     }
     target.isStage = topLevel;
     target.updateAllDrawableProperties();
@@ -332,6 +342,14 @@ function parseBlock (sb2block) {
             };
         }
     }
+    // Special cases to generate mutations.
+    if (oldOpcode == 'call') {
+        activeBlock.mutation = {
+            tagName: 'mutation',
+            children: [],
+            name: sb2block[1]
+        };
+    }
     return activeBlock;
 }
 
diff --git a/src/import/sb2specmap.js b/src/import/sb2specmap.js
index 693d82f81..76e9683e1 100644
--- a/src/import/sb2specmap.js
+++ b/src/import/sb2specmap.js
@@ -1374,15 +1374,20 @@ var specMap = {
         ]
     },
     'procDef':{
-        'opcode':'proc_def',
-        'argMap':[]
+        'opcode':'procedures_defnoreturn',
+        'argMap':[
+            {
+                'type':'field',
+                'fieldName':'NAME'
+            }
+        ]
     },
     'getParam':{
         'opcode':'proc_param',
         'argMap':[]
     },
     'call':{
-        'opcode':'proc_call',
+        'opcode':'procedures_callnoreturn',
         'argMap':[]
     }
 };
diff --git a/src/sprites/clone.js b/src/sprites/clone.js
index 5b3d2def2..c1b3d42cf 100644
--- a/src/sprites/clone.js
+++ b/src/sprites/clone.js
@@ -29,6 +29,20 @@ function Clone(sprite, runtime) {
      * @type {?Number}
      */
     this.drawableID = null;
+
+    /**
+     * Map of current graphic effect values.
+     * @type {!Object.<string, number>}
+     */
+    this.effects = {
+        'color': 0,
+        'fisheye': 0,
+        'whirl': 0,
+        'pixelate': 0,
+        'mosaic': 0,
+        'brightness': 0,
+        'ghost': 0
+    };
 }
 util.inherits(Clone, Target);
 
@@ -38,7 +52,6 @@ util.inherits(Clone, Target);
 Clone.prototype.initDrawable = function () {
     if (this.renderer) {
         this.drawableID = this.renderer.createDrawable();
-        this.updateAllDrawableProperties();
     }
     // If we're a clone, start the hats.
     if (!this.isOriginal) {
@@ -99,18 +112,29 @@ Clone.prototype.size = 100;
 Clone.prototype.currentCostume = 0;
 
 /**
- * Map of current graphic effect values.
- * @type {!Object.<string, number>}
+ * Rotation style for "all around"/spinning.
+ * @enum
  */
-Clone.prototype.effects = {
-    'color': 0,
-    'fisheye': 0,
-    'whirl': 0,
-    'pixelate': 0,
-    'mosaic': 0,
-    'brightness': 0,
-    'ghost': 0
-};
+Clone.ROTATION_STYLE_ALL_AROUND = 'all around';
+
+/**
+ * Rotation style for "left-right"/flipping.
+ * @enum
+ */
+Clone.ROTATION_STYLE_LEFT_RIGHT = 'left-right';
+
+/**
+ * Rotation style for "no rotation."
+ * @enum
+ */
+Clone.ROTATION_STYLE_NONE = 'don\'t rotate';
+
+/**
+ * Current rotation style.
+ * @type {!string}
+ */
+Clone.prototype.rotationStyle = Clone.ROTATION_STYLE_ALL_AROUND;
+
 // End clone-level properties.
 
 /**
@@ -131,6 +155,26 @@ Clone.prototype.setXY = function (x, y) {
     }
 };
 
+/**
+ * Get the rendered direction and scale, after applying rotation style.
+ * @return {Object<string, number>} Direction and scale to render.
+ */
+Clone.prototype._getRenderedDirectionAndScale = function () {
+    // Default: no changes to `this.direction` or `this.scale`.
+    var finalDirection = this.direction;
+    var finalScale = [this.size, this.size];
+    if (this.rotationStyle == Clone.ROTATION_STYLE_NONE) {
+        // Force rendered direction to be 90.
+        finalDirection = 90;
+    } else if (this.rotationStyle === Clone.ROTATION_STYLE_LEFT_RIGHT) {
+        // Force rendered direction to be 90, and flip drawable if needed.
+        finalDirection = 90;
+        var scaleFlip = (this.direction < 0) ? -1 : 1;
+        finalScale = [scaleFlip * this.size, this.size];
+    }
+    return {direction: finalDirection, scale: finalScale};
+};
+
 /**
  * Set the direction of a clone.
  * @param {!number} direction New direction of clone.
@@ -142,8 +186,10 @@ Clone.prototype.setDirection = function (direction) {
     // Keep direction between -179 and +180.
     this.direction = MathUtil.wrapClamp(direction, -179, 180);
     if (this.renderer) {
+        var renderedDirectionScale = this._getRenderedDirectionAndScale();
         this.renderer.updateDrawableProperties(this.drawableID, {
-            direction: this.direction
+            direction: renderedDirectionScale.direction,
+            scale: renderedDirectionScale.scale
         });
     }
 };
@@ -192,8 +238,10 @@ Clone.prototype.setSize = function (size) {
     // Keep size between 5% and 535%.
     this.size = MathUtil.clamp(size, 5, 535);
     if (this.renderer) {
+        var renderedDirectionScale = this._getRenderedDirectionAndScale();
         this.renderer.updateDrawableProperties(this.drawableID, {
-            scale: [this.size, this.size]
+            direction: renderedDirectionScale.direction,
+            scale: renderedDirectionScale.scale
         });
     }
 };
@@ -231,6 +279,7 @@ Clone.prototype.clearEffects = function () {
  */
 Clone.prototype.setCostume = function (index) {
     // Keep the costume index within possible values.
+    index = Math.round(index);
     this.currentCostume = MathUtil.wrapClamp(
         index, 0, this.sprite.costumes.length - 1
     );
@@ -241,6 +290,27 @@ Clone.prototype.setCostume = function (index) {
     }
 };
 
+/**
+ * Update the rotation style for this clone.
+ * @param {!string} rotationStyle New rotation style.
+ */
+Clone.prototype.setRotationStyle = function (rotationStyle) {
+    if (rotationStyle == Clone.ROTATION_STYLE_NONE) {
+        this.rotationStyle = Clone.ROTATION_STYLE_NONE;
+    } else if (rotationStyle == Clone.ROTATION_STYLE_ALL_AROUND) {
+        this.rotationStyle = Clone.ROTATION_STYLE_ALL_AROUND;
+    } else if (rotationStyle == Clone.ROTATION_STYLE_LEFT_RIGHT) {
+        this.rotationStyle = Clone.ROTATION_STYLE_LEFT_RIGHT;
+    }
+    if (this.renderer) {
+        var renderedDirectionScale = this._getRenderedDirectionAndScale();
+        this.renderer.updateDrawableProperties(this.drawableID, {
+            direction: renderedDirectionScale.direction,
+            scale: renderedDirectionScale.scale
+        });
+    }
+};
+
 /**
  * Get a costume index of this clone, by name of the costume.
  * @param {?string} costumeName Name of a costume.
@@ -275,10 +345,11 @@ Clone.prototype.getSoundIndexByName = function (soundName) {
  */
 Clone.prototype.updateAllDrawableProperties = function () {
     if (this.renderer) {
+        var renderedDirectionScale = this._getRenderedDirectionAndScale();
         this.renderer.updateDrawableProperties(this.drawableID, {
             position: [this.x, this.y],
-            direction: this.direction,
-            scale: [this.size, this.size],
+            direction: renderedDirectionScale.direction,
+            scale: renderedDirectionScale.scale,
             visible: this.visible,
             skin: this.sprite.costumes[this.currentCostume].skin
         });
@@ -340,6 +411,7 @@ Clone.prototype.makeClone = function () {
     newClone.visible = this.visible;
     newClone.size = this.size;
     newClone.currentCostume = this.currentCostume;
+    newClone.rotationStyle = this.rotationStyle;
     newClone.effects = JSON.parse(JSON.stringify(this.effects));
     newClone.variables = JSON.parse(JSON.stringify(this.variables));
     newClone.lists = JSON.parse(JSON.stringify(this.lists));
diff --git a/src/sprites/sprite.js b/src/sprites/sprite.js
index cfa8de90d..53f16e286 100644
--- a/src/sprites/sprite.js
+++ b/src/sprites/sprite.js
@@ -54,7 +54,6 @@ Sprite.prototype.createClone = function () {
     this.clones.push(newClone);
     if (newClone.isOriginal) {
         newClone.initDrawable();
-        newClone.updateAllDrawableProperties();
     }
     return newClone;
 };
diff --git a/test/unit/adapter.js b/test/unit/engine_adapter.js
similarity index 100%
rename from test/unit/adapter.js
rename to test/unit/engine_adapter.js
diff --git a/test/unit/blocks.js b/test/unit/engine_blocks.js
similarity index 100%
rename from test/unit/blocks.js
rename to test/unit/engine_blocks.js
diff --git a/test/unit/runtime.js b/test/unit/engine_runtime.js
similarity index 100%
rename from test/unit/runtime.js
rename to test/unit/engine_runtime.js
diff --git a/test/unit/sequencer.js b/test/unit/engine_sequencer.js
similarity index 100%
rename from test/unit/sequencer.js
rename to test/unit/engine_sequencer.js
diff --git a/test/unit/thread.js b/test/unit/engine_thread.js
similarity index 100%
rename from test/unit/thread.js
rename to test/unit/engine_thread.js
diff --git a/test/unit/sprites_clone.js b/test/unit/sprites_clone.js
new file mode 100644
index 000000000..246e1b955
--- /dev/null
+++ b/test/unit/sprites_clone.js
@@ -0,0 +1,13 @@
+var test = require('tap').test;
+var Clone = require('../../src/sprites/clone');
+var Sprite = require('../../src/sprites/sprite');
+
+test('clone effects', function (t) {
+    // Create two clones and ensure they have different graphic effect objects.
+    // Regression test for Github issue #224
+    var spr = new Sprite();
+    var a = new Clone(spr, null);
+    var b = new Clone(spr, null);
+    t.ok(a.effects !== b.effects);
+    t.end();
+});
diff --git a/test/unit/util_cast.js b/test/unit/util_cast.js
new file mode 100644
index 000000000..1d372213e
--- /dev/null
+++ b/test/unit/util_cast.js
@@ -0,0 +1,179 @@
+var test = require('tap').test;
+var cast = require('../../src/util/cast');
+
+test('toNumber', function (t) {
+    // Numeric
+    t.strictEqual(cast.toNumber(0), 0);
+    t.strictEqual(cast.toNumber(1), 1);
+    t.strictEqual(cast.toNumber(3.14), 3.14);
+
+    // String
+    t.strictEqual(cast.toNumber('0'), 0);
+    t.strictEqual(cast.toNumber('1'), 1);
+    t.strictEqual(cast.toNumber('3.14'), 3.14);
+    t.strictEqual(cast.toNumber('0.1e10'), 1000000000);
+    t.strictEqual(cast.toNumber('foobar'), 0);
+
+    // Boolean
+    t.strictEqual(cast.toNumber(true), 1);
+    t.strictEqual(cast.toNumber(false), 0);
+    t.strictEqual(cast.toNumber('true'), 0);
+    t.strictEqual(cast.toNumber('false'), 0);
+
+    // Undefined & object
+    t.strictEqual(cast.toNumber(undefined), 0);
+    t.strictEqual(cast.toNumber({}), 0);
+    t.strictEqual(cast.toNumber(NaN), 0);
+    t.end();
+});
+
+test('toBoolean', function (t) {
+    // Numeric
+    t.strictEqual(cast.toBoolean(0), false);
+    t.strictEqual(cast.toBoolean(1), true);
+    t.strictEqual(cast.toBoolean(3.14), true);
+
+    // String
+    t.strictEqual(cast.toBoolean('0'), false);
+    t.strictEqual(cast.toBoolean('1'), true);
+    t.strictEqual(cast.toBoolean('3.14'), true);
+    t.strictEqual(cast.toBoolean('0.1e10'), true);
+    t.strictEqual(cast.toBoolean('foobar'), true);
+
+    // Boolean
+    t.strictEqual(cast.toBoolean(true), true);
+    t.strictEqual(cast.toBoolean(false), false);
+
+    // Undefined & object
+    t.strictEqual(cast.toBoolean(undefined), false);
+    t.strictEqual(cast.toBoolean({}), true);
+    t.end();
+});
+
+test('toString', function (t) {
+    // Numeric
+    t.strictEqual(cast.toString(0), '0');
+    t.strictEqual(cast.toString(1), '1');
+    t.strictEqual(cast.toString(3.14), '3.14');
+
+    // String
+    t.strictEqual(cast.toString('0'), '0');
+    t.strictEqual(cast.toString('1'), '1');
+    t.strictEqual(cast.toString('3.14'), '3.14');
+    t.strictEqual(cast.toString('0.1e10'), '0.1e10');
+    t.strictEqual(cast.toString('foobar'), 'foobar');
+
+    // Boolean
+    t.strictEqual(cast.toString(true), 'true');
+    t.strictEqual(cast.toString(false), 'false');
+
+    // Undefined & object
+    t.strictEqual(cast.toString(undefined), 'undefined');
+    t.strictEqual(cast.toString({}), '[object Object]');
+    t.end();
+});
+
+test('toRbgColorList', function (t) {
+    // Hex (minimal, see "color" util tests)
+    t.deepEqual(cast.toRgbColorList('#000'), [0,0,0]);
+    t.deepEqual(cast.toRgbColorList('#000000'), [0,0,0]);
+    t.deepEqual(cast.toRgbColorList('#fff'), [255,255,255]);
+    t.deepEqual(cast.toRgbColorList('#ffffff'), [255,255,255]);
+
+    // Decimal (minimal, see "color" util tests)
+    t.deepEqual(cast.toRgbColorList(0), [0,0,0]);
+    t.deepEqual(cast.toRgbColorList(1), [0,0,1]);
+    t.deepEqual(cast.toRgbColorList(16777215), [255,255,255]);
+
+    // Malformed
+    t.deepEqual(cast.toRgbColorList('ffffff'), [0,0,0]);
+    t.deepEqual(cast.toRgbColorList('foobar'), [0,0,0]);
+    t.end();
+});
+
+test('compare', function (t) {
+    // Numeric
+    t.strictEqual(cast.compare(0, 0), 0);
+    t.strictEqual(cast.compare(1, 0), 1);
+    t.strictEqual(cast.compare(0, 1), -1);
+    t.strictEqual(cast.compare(1, 1), 0);
+
+    // String
+    t.strictEqual(cast.compare('0', '0'), 0);
+    t.strictEqual(cast.compare('0.1e10', '1000000000'), 0);
+    t.strictEqual(cast.compare('foobar', 'FOOBAR'), 0);
+    t.ok(cast.compare('dog', 'cat') > 0);
+
+    // Boolean
+    t.strictEqual(cast.compare(true, true), 0);
+    t.strictEqual(cast.compare(true, false), 1);
+    t.strictEqual(cast.compare(false, true), -1);
+    t.strictEqual(cast.compare(true, true), 0);
+
+    // Undefined & object
+    t.strictEqual(cast.compare(undefined, undefined), 0);
+    t.strictEqual(cast.compare(undefined, 'undefined'), 0);
+    t.strictEqual(cast.compare({}, {}), 0);
+    t.strictEqual(cast.compare({}, '[object Object]'), 0);
+    t.end();
+});
+
+test('isInt', function (t) {
+    // Numeric
+    t.strictEqual(cast.isInt(0), true);
+    t.strictEqual(cast.isInt(1), true);
+    t.strictEqual(cast.isInt(0.0), true);
+    t.strictEqual(cast.isInt(3.14), false);
+    t.strictEqual(cast.isInt(NaN), true);
+
+    // String
+    t.strictEqual(cast.isInt('0'), true);
+    t.strictEqual(cast.isInt('1'), true);
+    t.strictEqual(cast.isInt('0.0'), false);
+    t.strictEqual(cast.isInt('0.1e10'), false);
+    t.strictEqual(cast.isInt('3.14'), false);
+
+    // Boolean
+    t.strictEqual(cast.isInt(true), true);
+    t.strictEqual(cast.isInt(false), true);
+
+    // Undefined & object
+    t.strictEqual(cast.isInt(undefined), false);
+    t.strictEqual(cast.isInt({}), false);
+    t.end();
+});
+
+test('toListIndex', function (t) {
+    var list = [0,1,2,3,4,5];
+    var empty = [];
+
+    // Valid
+    t.strictEqual(cast.toListIndex(1, list.length), 1);
+    t.strictEqual(cast.toListIndex(6, list.length), 6);
+
+    // Invalid
+    t.strictEqual(cast.toListIndex(-1, list.length), cast.LIST_INVALID);
+    t.strictEqual(cast.toListIndex(0.1, list.length), cast.LIST_INVALID);
+    t.strictEqual(cast.toListIndex(0, list.length), cast.LIST_INVALID);
+    t.strictEqual(cast.toListIndex(7, list.length), cast.LIST_INVALID);
+
+    // "all"
+    t.strictEqual(cast.toListIndex('all', list.length), cast.LIST_ALL);
+
+    // "last"
+    t.strictEqual(cast.toListIndex('last', list.length), list.length);
+    t.strictEqual(cast.toListIndex('last', empty.length), cast.LIST_INVALID);
+
+    // "random"
+    var random = cast.toListIndex('random', list.length);
+    t.ok(random <= list.length);
+    t.ok(random > 0);
+    t.strictEqual(cast.toListIndex('random', empty.length), cast.LIST_INVALID);
+
+    // "any" (alias for "random")
+    var any = cast.toListIndex('any', list.length);
+    t.ok(any <= list.length);
+    t.ok(any > 0);
+    t.strictEqual(cast.toListIndex('any', empty.length), cast.LIST_INVALID);
+    t.end();
+});
diff --git a/test/unit/util_color.js b/test/unit/util_color.js
new file mode 100644
index 000000000..ba7fa059c
--- /dev/null
+++ b/test/unit/util_color.js
@@ -0,0 +1,62 @@
+var test = require('tap').test;
+var color = require('../../src/util/color');
+
+test('decimalToHex', function (t) {
+    t.strictEqual(color.decimalToHex(0), '#000000');
+    t.strictEqual(color.decimalToHex(1), '#000001');
+    t.strictEqual(color.decimalToHex(16777215), '#ffffff');
+    t.strictEqual(color.decimalToHex(-16777215), '#000001');
+    t.strictEqual(color.decimalToHex(99999999), '#5f5e0ff');
+    t.end();
+});
+
+test('decimalToRgb', function (t) {
+    t.deepEqual(color.decimalToRgb(0), {r:0,g:0,b:0});
+    t.deepEqual(color.decimalToRgb(1), {r:0,g:0,b:1});
+    t.deepEqual(color.decimalToRgb(16777215), {r:255,g:255,b:255});
+    t.deepEqual(color.decimalToRgb(-16777215), {r:0,g:0,b:1});
+    t.deepEqual(color.decimalToRgb(99999999), {r:245,g:224,b:255});
+    t.end();
+});
+
+test('hexToRgb', function (t) {
+    t.deepEqual(color.hexToRgb('#000'), {r:0,g:0,b:0});
+    t.deepEqual(color.hexToRgb('#000000'), {r:0,g:0,b:0});
+    t.deepEqual(color.hexToRgb('#fff'), {r:255,g:255,b:255});
+    t.deepEqual(color.hexToRgb('#ffffff'), {r:255,g:255,b:255});
+    t.deepEqual(color.hexToRgb('#0fa'), {r:0,g:255,b:170});
+    t.deepEqual(color.hexToRgb('#00ffaa'), {r:0,g:255,b:170});
+
+    t.deepEqual(color.hexToRgb('000'), {r:0,g:0,b:0});
+    t.deepEqual(color.hexToRgb('fff'), {r:255,g:255,b:255});
+    t.deepEqual(color.hexToRgb('00ffaa'), {r:0,g:255,b:170});
+
+    t.deepEqual(color.hexToRgb('0'), null);
+    t.deepEqual(color.hexToRgb('hello world'), null);
+
+    t.end();
+});
+
+test('rgbToHex', function (t) {
+    t.strictEqual(color.rgbToHex({r:0,g:0,b:0}), '#000000');
+    t.strictEqual(color.rgbToHex({r:255,g:255,b:255}), '#ffffff');
+    t.strictEqual(color.rgbToHex({r:0,g:255,b:170}), '#00ffaa');
+    t.end();
+});
+
+test('rgbToDecimal', function (t) {
+    t.strictEqual(color.rgbToDecimal({r:0,g:0,b:0}), 0);
+    t.strictEqual(color.rgbToDecimal({r:255,g:255,b:255}), 16777215);
+    t.strictEqual(color.rgbToDecimal({r:0,g:255,b:170}), 65450);
+    t.end();
+});
+
+test('hexToDecimal', function (t) {
+    t.strictEqual(color.hexToDecimal('#000'), 0);
+    t.strictEqual(color.hexToDecimal('#000000'), 0);
+    t.strictEqual(color.hexToDecimal('#fff'), 16777215);
+    t.strictEqual(color.hexToDecimal('#ffffff'), 16777215);
+    t.strictEqual(color.hexToDecimal('#0fa'), 65450);
+    t.strictEqual(color.hexToDecimal('#00ffaa'), 65450);
+    t.end();
+});
diff --git a/test/unit/util_math.js b/test/unit/util_math.js
new file mode 100644
index 000000000..b282e90cc
--- /dev/null
+++ b/test/unit/util_math.js
@@ -0,0 +1,37 @@
+var test = require('tap').test;
+var math = require('../../src/util/math-util');
+
+test('degToRad', function (t) {
+    // @todo This is incorrect
+    t.strictEqual(math.degToRad(0), 1.5707963267948966);
+    t.strictEqual(math.degToRad(1), 1.5533430342749535);
+    t.strictEqual(math.degToRad(180), -1.5707963267948966);
+    t.strictEqual(math.degToRad(360), -4.71238898038469);
+    t.strictEqual(math.degToRad(720), -10.995574287564276);
+    t.end();
+});
+
+test('radToDeg', function (t) {
+    t.strictEqual(math.radToDeg(0), 0);
+    t.strictEqual(math.radToDeg(1), 57.29577951308232);
+    t.strictEqual(math.radToDeg(180), 10313.240312354817);
+    t.strictEqual(math.radToDeg(360), 20626.480624709635);
+    t.strictEqual(math.radToDeg(720), 41252.96124941927);
+    t.end();
+});
+
+test('clamp', function (t) {
+    t.strictEqual(math.clamp(0, 0, 10), 0);
+    t.strictEqual(math.clamp(1, 0, 10), 1);
+    t.strictEqual(math.clamp(-10, 0, 10), 0);
+    t.strictEqual(math.clamp(100, 0, 10), 10);
+    t.end();
+});
+
+test('wrapClamp', function (t) {
+    t.strictEqual(math.wrapClamp(0, 0, 10), 0);
+    t.strictEqual(math.wrapClamp(1, 0, 10), 1);
+    t.strictEqual(math.wrapClamp(-10, 0, 10), 1);
+    t.strictEqual(math.wrapClamp(100, 0, 10), 1);
+    t.end();
+});
diff --git a/test/unit/timer.js b/test/unit/util_timer.js
similarity index 100%
rename from test/unit/timer.js
rename to test/unit/util_timer.js
diff --git a/test/unit/util_xml.js b/test/unit/util_xml.js
new file mode 100644
index 000000000..1906a2ab6
--- /dev/null
+++ b/test/unit/util_xml.js
@@ -0,0 +1,9 @@
+var test = require('tap').test;
+var xml = require('../../src/util/xml-escape');
+
+test('escape', function (t) {
+    var input = '<foo bar="he & llo \'"></foo>';
+    var output = '&lt;foo bar=&quot;he &amp; llo &apos;&quot;&gt;&lt;/foo&gt;';
+    t.strictEqual(xml(input), output);
+    t.end();
+});