diff --git a/lib/utils/cssSelector.js b/lib/utils/cssSelector.js
index 82c62c8..1260894 100644
--- a/lib/utils/cssSelector.js
+++ b/lib/utils/cssSelector.js
@@ -10,6 +10,20 @@ const inList = (list = [], selector = '') => {
   });
 };
 
+const sanitizeForEmmet = (selectors = '') => {
+  if (!isString(selectors)) {
+    return false;
+  }
+
+  return selectors.trim()
+    .replace(/\ > \ /g, ' ')
+    .replace(/>/g, ' ')
+    .replace(/\ \ \ \ /g, ' ')
+    .replace(/\ \ \ /g, ' ')
+    .replace(/\ \ /g, ' ')
+    .replace(/\ /g, ' > ');
+};
+
 const split = (selector = '') => {
   if (!isString(selector)) {
     return false;
@@ -20,5 +34,6 @@ const split = (selector = '') => {
 
 module.exports = {
   inList,
+  sanitizeForEmmet,
   split,
 };
diff --git a/lib/utils/isString.js b/lib/utils/isString.js
index baa5d5a..9189d22 100644
--- a/lib/utils/isString.js
+++ b/lib/utils/isString.js
@@ -1,5 +1,9 @@
 const isString = function(string) {
-  return (string && typeof string === 'string' && string !== '');
+  if (string && typeof string === 'string' && string !== '') {
+    return true;
+  } else {
+    return false;
+  }
 };
 
 module.exports = isString;
diff --git a/lib/utils/renderer.js b/lib/utils/renderer.js
index cb620d8..c7ac81a 100644
--- a/lib/utils/renderer.js
+++ b/lib/utils/renderer.js
@@ -1,22 +1,14 @@
 const emmet = require('../vendor/emmet');
 const isString = require('./isString');
+const sanitizeForEmmet = require('./cssSelector').sanitizeForEmmet;
+const hasProp = require('./object').hasProp;
 
-const sanitize = (selectors = '') => {
-  return selectors.trim()
-    .replace(/\ > \ /g, ' ')
-    .replace(/>/g, ' ')
-    .replace(/\ \ \ \ /g, ' ')
-    .replace(/\ \ \ /g, ' ')
-    .replace(/\ \ /g, ' ')
-    .replace(/\ /g, ' > ');
-};
-
-const renderer = (document, selectors) => {
-  if (!document || !isString(selectors)) {
-    return;
+const renderer = (document = false, selectors = '') => {
+  if (!document || !hasProp(document, 'location') || !isString(selectors)) {
+    return false;
   }
 
-  return emmet(document, sanitize(selectors));
+  return emmet(document, sanitizeForEmmet(selectors));
 };
 
 module.exports = renderer;
diff --git a/lib/utils/sass.js b/lib/utils/sass.js
index 675ec8d..1dcd8cf 100644
--- a/lib/utils/sass.js
+++ b/lib/utils/sass.js
@@ -34,7 +34,7 @@ const getOptions = (o = defaultOptions) => {
   return opts;
 };
 
-const render = (o = {}) => {
+const render = (o = defaultOptions) => {
   const opts = getOptions(o);
 
   return opts ? nodeSass.renderSync(opts).css.toString() : false;
diff --git a/test/setup.mocha.js b/test/setup.mocha.js
index 92e2885..c25a26d 100644
--- a/test/setup.mocha.js
+++ b/test/setup.mocha.js
@@ -26,6 +26,9 @@ global.utils = {
   cssFile: require('../lib/utils/cssFile'),
   cssSelector: require('../lib/utils/cssSelector'),
   cssom: require('../lib/utils/cssom'),
+  isString: require('../lib/utils/isString'),
   isValid: require('../lib/utils/isValid'),
+  renderer: require('../lib/utils/renderer'),
   resolve: require('../lib/utils/resolve'),
+  sass: require('../lib/utils/sass'),
 };
diff --git a/test/unit/utils/cssSelector.js b/test/unit/utils/cssSelector.js
index d5b1694..a534021 100644
--- a/test/unit/utils/cssSelector.js
+++ b/test/unit/utils/cssSelector.js
@@ -22,6 +22,27 @@ describe('utils', () => {
       });
     });
 
+    describe('.sanitizeForEmmet()', () => {
+      const fn = cssSelector.sanitizeForEmmet;
+
+      it('should return false if arguments are invalid', () => {
+        expect(fn()).to.be.false;
+        expect(fn('')).to.be.false;
+      });
+
+      it('should trim whitespace before/after string', () => {
+        expect(fn(' div ')).to.equal('div');
+      });
+
+      it('should add > symbol for space', () => {
+        expect(fn('div li')).to.equal('div > li');
+      });
+
+      it('should resolve excess spacing', () => {
+        expect(fn('div     li')).to.equal('div > li');
+      });
+    });
+
     describe('.split()', () => {
       const fn = cssSelector.split;
 
diff --git a/test/unit/utils/cssom.js b/test/unit/utils/cssom.js
index ff4468e..6b1cf65 100644
--- a/test/unit/utils/cssom.js
+++ b/test/unit/utils/cssom.js
@@ -14,6 +14,117 @@ describe('utils', () => {
       });
     });
 
+    describe('.isRule()', () => {
+      const fn = cssom.isRule;
+
+      it('should return true if valid (based on PostCSS AST)', () => {
+        expect(fn()).to.be.false;
+        expect(fn({})).to.be.false;
+        expect(fn({ type: 'rule' })).to.be.true;
+      });
+    });
+
+    describe('.isSelector()', () => {
+      const fn = cssom.isSelector;
+
+      it('should return true if valid (based on PostCSS AST)', () => {
+        expect(fn()).to.be.false;
+        expect(fn({})).to.be.false;
+        expect(fn({ nodes: true })).to.be.true;
+      });
+    });
+
+    describe('.findSelectorsFromNodes()', () => {
+      const fn = cssom.findSelectorsFromNodes;
+
+      it('should return false if invalid args', () => {
+        expect(fn()).to.be.false;
+        expect(fn(true, '')).to.be.false;
+        expect(fn({}, '.body')).to.be.false;
+      });
+
+      it('should return empty array if selectors cannot be found from nodes', () => {
+        expect(fn([{ selector: '.html' }], '.body')).to.be.an('array').and.to.have.lengthOf(0);
+      });
+
+      it('should return selector it exists in node', () => {
+        expect(fn([{ selector: '.body' }], '.body')).to.be.an('array').and.to.have.lengthOf(1);
+      });
+    });
+
+    describe('.findSelectorFromParamsByString()', () => {
+      const fn = cssom.findSelectorFromParamsByString;
+
+      it('should return false if invalid args', () => {
+        expect(fn()).to.be.false;
+        expect(fn(true, '')).to.be.false;
+        expect(fn({}, '.body')).to.be.false;
+      });
+    });
+
+    describe('.findSelectorFromParamsByArray()', () => {
+      const fn = cssom.findSelectorFromParamsByArray;
+
+      it('should return false if invalid args', () => {
+        expect(fn()).to.be.undefined;
+        expect(fn(true, '')).to.be.false;
+        expect(fn({}, '.body')).to.be.false;
+        expect(fn([], '.body')).to.be.false;
+        expect(fn([], [])).to.be.undefined;
+      });
+    });
+
+    describe('.getAtRules()', () => {
+      const fn = cssom.getAtRules;
+
+      it('should return empty array if invalid args', () => {
+        expect(fn()).to.be.an('array').and.have.lengthOf(0);
+        expect(fn([], '')).to.be.an('array').and.have.lengthOf(0);
+      });
+    });
+
+    describe('.getAtRuleFromSelector()', () => {
+      const fn = cssom.getAtRuleFromSelector;
+
+      it('should return false if selector isn\'t a nested rule', () => {
+        expect(fn()).to.be.false;
+        expect(fn('.selector')).to.be.false;
+        expect(fn({ selector: '.selector'})).to.be.false;
+      });
+
+      it('should return rule if selector is a nested rule', () => {
+        expect(fn({ parent: { type: 'atrule' } })).to.not.be.false;
+      });
+    });
+
+    describe('.getParamNodes', () => {
+      const fn = cssom.getParamNodes;
+
+      it('should return empty array if invalid args', () => {
+        expect(fn()).to.be.an('array').and.to.have.lengthOf(0);
+        expect(fn('true')).to.be.an('array').and.to.have.lengthOf(0);
+        expect(fn(true)).to.be.an('array').and.to.have.lengthOf(0);
+      });
+    });
+
+    describe('.getPropsFromSelector()', () => {
+      const fn = cssom.getPropsFromSelector;
+
+      it('should return false if invalid args', () => {
+        expect(fn()).to.be.false;
+        expect(fn({})).to.be.false;
+      });
+    });
+
+    describe('.getPropDataFromSelector()', () => {
+      const fn = cssom.getPropDataFromSelector;
+
+      it('should return false if invalid args', () => {
+        expect(fn()).to.be.false;
+        expect(fn({}, '')).to.be.false;
+      });
+    });
+
     describe('.getRuleParams()', () => {
       const fn = cssom.getRuleParams;
 
@@ -54,5 +165,24 @@ describe('utils', () => {
         expect(cssom.type).to.equal('root');
       });
     });
+
+    describe('.sanitizeParens()', () => {
+      const fn = cssom.sanitizeParens;
+
+      it('should return arg if arg (string) is invalid', () => {
+        expect(fn('')).to.equal('');
+        expect(fn(true)).to.equal(true);
+        expect(fn(123)).to.equal(123);
+      });
+
+      it('should strip parenthesis', () => {
+        expect(fn('((content))(rule)((()))')).to.not.contain('(');
+        expect(fn('((content))(rule)((()))')).to.not.contain(')');
+      });
+
+      it('should return rule in lowercase', () => {
+        expect(fn('(CoNtEnT)')).to.equal('content');
+      });
+    });
   });
 });
diff --git a/test/unit/utils/isString.js b/test/unit/utils/isString.js
new file mode 100644
index 0000000..f56e473
--- /dev/null
+++ b/test/unit/utils/isString.js
@@ -0,0 +1,27 @@
+/* globals barista: true, expect: true, describe: true, it: true, sinon: true, utils: true */
+
+const isString = global.utils.isString;
+
+describe('utils', () => {
+  describe('isString', () => {
+    it('should return false for non-strings', () => {
+      expect(isString(0)).to.be.false;
+      expect(isString(1)).to.be.false;
+      expect(isString([])).to.be.false;
+      expect(isString(true)).to.be.false;
+      expect(isString(false)).to.be.false;
+      expect(isString({})).to.be.false;
+      expect(isString()).to.be.false;
+    });
+
+    it('should return false for empty strings', () => {
+      expect(isString('')).to.be.false;
+    });
+
+    it('should return true for non-empty strings', () => {
+      expect(isString('y')).to.be.true;
+      expect(isString('yiss')).to.be.true;
+      expect(isString('aw yiss')).to.be.true;
+    });
+  });
+});
diff --git a/test/unit/utils/renderer.js b/test/unit/utils/renderer.js
new file mode 100644
index 0000000..81de853
--- /dev/null
+++ b/test/unit/utils/renderer.js
@@ -0,0 +1,13 @@
+/* globals barista: true, expect: true, describe: true, it: true, sinon: true, utils: true */
+
+const renderer = global.utils.renderer;
+
+describe('utils', () => {
+  describe('renderer', () => {
+    it('should return false for invalid args', () => {
+      expect(renderer(true, '')).to.be.false;
+      expect(renderer(true, '.selector')).to.be.false;
+      expect(renderer({}, '.selector')).to.be.false;
+    });
+  });
+});
diff --git a/test/unit/utils/sass.js b/test/unit/utils/sass.js
new file mode 100644
index 0000000..ba90713
--- /dev/null
+++ b/test/unit/utils/sass.js
@@ -0,0 +1,23 @@
+/* globals barista: true, expect: true, describe: true, it: true, sinon: true, utils: true */
+
+const sass = global.utils.sass;
+
+describe('utils', () => {
+  describe('sass', () => {
+    describe('render', () => {
+      it('should render CSS with valid option.content', () => {
+        const output = sass.render({ content: 'h1 { color: black; }' });
+
+        expect(output).to.be.a('string');
+        expect(output).to.contain('h1');
+      });
+
+      it('should render SCSS with valid option.content', () => {
+        const output = sass.render({ content: 'h1 { color: black; a { display: block; } }' });
+
+        expect(output).to.be.a('string');
+        expect(output).to.contain('h1 a');
+      });
+    });
+  });
+});