diff --git a/.codeclimate.yml b/.codeclimate.yml
index 1b449f2..42e43fe 100644
--- a/.codeclimate.yml
+++ b/.codeclimate.yml
@@ -1,8 +1,7 @@
 engines:
-  rubocop:
+  eslint:
     enabled: true
-ratings:
-  paths:
-  - "**.rb"
+    channel: eslint-4
 exclude_paths:
-  - spec/**/*
+  - test/**/*
+  - node_modules/**/*
diff --git a/.dockerignore b/.dockerignore
index cf6ce25..01d2a07 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,2 +1,3 @@
 .git
 Makefile
+node_modules
diff --git a/.eslintrc b/.eslintrc
new file mode 100644
index 0000000..63664eb
--- /dev/null
+++ b/.eslintrc
@@ -0,0 +1,32 @@
+{
+  "env": {
+    "node": true,
+    "mocha": true,
+    "es6": true
+  },
+  "rules": {
+    "block-spacing": 2,
+    "brace-style": [2, "1tbs", { "allowSingleLine": true }],
+    "comma-dangle": [2, "never"],
+    "comma-style": [2, "first", { exceptions: {ArrayExpression: true, ObjectExpression: true} }],
+    "complexity": [2, 6],
+    "curly": 2,
+    "eqeqeq": [2, "allow-null"],
+    "max-statements": [2, 30],
+    "no-shadow-restricted-names": 2,
+    "no-undef": 2,
+    "no-use-before-define": 2,
+    "radix": 2,
+    "semi": 2,
+    "space-infix-ops": 2,
+    "strict": 0
+  },
+  "globals": {
+    "AnalysisView": true,
+    "PollingView": true,
+    "Prism": true,
+    "Spinner": true,
+    "Timer": true,
+    "moment": true
+  }
+}
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c2658d7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+node_modules/
diff --git a/.rubocop.yml b/.rubocop.yml
deleted file mode 100644
index 6583489..0000000
--- a/.rubocop.yml
+++ /dev/null
@@ -1,41 +0,0 @@
-Style/StringLiterals:
-  Enabled: false
-
-Style/Documentation:
-  Enabled: false
-
-Metrics/LineLength:
-  Enabled: false
-
-Style/TrailingComma:
-  Enabled: false
-
-Style/FileName:
-  Exclude:
-    - 'bin/**/*'
-
-Style/ClassAndModuleChildren:
-  Exclude:
-    - 'spec/**/*'
-
-Metrics/ModuleLength:
-  Exclude:
-    - 'spec/**/*'
-
-Style/GuardClause:
-  Enabled: false
-
-Style/IfUnlessModifier:
-  Enabled: false
-
-Style/DotPosition:
-  Enabled: false
-
-Style/SignalException:
-  Enabled: false
-
-Metrics/AbcSize:
-  Enabled: false
-
-Rails/TimeZone:
-  Enabled: false
diff --git a/.ruby-version b/.ruby-version
deleted file mode 100644
index 5859406..0000000
--- a/.ruby-version
+++ /dev/null
@@ -1 +0,0 @@
-2.2.3
diff --git a/Dockerfile b/Dockerfile
index 950153c..4f271fa 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,19 +1,26 @@
-FROM codeclimate/alpine-ruby:b38
+FROM node:alpine
+LABEL maintainer="Code Climate <hello@codeclimate.com>"
+
+RUN adduser -u 9000 -D app
 
 WORKDIR /usr/src/app
-COPY Gemfile /usr/src/app/
-COPY Gemfile.lock /usr/src/app/
 
-RUN apk --update add nodejs git zlib zlib-dev ruby ruby-dev ruby-bundler less build-base && \
-    bundle install -j 4 && \
-    apk del --purge build-base zlib zlib-dev && rm -fr /usr/share/ri
+COPY package.json yarn.lock engine.json ./
 
-ENV CSSLINT_SHA=87aa604a4cbc5125db979576f1b09b35980fcf08
-RUN npm install -g codeclimate/csslint.git#$CSSLINT_SHA
+RUN yarn install && \
+  chown -R app:app ./ && \
+  apk add --no-cache --virtual .dev-deps jq && \
+  export csslint_version=$(yarn --json list --pattern csslint 2>/dev/null | jq -r '.data.trees[0].name' | cut -d@ -f2) && \
+  cat engine.json | jq '.version = .version + "/" + env.csslint_version' > /engine.json && \
+  apk del .dev-deps
 
-RUN adduser -u 9000 -D app
-USER app
+COPY . ./
 
 COPY . /usr/src/app
 
+USER app
+
+VOLUME /code
+WORKDIR /code
+
 CMD ["/usr/src/app/bin/csslint"]
diff --git a/Gemfile b/Gemfile
deleted file mode 100644
index 76ec3ca..0000000
--- a/Gemfile
+++ /dev/null
@@ -1,10 +0,0 @@
-source "https://rubygems.org"
-
-gem 'json'
-gem 'nokogiri'
-gem "pry"
-
-group :test do
-  gem "rake"
-  gem "rspec"
-end
diff --git a/Gemfile.lock b/Gemfile.lock
deleted file mode 100644
index 99ebd75..0000000
--- a/Gemfile.lock
+++ /dev/null
@@ -1,44 +0,0 @@
-GEM
-  remote: https://rubygems.org/
-  specs:
-    coderay (1.1.0)
-    diff-lcs (1.2.5)
-    json (1.8.3)
-    method_source (0.8.2)
-    mini_portile2 (2.1.0)
-    nokogiri (1.6.8)
-      mini_portile2 (~> 2.1.0)
-      pkg-config (~> 1.1.7)
-    pkg-config (1.1.7)
-    pry (0.10.1)
-      coderay (~> 1.1.0)
-      method_source (~> 0.8.1)
-      slop (~> 3.4)
-    rake (10.4.2)
-    rspec (3.2.0)
-      rspec-core (~> 3.2.0)
-      rspec-expectations (~> 3.2.0)
-      rspec-mocks (~> 3.2.0)
-    rspec-core (3.2.3)
-      rspec-support (~> 3.2.0)
-    rspec-expectations (3.2.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-mocks (3.2.1)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-support (3.2.2)
-    slop (3.6.0)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  json
-  nokogiri
-  pry
-  rake
-  rspec
-
-BUNDLED WITH
-   1.10.6
diff --git a/Makefile b/Makefile
index cb4fb3e..43b56ef 100644
--- a/Makefile
+++ b/Makefile
@@ -4,4 +4,4 @@ image:
 	docker build -t codeclimate/codeclimate-csslint .
 
 test: image
-	docker run --rm codeclimate/codeclimate-csslint rspec $(RSPEC_ARGS)
+	docker run --rm codeclimate/codeclimate-csslint sh -c "cd /usr/src/app && npm run test"
diff --git a/Rakefile b/Rakefile
deleted file mode 100644
index 8281788..0000000
--- a/Rakefile
+++ /dev/null
@@ -1,5 +0,0 @@
-require "rspec/core/rake_task"
-
-RSpec::Core::RakeTask.new(:spec)
-
-task default: :spec
diff --git a/bin/csslint b/bin/csslint
index 8b2417d..d9c7377 100755
--- a/bin/csslint
+++ b/bin/csslint
@@ -1,14 +1,10 @@
-#!/usr/bin/env ruby
-$LOAD_PATH.unshift(File.expand_path(File.join(File.dirname(__FILE__), "../lib")))
+#!/usr/local/bin/node --expose-gc
 
-require 'cc/engine/csslint'
+const fs = require("fs");
+const Engine = require("../lib/csslint");
 
-if File.exists?("/config.json")
-  engine_config = JSON.parse(File.read("/config.json"))
-else
-  engine_config = {}
-end
+const CONFIG_PATH = "/config.json";
+let config = JSON.parse(fs.readFileSync(CONFIG_PATH));
 
-CC::Engine::CSSlint.new(
-  directory: "/code", engine_config: engine_config, io: STDOUT
-).run
+const CODE_DIR = "/code";
+new Engine(CODE_DIR, console, config).run();
diff --git a/bin/csslint.rb b/bin/csslint.rb
new file mode 100755
index 0000000..8b2417d
--- /dev/null
+++ b/bin/csslint.rb
@@ -0,0 +1,14 @@
+#!/usr/bin/env ruby
+$LOAD_PATH.unshift(File.expand_path(File.join(File.dirname(__FILE__), "../lib")))
+
+require 'cc/engine/csslint'
+
+if File.exists?("/config.json")
+  engine_config = JSON.parse(File.read("/config.json"))
+else
+  engine_config = {}
+end
+
+CC::Engine::CSSlint.new(
+  directory: "/code", engine_config: engine_config, io: STDOUT
+).run
diff --git a/engine.json b/engine.json
new file mode 100644
index 0000000..6909387
--- /dev/null
+++ b/engine.json
@@ -0,0 +1,13 @@
+{
+  "name": "CSSLint",
+  "description": "CSSLint is a tool to help point out problems with your CSS code.",
+  "maintainer": {
+    "name": "Code Climate",
+    "email": "hello@codeclimate.com"
+  },
+  "languages": [
+    "CSS"
+  ],
+  "version": "2.0.0",
+  "spec_version": "0.3.1"
+}
diff --git a/lib/cc/engine/csslint.rb b/lib/cc/engine/csslint.rb
deleted file mode 100644
index fbe3c4d..0000000
--- a/lib/cc/engine/csslint.rb
+++ /dev/null
@@ -1,92 +0,0 @@
-require "json"
-require "nokogiri"
-require "ostruct"
-require "shellwords"
-
-module CC
-  module Engine
-    MissingAttributesError = Class.new(StandardError)
-
-    DEFAULT_IDENTIFIER = OpenStruct.new(value: "parse-error")
-
-    class CSSlint
-      DEFAULT_EXTENSIONS = [".css"].freeze
-
-      autoload :CheckDetails, "cc/engine/csslint/check_details"
-
-      def initialize(directory: , io: , engine_config: )
-        @directory = directory
-        @engine_config = engine_config
-        @io = io
-      end
-
-      def run
-        Dir.chdir(@directory) do
-          results.xpath('//file').each do |file|
-            path = file['name'].sub(/\A#{@directory}\//, '')
-            file.children.each do |node|
-              next unless node.name == "error"
-              issue = create_issue(node, path)
-              puts("#{issue.to_json}\0")
-            end
-          end
-        end
-      end
-
-      private
-
-      attr_reader :engine_config
-
-      # rubocop:disable Metrics/MethodLength
-      def create_issue(node, path)
-        check_name = node.attributes.fetch("identifier", DEFAULT_IDENTIFIER).value
-        check_details = CheckDetails.fetch(check_name)
-
-        {
-          type: "issue",
-          check_name: check_name,
-          description: node.attributes.fetch("message").value,
-          categories: check_details.categories,
-          remediation_points: check_details.remediation_points,
-          location: {
-            path: path,
-            positions: {
-              begin: {
-                line: node.attributes.fetch("line").value.to_i,
-                column: node.attributes.fetch("column").value.to_i
-              },
-              end: {
-                line: node.attributes.fetch("line").value.to_i,
-                column: node.attributes.fetch("column").value.to_i
-              }
-            }
-          }
-        }
-      rescue KeyError => ex
-        raise MissingAttributesError, "#{ex.message} on XML '#{node}' when analyzing file '#{path}'"
-      end
-      # rubocop:enable Metrics/MethodLength
-
-      def results
-        @results ||= Nokogiri::XML(csslint_xml)
-      end
-
-      def csslint_xml
-        `csslint --format=checkstyle-xml #{files_to_inspect.shelljoin}`
-      end
-
-      def files_to_inspect
-        include_paths = engine_config.fetch("include_paths", ["./"])
-        extensions = engine_config.fetch("config", {}).fetch("extensions", DEFAULT_EXTENSIONS)
-        extensions_glob = extensions.join(",")
-        include_paths.flat_map do |path|
-          if path.end_with?("/")
-            Dir.glob("#{File.expand_path path}/**/*{#{extensions_glob}}")
-          elsif path.end_with?(*extensions)
-            path
-          end
-        end.compact
-      end
-    end
-  end
-end
diff --git a/lib/cc/engine/csslint/check_details.rb b/lib/cc/engine/csslint/check_details.rb
deleted file mode 100644
index d268634..0000000
--- a/lib/cc/engine/csslint/check_details.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-module CC
-  module Engine
-    class CSSlint
-      class CheckDetails
-        ALL_RULES = {
-          # https://github.com/CSSLint/csslint/wiki/Rules
-          "adjoining-classes" => { categories: "Compatibility" },
-          "box-model" => { categories: "Bug Risk" },
-          "box-sizing" => { categories: "Compatibility" },
-          "bulletproof-font-face" => { categories: "Compatibility" },
-          "compatible-vendor-prefixes" => { categories: "Compatibility" },
-          "display-property-grouping" => { categories: "Bug Risk" },
-          "duplicate-background-images" => { categories: "Bug Risk" },
-          "duplicate-properties" => { categories: "Bug Risk" },
-          "empty-rules" => { categories: "Bug Risk" },
-          "fallback-colors" => { categories: "Compatibility" },
-          "font-faces" => { categories: "Bug Risk" },
-          "gradients" => { categories: "Compatibility" },
-          "import" => { categories: "Bug Risk" },
-          "known-properties" => { categories: "Bug Risk" },
-          "overqualified-elements" => { categories: "Bug Risk" },
-          "parse-error" => { categories: "Bug Risk" },
-          "regex-selectors" => { categories: "Bug Risk" },
-          "shorthand" => { categories: "Bug Risk" },
-          "star-property-hack" => { categories: "Compatibility" },
-          "text-indent" => { categories: "Compatibility" },
-          "underscore-property-hack" => { categories: "Compatibility" },
-          "unique-headings" => { categories: "Duplication" },
-          "universal-selector" => { categories: "Bug Risk" },
-          "unqualified-attributes" => { categories: "Bug Risk" },
-          "vendor-prefix" => { categories: "Compatibility" },
-          "zero-units" => { categories: "Bug Risk" },
-        }.freeze
-
-        DEFAULT_CATEGORY = "Style".freeze
-        DEFAULT_REMEDIATION_POINTS = 50_000.freeze
-
-        attr_reader :categories, :remediation_points
-
-        def self.fetch(check_name)
-          new(ALL_RULES.fetch(check_name, {}))
-        end
-
-        def initialize(
-          categories: DEFAULT_CATEGORY,
-          remediation_points: DEFAULT_REMEDIATION_POINTS
-        )
-          @categories = Array(categories)
-          @remediation_points = remediation_points
-        end
-      end
-    end
-  end
-end
diff --git a/lib/check-details.js b/lib/check-details.js
new file mode 100644
index 0000000..13f9e47
--- /dev/null
+++ b/lib/check-details.js
@@ -0,0 +1,44 @@
+// https://github.com/CSSLint/csslint/wiki/Rules
+const ALL_RULES = {
+  "adjoining-classes": "Compatibility",
+  "box-model": "Bug Risk",
+  "box-sizing": "Compatibility",
+  "bulletproof-font-face": "Compatibility",
+  "compatible-vendor-prefixes": "Compatibility",
+  "display-property-grouping": "Bug Risk",
+  "duplicate-background-images": "Performance",
+  "duplicate-properties": "Bug Risk",
+  "empty-rules": "Bug Risk",
+  "fallback-colors": "Compatibility",
+  "floats": "Clarity",
+  "font-faces": "Performance",
+  "font-sizes": "Clarity",
+  "gradients": "Compatibility",
+  "ids": "Complexity",
+  "import": "Performance",
+  "important": "Complexity",
+  "known-properties": "Bug Risk",
+  "overqualified-elements": "Performance",
+  "parse-error": "Bug Risk",
+  "regex-selectors": "Performance",
+  "shorthand": "Performance",
+  "star-property-hack": "Compatibility",
+  "text-indent": "Compatibility",
+  "underscore-property-hack": "Compatibility",
+  "unique-headings": "Duplication",
+  "universal-selector": "Performance",
+  "unqualified-attributes": "Performance",
+  "vendor-prefix": "Compatibility",
+  "zero-units": "Performance"
+};
+
+const DEFAULT_CATEGORY = "Style";
+const DEFAULT_REMEDIATION_POINTS = 50000;
+
+module.exports = function(check_name) {
+  let category = ALL_RULES[check_name] || DEFAULT_CATEGORY;
+  return {
+    categories: [category],
+    remediation_points: DEFAULT_REMEDIATION_POINTS
+  };
+};
diff --git a/lib/codeclimate-formatter.js b/lib/codeclimate-formatter.js
new file mode 100644
index 0000000..ed9f03b
--- /dev/null
+++ b/lib/codeclimate-formatter.js
@@ -0,0 +1,78 @@
+"use strict";
+
+const checkDetails = require('./check-details');
+
+const DEFAULT_IDENTIFIER = "parse-error";
+const forEach = require("csslint/dist/csslint-node").CSSLint.Util.forEach;
+
+function ruleIdentifier(rule) {
+  if (!rule || !("id" in rule)) {
+    return "generic";
+  }
+  return rule.id;
+};
+
+function reportJSON(filename, report) {
+  let check_name = report.rule ? ruleIdentifier(report.rule) : DEFAULT_IDENTIFIER;
+  let details = checkDetails(check_name);
+
+  return JSON.stringify({
+    type: "issue",
+    check_name: check_name,
+    description: report.message,
+    categories: details.categories,
+    remediation_points: details.remediation_points,
+    location: {
+      path: filename,
+      positions: {
+        begin: {
+          line: report.line || 1,
+          column: report.col || 1
+        },
+        end: {
+          line: report.line || 1,
+          column: report.col || 1
+        }
+      }
+    }
+  }) + "\x00";
+}
+
+module.exports = {
+  // format information
+  id: "codeclimate",
+  name: "Code Climate format",
+
+  startFormat: function() {
+    return "";
+  },
+  endFormat: function() {
+    return "";
+  },
+
+  readError: function(filename, message) {
+    let report = {
+      type: "error",
+      line: 1,
+      col: 1,
+      message : message
+    };
+    return reportJSON(filename, report);
+  },
+
+  formatResults: function(results, filename/*, options*/) {
+    let reports = results.messages;
+    let output = [];
+
+    if (reports.length > 0) {
+      forEach(reports, function (report) {
+        // ignore rollups for now
+        if (!report.rollup) {
+          output.push(reportJSON(filename, report));
+        }
+      });
+    }
+
+    return output.join("");
+  }
+};
diff --git a/lib/csslint.js b/lib/csslint.js
new file mode 100644
index 0000000..bf1dffa
--- /dev/null
+++ b/lib/csslint.js
@@ -0,0 +1,120 @@
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+const glob = require("glob");
+const CSSLint = require("csslint/dist/csslint-node").CSSLint;
+const CodeClimateFormatter = require("./codeclimate-formatter");
+
+const DEFAULT_EXTENSIONS = [".css"];
+
+CSSLint.addFormatter(CodeClimateFormatter);
+
+function readFile(filename) {
+  try {
+    return fs.readFileSync(filename, "utf-8");
+  } catch (ex) {
+    return "";
+  }
+}
+
+
+class Analyzer {
+  constructor(directory, console, config) {
+    this.directory = directory;
+    this.console = console;
+    this.config = config;
+  }
+
+  run() {
+    let files = this.expandPaths(this.config.include_paths || ["./"]);
+
+    this.processFiles(files);
+  }
+
+
+  // private =================================================================
+
+
+  print(message) {
+    this.console.log(message);
+  }
+
+  processFile(relativeFilePath) {
+    let input = readFile(path.join(this.directory, relativeFilePath));
+    let formatter = CSSLint.getFormatter("codeclimate");
+
+    if (!input) {
+      this.print(formatter.readError(relativeFilePath, "Could not read file data. Is the file empty?"));
+    } else {
+      let result = CSSLint.verify(input);
+      let messages = result.messages || [];
+      let output = formatter.formatResults(result, relativeFilePath);
+      if (output) {
+        this.print(output);
+      }
+    }
+  }
+
+
+  processFiles(files) {
+    for (let file of files) {
+      this.processFile(file);
+    }
+  }
+
+
+  expandPaths(paths) {
+    let files = [];
+
+    for (let path of paths) {
+      let new_files = this.getFiles(path, this.directory);
+      files = files.concat(new_files);
+    }
+
+    return files;
+  }
+
+  getFiles(pathname) {
+    var files = [];
+    let full_pathname = path.normalize(path.join(this.directory, pathname));
+    let stat;
+    let base_name = path.basename(pathname);
+
+    try {
+      stat = fs.statSync(full_pathname);
+    } catch (ex) {
+      return [];
+    }
+
+    if (stat.isFile() && this.extensionsRegExp.test(full_pathname)) {
+      return [pathname];
+    } else if (stat.isDirectory()) {
+        for (let file of fs.readdirSync(full_pathname)) {
+          let new_path = path.join(full_pathname, file);
+          files = files.concat(this.getFiles(path.relative(this.directory, new_path)));
+        };
+    }
+
+    return files;
+  }
+
+  get extensionsRegExp() {
+    return RegExp(
+      (this.config.extensions || DEFAULT_EXTENSIONS).
+        map(e => e.replace('.', '\\.')).
+        join("|") +
+        "$"
+    );
+  }
+}
+
+module.exports = class {
+  constructor(directory, console, config) {
+    this.analyzer = new Analyzer(directory, console, config);
+  }
+
+  run() {
+    this.analyzer.run();
+  }
+};
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..2c01c33
--- /dev/null
+++ b/package.json
@@ -0,0 +1,25 @@
+{
+  "name": "codeclimate-csslint",
+  "version": "1.0.0",
+  "description": "Code Climate CSSLint Engine",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/codeclimate/codeclimate-csslint.git"
+  },
+  "author": "Code Climate",
+  "license": "MIT",
+  "dependencies": {
+    "csslint": "^1.0.5",
+    "glob": "^7.1.2"
+  },
+  "devDependencies": {
+    "chai": "^4.1.2",
+    "mkdirp": "^0.5.1",
+    "mocha": "^4.0.1",
+    "sinon": "^4.1.3",
+    "temp": "^0.8.3"
+  },
+  "scripts": {
+    "test": "mocha -gc test"
+  }
+}
diff --git a/spec/cc/engine/csslint/check_details_spec.rb b/spec/cc/engine/csslint/check_details_spec.rb
deleted file mode 100644
index 134dbb6..0000000
--- a/spec/cc/engine/csslint/check_details_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require "spec_helper"
-
-class CC::Engine::CSSlint
-  describe CheckDetails do
-    describe ".fetch" do
-      it "returns details for customized checks" do
-        details = CheckDetails.fetch("import")
-
-        expect(details.categories).to eq ["Bug Risk"]
-        expect(details.remediation_points).to eq 50_000
-      end
-
-      it "returns defaults for unknown checks" do
-        details = CheckDetails.fetch("made-up")
-
-        expect(details.categories).to eq ["Style"]
-        expect(details.remediation_points).to eq 50_000
-      end
-    end
-  end
-end
diff --git a/spec/cc/engine/csslint_spec.rb b/spec/cc/engine/csslint_spec.rb
deleted file mode 100644
index 6b17dfb..0000000
--- a/spec/cc/engine/csslint_spec.rb
+++ /dev/null
@@ -1,106 +0,0 @@
-require "spec_helper"
-
-module CC
-  module Engine
-    describe CSSlint do
-      let(:code) { Dir.mktmpdir }
-      let(:engine_config) { {} }
-      let(:lint) do
-        CSSlint.new(directory: code, io: nil, engine_config: engine_config)
-      end
-      let(:id_selector_content) { '#id { color: red; }' }
-
-      describe '#run' do
-        it 'analyzes *.css files' do
-          create_source_file('foo.css', id_selector_content)
-          expect{ lint.run }.to output(/Don't use IDs in selectors./).to_stdout
-        end
-
-        it 'fails on malformed file' do
-          create_source_file('foo.css', '�6�')
-          expect{ lint.run }.to output(/Unexpected token/).to_stdout
-        end
-
-        it "doesn't analyze *.scss files" do
-          create_source_file('foo.scss', id_selector_content)
-          expect{ lint.run }.to_not output.to_stdout
-        end
-
-        it "only reports issues in the file where they're present" do
-          create_source_file('bad.css', id_selector_content)
-          create_source_file('good.css', '.foo { margin: 0 }')
-          expect{ lint.run }.not_to output(/good\.css/).to_stdout
-        end
-
-        describe "with include_paths" do
-          let(:engine_config) {
-            {"include_paths" => %w(included.css included_dir/ config.yml)}
-          }
-
-          before do
-            create_source_file("included.css", id_selector_content)
-            create_source_file(
-              "included_dir/file.css", "p { color: blue !important; }"
-            )
-            create_source_file(
-              "included_dir/sub/sub/subdir/file.css", "img { }"
-            )
-            create_source_file("config.yml", "foo:\n  bar: \"baz\"")
-            create_source_file("not_included.css", "a { outline: none; }")
-          end
-
-          it "includes all mentioned files" do
-            expect{ lint.run }.to \
-              output(/Don't use IDs in selectors./).to_stdout
-          end
-
-          it "expands directories" do
-            expect{ lint.run }.to output(/Use of !important/).to_stdout
-            expect{ lint.run }.to output(/Rule is empty/).to_stdout
-          end
-
-          it "excludes any unmentioned files" do
-            expect{ lint.run }.not_to \
-              output(/Outlines should only be modified using :focus/).to_stdout
-          end
-
-          it "shouldn't call a top-level Dir.glob ever" do
-            allow(Dir).to receive(:glob).and_call_original
-            expect(Dir).not_to receive(:glob).with("**/*.css")
-            expect{ lint.run }.to \
-              output(/Don't use IDs in selectors./).to_stdout
-          end
-
-          it "only includes CSS files, even when a non-CSS file is directly included" do
-            expect{ lint.run }.not_to output(/config.yml/).to_stdout
-          end
-        end
-
-        describe "with custom extensions" do
-          let(:engine_config) do
-            {
-              "config" => {
-                "extensions" => %w(.fancycss)
-              }
-            }
-          end
-
-          before do
-            create_source_file("master.fancycss", id_selector_content)
-          end
-
-          it "takes into account extensions" do
-            expect{ lint.run }.to \
-              output(/Don't use IDs in selectors./).to_stdout
-          end
-        end
-      end
-
-      def create_source_file(path, content)
-        abs_path = File.join(code, path)
-        FileUtils.mkdir_p(File.dirname(abs_path))
-        File.write(abs_path, content)
-      end
-    end
-  end
-end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
deleted file mode 100644
index 2be99e0..0000000
--- a/spec/spec_helper.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require "cc/engine/csslint"
-require "tmpdir"
diff --git a/test/check-details-test.js b/test/check-details-test.js
new file mode 100644
index 0000000..bb8646b
--- /dev/null
+++ b/test/check-details-test.js
@@ -0,0 +1,18 @@
+const checkDetails = require("../lib/check-details");
+const expect = require("chai").expect;
+
+describe("Check Details", function() {
+  it("returns details for customized checks", function() {
+    let details = checkDetails("import");
+
+    expect(details.categories).to.deep.equal(["Performance"]);
+    expect(details.remediation_points).to.eq(50000);
+  });
+
+  it("returns defauls for unknown checks", function() {
+    let details = checkDetails("made-up");
+
+    expect(details.categories).to.deep.equal(["Style"]);
+    expect(details.remediation_points).to.eq(50000);
+  });
+});
diff --git a/test/codeclimate-formatter_test.js b/test/codeclimate-formatter_test.js
new file mode 100644
index 0000000..ad7eb10
--- /dev/null
+++ b/test/codeclimate-formatter_test.js
@@ -0,0 +1,54 @@
+const Formatter = require("../lib/codeclimate-formatter");
+const expect = require("chai").expect;
+const CSSLint = require("csslint/dist/csslint-node").CSSLint;
+
+describe("Code Climate Formatter", function() {
+  describe(".startFormat", function() {
+    it("returns a blank string", function() {
+      expect(Formatter.startFormat()).to.eq("");
+    });
+  });
+
+  describe(".endFormat", function() {
+    it("returns a blank string", function() {
+      expect(Formatter.endFormat()).to.eq("");
+    });
+  });
+
+  describe(".readError", function() {
+    it("properly serializes a read error", function() {
+      expect(Formatter.readError("foo.css", "Can not read the file")).to.eq(
+        '{"type":"issue","check_name":"parse-error","description":"Can not read the file","categories":["Bug Risk"],"remediation_points":50000,"location":{"path":"foo.css","positions":{"begin":{"line":1,"column":1},"end":{"line":1,"column":1}}}}\x00'
+      );
+    });
+  });
+
+  describe(".formatResults", function() {
+    it("properly serializes reports", function() {
+      let reports = [
+        {
+          type: "warning",
+          line: 1,
+          col: 1,
+          message: "Don't use adjoining classes.",
+          evidence: ".im-bad {",
+          rule: CSSLint.getRules().find( rule => rule.id === "adjoining-classes")
+        },
+        {
+          type: "warning",
+          line: 10,
+          col: 1,
+          message: "Disallow empty rules",
+          evidence: ".empty {}",
+          rule: CSSLint.getRules().find( rule => rule.id === "empty-rules")
+        }
+      ];
+
+      expect(Formatter.formatResults({messages: reports}, "foo.css")).to.eq(
+        '{"type":"issue","check_name":"adjoining-classes","description":"Don\'t use adjoining classes.","categories":["Compatibility"],"remediation_points":50000,"location":{"path":"foo.css","positions":{"begin":{"line":1,"column":1},"end":{"line":1,"column":1}}}}\x00' +
+        '{"type":"issue","check_name":"empty-rules","description":"Disallow empty rules","categories":["Bug Risk"],"remediation_points":50000,"location":{"path":"foo.css","positions":{"begin":{"line":10,"column":1},"end":{"line":10,"column":1}}}}\x00'
+      );
+    });
+  });
+
+});
diff --git a/test/csslint-test.js b/test/csslint-test.js
new file mode 100644
index 0000000..8892f37
--- /dev/null
+++ b/test/csslint-test.js
@@ -0,0 +1,127 @@
+const Engine = require("../lib/csslint");
+const expect = require("chai").expect;
+const CSSLint = require("csslint/dist/csslint-node").CSSLint;
+const temp = require('temp').track();
+const fs = require("fs");
+const path = require("path");
+const mkdirp = require('mkdirp').sync;
+
+class FakeConsole {
+  constructor() {
+    this.logs = [];
+    this.warns = [];
+  }
+
+  get output() {
+    return this.logs.join("\n");
+  }
+
+
+  log(str) {
+    this.logs.push(str);
+  }
+
+  warn(str) {
+    console.warn(str);
+    this.warns.push(str);
+  }
+}
+
+
+function createSourceFile(root, filename, content) {
+  let dirname = path.dirname(path.join(root, filename));
+  if (!fs.existsSync(dirname)) {
+    mkdirp(dirname);
+  }
+  fs.writeFileSync(path.join(root, filename), content);
+}
+
+describe("CSSLint Engine", function() {
+  beforeEach(function(){
+    this.id_selector_content = "#id { color: red; }";
+    this.code_dir = temp.mkdirSync("code");
+    this.console = new FakeConsole();
+    this.lint = new Engine(this.code_dir, this.console, {});
+  });
+
+  it('analyzes *.css files', function() {
+    createSourceFile(this.code_dir, 'foo.css', this.id_selector_content);
+
+    this.lint.run();
+    expect(this.console.output).to.include("Don't use IDs in selectors.");
+  });
+
+  it('fails on malformed file', function() {
+    createSourceFile(this.code_dir, 'foo.css', '�6�');
+
+    this.lint.run();
+    expect(this.console.output).to.include('Unexpected token');
+  });
+
+  it("doesn't analyze *.scss files", function() {
+    createSourceFile(this.code_dir, 'foo.scss', this.id_selector_content);
+
+    this.lint.run();
+    expect(this.console.output).to.eq('');
+  });
+
+  it("only reports issues in the file where they're present", function() {
+    createSourceFile(this.code_dir, 'bad.css', this.id_selector_content);
+    createSourceFile(this.code_dir, 'good.css', '.foo { margin: 0 }');
+
+    this.lint.run();
+    expect(this.console.output).to.not.include('good.css');
+  });
+
+  context("with include_paths", function(){
+    beforeEach(function() {
+      let engine_config = {
+        include_paths: ["included.css", "included_dir/", "config.yml"]
+      };
+      this.lint = new Engine(this.code_dir, this.console, engine_config);
+
+      createSourceFile(this.code_dir, "included.css", this.id_selector_content);
+      createSourceFile(this.code_dir, "included_dir/file.css", "p { color: blue !important; }");
+      createSourceFile(this.code_dir, "included_dir/sub/sub/subdir/file.css", "img { }");
+      createSourceFile(this.code_dir, "config.yml", "foo:\n  bar: \"baz\"");
+      createSourceFile(this.code_dir, "not_included.css", "a { outline: none; }");
+    });
+
+    it("includes all mentioned files", function() {
+      this.lint.run();
+      expect(this.console.output).to.include("Don't use IDs in selectors.");
+    });
+
+    it("expands directories", function() {
+      this.lint.run();
+      expect(this.console.output).to.include('Use of !important');
+      expect(this.console.output).to.include('Rule is empty');
+    });
+
+    it("excludes any unmentioned files", function() {
+      this.lint.run();
+      expect(this.console.output).to.not.include('Outlines should only be modified using :focus');
+    });
+
+    it("only includes CSS files, even when a non-CSS file is directly included", function() {
+      this.lint.run();
+      expect(this.console.output).to.not.include('config.yml');
+    });
+  });
+
+  context("with custom extensions", function(){
+    beforeEach(function() {
+      let engine_config = {
+        extensions: [".fancycss"]
+      };
+      this.lint = new Engine(this.code_dir, this.console, engine_config);
+
+      createSourceFile(this.code_dir, "master.fancycss", this.id_selector_content);
+    });
+
+    it("takes into account extensions", function() {
+      this.lint.run();
+      expect(this.console.output).to.include("Don't use IDs in selectors.");
+    });
+  });
+});
diff --git a/yarn.lock b/yarn.lock
new file mode 100644
index 0000000..99a6eac
--- /dev/null
+++ b/yarn.lock
@@ -0,0 +1,272 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+assertion-error@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/assertion-error/-/assertion-error-1.0.2.tgz#13ca515d86206da0bac66e834dd397d87581094c"
+
+balanced-match@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-1.0.0.tgz#89b4d199ab2bee49de164ea02b89ce462d71b767"
+
+brace-expansion@^1.1.7:
+  version "1.1.8"
+  resolved "https://registry.yarnpkg.com/brace-expansion/-/brace-expansion-1.1.8.tgz#c07b211c7c952ec1f8efd51a77ef0d1d3990a292"
+  dependencies:
+    balanced-match "^1.0.0"
+    concat-map "0.0.1"
+
+browser-stdout@1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/browser-stdout/-/browser-stdout-1.3.0.tgz#f351d32969d32fa5d7a5567154263d928ae3bd1f"
+
+chai@^4.1.2:
+  version "4.1.2"
+  resolved "https://registry.yarnpkg.com/chai/-/chai-4.1.2.tgz#0f64584ba642f0f2ace2806279f4f06ca23ad73c"
+  dependencies:
+    assertion-error "^1.0.1"
+    check-error "^1.0.1"
+    deep-eql "^3.0.0"
+    get-func-name "^2.0.0"
+    pathval "^1.0.0"
+    type-detect "^4.0.0"
+
+check-error@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/check-error/-/check-error-1.0.2.tgz#574d312edd88bb5dd8912e9286dd6c0aed4aac82"
+
+clone@~2.1.0:
+  version "2.1.1"
+  resolved "https://registry.yarnpkg.com/clone/-/clone-2.1.1.tgz#d217d1e961118e3ac9a4b8bba3285553bf647cdb"
+
+commander@2.11.0:
+  version "2.11.0"
+  resolved "https://registry.yarnpkg.com/commander/-/commander-2.11.0.tgz#157152fd1e7a6c8d98a5b715cf376df928004563"
+
+concat-map@0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/concat-map/-/concat-map-0.0.1.tgz#d8a96bd77fd68df7793a73036a3ba0d5405d477b"
+
+csslint@^1.0.5:
+  version "1.0.5"
+  resolved "https://registry.yarnpkg.com/csslint/-/csslint-1.0.5.tgz#19cc3eda322160fd3f7232af1cb2a360e898a2e9"
+  dependencies:
+    clone "~2.1.0"
+    parserlib "~1.1.1"
+
+debug@3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-3.1.0.tgz#5bb5a0672628b64149566ba16819e61518c67261"
+  dependencies:
+    ms "2.0.0"
+
+deep-eql@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-3.0.1.tgz#dfc9404400ad1c8fe023e7da1df1c147c4b444df"
+  dependencies:
+    type-detect "^4.0.0"
+
+diff@3.3.1:
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/diff/-/diff-3.3.1.tgz#aa8567a6eed03c531fc89d3f711cd0e5259dec75"
+
+diff@^3.1.0:
+  version "3.4.0"
+  resolved "https://registry.yarnpkg.com/diff/-/diff-3.4.0.tgz#b1d85507daf3964828de54b37d0d73ba67dda56c"
+
+escape-string-regexp@1.0.5:
+  version "1.0.5"
+  resolved "https://registry.yarnpkg.com/escape-string-regexp/-/escape-string-regexp-1.0.5.tgz#1b61c0562190a8dff6ae3bb2cf0200ca130b86d4"
+
+formatio@1.2.0, formatio@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/formatio/-/formatio-1.2.0.tgz#f3b2167d9068c4698a8d51f4f760a39a54d818eb"
+  dependencies:
+    samsam "1.x"
+
+fs.realpath@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
+
+get-func-name@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/get-func-name/-/get-func-name-2.0.0.tgz#ead774abee72e20409433a066366023dd6887a41"
+
+glob@7.1.2, glob@^7.1.2:
+  version "7.1.2"
+  resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.2.tgz#c19c9df9a028702d678612384a6552404c636d15"
+  dependencies:
+    fs.realpath "^1.0.0"
+    inflight "^1.0.4"
+    inherits "2"
+    minimatch "^3.0.4"
+    once "^1.3.0"
+    path-is-absolute "^1.0.0"
+
+growl@1.10.3:
+  version "1.10.3"
+  resolved "https://registry.yarnpkg.com/growl/-/growl-1.10.3.tgz#1926ba90cf3edfe2adb4927f5880bc22c66c790f"
+
+has-flag@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-2.0.0.tgz#e8207af1cc7b30d446cc70b734b5e8be18f88d51"
+
+he@1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/he/-/he-1.1.1.tgz#93410fd21b009735151f8868c2f271f3427e23fd"
+
+inflight@^1.0.4:
+  version "1.0.6"
+  resolved "https://registry.yarnpkg.com/inflight/-/inflight-1.0.6.tgz#49bd6331d7d02d0c09bc910a1075ba8165b56df9"
+  dependencies:
+    once "^1.3.0"
+    wrappy "1"
+
+inherits@2:
+  version "2.0.3"
+  resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
+
+isarray@0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/isarray/-/isarray-0.0.1.tgz#8a18acfca9a8f4177e09abfc6038939b05d1eedf"
+
+just-extend@^1.1.26:
+  version "1.1.27"
+  resolved "https://registry.yarnpkg.com/just-extend/-/just-extend-1.1.27.tgz#ec6e79410ff914e472652abfa0e603c03d60e905"
+
+lodash.get@^4.4.2:
+  version "4.4.2"
+  resolved "https://registry.yarnpkg.com/lodash.get/-/lodash.get-4.4.2.tgz#2d177f652fa31e939b4438d5341499dfa3825e99"
+
+lolex@^1.6.0:
+  version "1.6.0"
+  resolved "https://registry.yarnpkg.com/lolex/-/lolex-1.6.0.tgz#3a9a0283452a47d7439e72731b9e07d7386e49f6"
+
+lolex@^2.2.0:
+  version "2.3.1"
+  resolved "https://registry.yarnpkg.com/lolex/-/lolex-2.3.1.tgz#3d2319894471ea0950ef64692ead2a5318cff362"
+
+minimatch@^3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/minimatch/-/minimatch-3.0.4.tgz#5166e286457f03306064be5497e8dbb0c3d32083"
+  dependencies:
+    brace-expansion "^1.1.7"
+
+minimist@0.0.8:
+  version "0.0.8"
+  resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.8.tgz#857fcabfc3397d2625b8228262e86aa7a011b05d"
+
+mkdirp@0.5.1, mkdirp@^0.5.1:
+  version "0.5.1"
+  resolved "https://registry.yarnpkg.com/mkdirp/-/mkdirp-0.5.1.tgz#30057438eac6cf7f8c4767f38648d6697d75c903"
+  dependencies:
+    minimist "0.0.8"
+
+mocha@^4.0.1:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/mocha/-/mocha-4.0.1.tgz#0aee5a95cf69a4618820f5e51fa31717117daf1b"
+  dependencies:
+    browser-stdout "1.3.0"
+    commander "2.11.0"
+    debug "3.1.0"
+    diff "3.3.1"
+    escape-string-regexp "1.0.5"
+    glob "7.1.2"
+    growl "1.10.3"
+    he "1.1.1"
+    mkdirp "0.5.1"
+    supports-color "4.4.0"
+
+ms@2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/ms/-/ms-2.0.0.tgz#5608aeadfc00be6c2901df5f9861788de0d597c8"
+
+nise@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/nise/-/nise-1.2.0.tgz#079d6cadbbcb12ba30e38f1c999f36ad4d6baa53"
+  dependencies:
+    formatio "^1.2.0"
+    just-extend "^1.1.26"
+    lolex "^1.6.0"
+    path-to-regexp "^1.7.0"
+    text-encoding "^0.6.4"
+
+once@^1.3.0:
+  version "1.4.0"
+  resolved "https://registry.yarnpkg.com/once/-/once-1.4.0.tgz#583b1aa775961d4b113ac17d9c50baef9dd76bd1"
+  dependencies:
+    wrappy "1"
+
+os-tmpdir@^1.0.0:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/os-tmpdir/-/os-tmpdir-1.0.2.tgz#bbe67406c79aa85c5cfec766fe5734555dfa1274"
+
+parserlib@~1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/parserlib/-/parserlib-1.1.1.tgz#a64cfa724062434fdfc351c9a4ec2d92b94c06f4"
+
+path-is-absolute@^1.0.0:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/path-is-absolute/-/path-is-absolute-1.0.1.tgz#174b9268735534ffbc7ace6bf53a5a9e1b5c5f5f"
+
+path-to-regexp@^1.7.0:
+  version "1.7.0"
+  resolved "https://registry.yarnpkg.com/path-to-regexp/-/path-to-regexp-1.7.0.tgz#59fde0f435badacba103a84e9d3bc64e96b9937d"
+  dependencies:
+    isarray "0.0.1"
+
+pathval@^1.0.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/pathval/-/pathval-1.1.0.tgz#b942e6d4bde653005ef6b71361def8727d0645e0"
+
+rimraf@~2.2.6:
+  version "2.2.8"
+  resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.2.8.tgz#e439be2aaee327321952730f99a8929e4fc50582"
+
+samsam@1.x:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/samsam/-/samsam-1.3.0.tgz#8d1d9350e25622da30de3e44ba692b5221ab7c50"
+
+sinon@^4.1.3:
+  version "4.1.3"
+  resolved "https://registry.yarnpkg.com/sinon/-/sinon-4.1.3.tgz#fc599eda47ed9f1a694ce774b94ab44260bd7ac5"
+  dependencies:
+    diff "^3.1.0"
+    formatio "1.2.0"
+    lodash.get "^4.4.2"
+    lolex "^2.2.0"
+    nise "^1.2.0"
+    supports-color "^4.4.0"
+    type-detect "^4.0.5"
+
+supports-color@4.4.0:
+  version "4.4.0"
+  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-4.4.0.tgz#883f7ddabc165142b2a61427f3352ded195d1a3e"
+  dependencies:
+    has-flag "^2.0.0"
+
+supports-color@^4.4.0:
+  version "4.5.0"
+  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-4.5.0.tgz#be7a0de484dec5c5cddf8b3d59125044912f635b"
+  dependencies:
+    has-flag "^2.0.0"
+
+temp@^0.8.3:
+  version "0.8.3"
+  resolved "https://registry.yarnpkg.com/temp/-/temp-0.8.3.tgz#e0c6bc4d26b903124410e4fed81103014dfc1f59"
+  dependencies:
+    os-tmpdir "^1.0.0"
+    rimraf "~2.2.6"
+
+text-encoding@^0.6.4:
+  version "0.6.4"
+  resolved "https://registry.yarnpkg.com/text-encoding/-/text-encoding-0.6.4.tgz#e399a982257a276dae428bb92845cb71bdc26d19"
+
+type-detect@^4.0.0, type-detect@^4.0.5:
+  version "4.0.5"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-4.0.5.tgz#d70e5bc81db6de2a381bcaca0c6e0cbdc7635de2"
+
+wrappy@1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/wrappy/-/wrappy-1.0.2.tgz#b5243d8f3ec1aa35f1364605bc0d1036e30ab69f"