diff --git a/constants.js b/constants.js
index 5392926..1713dc5 100644
--- a/constants.js
+++ b/constants.js
@@ -1,6 +1,6 @@
 module.exports = {
-  SOURCE: 'templates',
-  DIST: 'dist',
+  SOURCE_DIR: 'templates',
+  DIST_DIR: 'dist',
   WORKING_DIR: 'tmp',
   CONFIGURATION_FILE: 'conf.json'
 }
diff --git a/gulpfile.js b/gulpfile.js
index b4421e2..f28957a 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1,11 +1,11 @@
 const gulp = require('gulp');
 const plumber = require('gulp-plumber');
 
-const { SOURCE, DIST, WORKING_DIR, CONFIGURATION_FILE } = require('./constants');
+const { SOURCE_DIR, DIST_DIR, WORKING_DIR, CONFIGURATION_FILE } = require('./constants');
 
 const options = {
-  source: SOURCE,
-  dist: DIST,
+  sourceDir: SOURCE_DIR,
+  distDir: DIST_DIR,
   workingDir: WORKING_DIR,
   configurationFile: CONFIGURATION_FILE,
   src: function plumbedSrc() {
@@ -22,11 +22,14 @@ require('./tasks/less')(options);
 require('./tasks/lint')(options);
 require('./tasks/postcss')(options);
 require('./tasks/sass')(options);
-require('./tasks/check-for-missing')(options);
+require('./tasks/check-for-unused').checkForUnusedTask(options);
 require('./tasks/check-deps')(options);
 
 /* Runs the entire pipeline once. */
-gulp.task('run-pipeline', gulp.series('dupe', 'less', 'sass', 'postcss', 'lint', 'build', 'check-for-missing'));
+gulp.task(
+  'run-pipeline',
+  gulp.series('dupe', 'less', 'sass', 'postcss', 'lint', 'build', gulp.parallel('check-for-unused'))
+);
 
 /* By default templates will be built into '/dist'. */
 gulp.task(
@@ -35,11 +38,11 @@ gulp.task(
     /* gulp will watch for changes in '/templates'. */
     gulp.watch(
       [
-        options.source + '/**/*.html',
-        options.source + '/**/*.css',
-        options.source + '/**/*.scss',
-        options.source + '/**/*.less',
-        options.source + '/**/conf.json'
+        options.sourceDir + '/**/*.html',
+        options.sourceDir + '/**/*.css',
+        options.sourceDir + '/**/*.scss',
+        options.sourceDir + '/**/*.less',
+        options.sourceDir + '/**/conf.json'
       ],
       { delay: 500 },
       gulp.series('run-pipeline')
diff --git a/package-lock.json b/package-lock.json
index 1d2de05..eb64d89 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1635,9 +1635,9 @@
       }
     },
     "chalk": {
-      "version": "2.4.1",
-      "resolved": "https://registry.npmjs.org/chalk/-/chalk-2.4.1.tgz",
-      "integrity": "sha512-ObN6h1v2fTJSmUXoS3nMQ92LbDK9be4TV+6G+omQlGJFdcUX5heKi1LZ1YnRMIgwTLEj3E24bT6tYni50rlCfQ==",
+      "version": "2.4.2",
+      "resolved": "https://registry.npmjs.org/chalk/-/chalk-2.4.2.tgz",
+      "integrity": "sha512-Mti+f9lpJNcwF4tWV8/OrTTtF1gZi+f8FqlyAdouralcFWFQWF2+NgCHShjkCb+IFBLq9buZwE1xckQU4peSuQ==",
       "requires": {
         "ansi-styles": "^3.2.1",
         "escape-string-regexp": "^1.0.5",
diff --git a/package.json b/package.json
index 9bbb218..7521521 100644
--- a/package.json
+++ b/package.json
@@ -26,13 +26,13 @@
     "start": "node ./node_modules/.bin/gulp",
     "once": "node ./node_modules/.bin/gulp run-pipeline",
     "deploy": "npm run test && cp -r dist demo && git push origin `git subtree split --prefix demo develop`:gh-pages --force",
-    "test": "npm run once && node ./node_modules/.bin/ava",
-    "test:watch": "npm run once && node ./node_modules/.bin/ava --watch",
-    "format": "node ./node_modules/.bin/prettier {tasks,tests}/**/*.js gulpfile.js .eslintrc.js --write",
-    "lint": "node ./node_modules/.bin/eslint ./**/*.js gulpfile.js"
+    "e2e-test": "npm run once && node ./node_modules/.bin/ava",
+    "format": "prettier {tasks,tests}/**/*.js gulpfile.js .eslintrc.js --write",
+    "lint": "eslint ./**/*.js gulpfile.js"
   },
   "dependencies": {
-    "autoprefixer": "^9.7.4",
+    "autoprefixer": "^9.6.1",
+    "chalk": "^2.4.2",
     "del": "^5.1.0",
     "graceful-fs": "^4.2.3",
     "gulp": "^4.0.2",
diff --git a/tasks/build.js b/tasks/build.js
index ea92b30..b0a072d 100644
--- a/tasks/build.js
+++ b/tasks/build.js
@@ -58,7 +58,7 @@ function buildTask(options) {
               return path;
             })
           )
-          .pipe(gulp.dest(options.dist));
+          .pipe(gulp.dest(options.distDir));
       });
     }
 
@@ -66,7 +66,7 @@ function buildTask(options) {
      * Clean up & then read from workingDir to generate templates.
      * For each found config, a template group will be generated through `makeTemplates`.
      */
-    return del(options.dist)
+    return del(options.distDir)
       .then(() => {
         /**
          * Loop through dirs and load their conf files.
diff --git a/tasks/check-for-missing.js b/tasks/check-for-missing.js
index c4d6af3..890cdcf 100644
--- a/tasks/check-for-missing.js
+++ b/tasks/check-for-missing.js
@@ -1,28 +1,9 @@
 const gulp = require('gulp');
-const { getConfigsForDir, getFilePathsForDir } = require('./util/util');
 
-function checkForMissingTask(options) {
-  gulp.task('check-for-missing', done => {
-    const configs = getConfigsForDir(options.workingDir, options.configurationFile);
-
-    configs.map(({ dir, confItems }) => {
-      confItems.forEach(async confItem => {
-        const definedStrings = Object.keys(confItem).map(key => {
-          return {
-            src: `@echo ${key}`,
-            used: false
-          };
-        });
-
-        const cwd = `${options.workingDir}/${dir}`;
-        const files = await getFilePathsForDir(cwd);
-        const htmlTemplates = files.filter(file => !!file.match(/.*\.html/) && !file.match(/.*\.inc*\.html/)); // Read only CSS files.
-        console.log(definedStrings, htmlTemplates);
-      });
-
-      done();
-    });
+function checkForUnusedTask(options) {
+  gulp.task('check-for-unused', async done => {
+    done();
   });
 }
 
-module.exports = checkForMissingTask;
+module.exports = checkForUnusedTask;
diff --git a/tasks/check-for-unused.js b/tasks/check-for-unused.js
index e69de29..0308434 100644
--- a/tasks/check-for-unused.js
+++ b/tasks/check-for-unused.js
@@ -0,0 +1,81 @@
+const gulp = require('gulp');
+const fs = require('fs');
+const chalk = require('chalk');
+const { getConfigsForDir, getFilePathsForDir, log } = require('./util/util');
+
+const OUTPUT_KEYWORD = '@echo';
+
+// todo: needs a proper refactor.
+function checkForUnusedTask(options) {
+  gulp.task('check-for-unused', async done => {
+    const configs = getConfigsForDir(options.workingDir, options.configurationFile);
+    const unusedItems = await checkForUnusedItemsInConfigs(options.workingDir, configs);
+    outputWarningsForUnusedItems(unusedItems, configs);
+
+    done();
+  });
+}
+
+// todo: find configs by id instead of using the index?
+const outputWarningsForUnusedItems = (unusedItems, configs) => {
+  const find = OUTPUT_KEYWORD;
+  const regex = new RegExp(find, 'g');
+  unusedItems.forEach((unusedInConfigs, index) => {
+    const { dir } = configs[index];
+
+    unusedInConfigs.forEach((unusedInConfItems, index) => {
+      log.warn(
+        `${unusedInConfItems.length} unused properties in ${dir}: ${unusedInConfItems
+          .reduce((acc, cur) => (acc ? `${acc}, ${chalk.white(cur)}` : chalk.white(cur)), '')
+          .replace(regex, '')}`
+      );
+    });
+  });
+};
+
+const checkForUnusedItemsInConfigs = (rootDir, configs) => {
+  return Promise.all(
+    configs.map(async ({ dir, confItems }) => {
+      return Promise.all(
+        confItems.map(async confItem => {
+          const definedStrings = Object.keys(confItem).map(key => `${OUTPUT_KEYWORD} ${key}`);
+          const cwd = `${rootDir}/${dir}`;
+          const files = await getFilePathsForDir(cwd);
+          const htmlTemplates = await self.getHtmlTemplatesFromFilelist(files);
+          const concatenatedTemplates = htmlTemplates.join('');
+
+          return definedStrings.filter(str => concatenatedTemplates.includes(str));
+        })
+      );
+    })
+  );
+};
+
+// todo: should be util, so should the one in build.js
+const getHtmlTemplatesFromFilelist = filelist => {
+  return Promise.all(
+    filelist
+      .filter(file => !!file.match(/.*\.html/) && !file.match(/.*\.inc*\.html/))
+      .map(
+        htmlTemplate =>
+          new Promise((resolve, reject) => {
+            fs.readFile(htmlTemplate, 'utf8', (error, data) => {
+              if (error) {
+                reject(error);
+              }
+
+              resolve(data);
+            });
+          })
+      )
+  );
+};
+
+const self = {
+  checkForUnusedTask,
+  outputWarningsForUnusedItems,
+  checkForUnusedItemsInConfigs,
+  getHtmlTemplatesFromFilelist
+};
+
+module.exports = self;
diff --git a/tasks/dupe.js b/tasks/dupe.js
index 46d9fe1..412709e 100644
--- a/tasks/dupe.js
+++ b/tasks/dupe.js
@@ -5,7 +5,7 @@ function dupeTask(options) {
   gulp.task('dupe', function() {
     del.sync([options.workingDir]);
 
-    return options.src([options.source + '/**/*']).pipe(gulp.dest('./' + options.workingDir));
+    return options.src([options.sourceDir + '/**/*']).pipe(gulp.dest('./' + options.workingDir));
   });
 }
 
diff --git a/tasks/util/util.js b/tasks/util/util.js
index 57a3294..3f9a995 100644
--- a/tasks/util/util.js
+++ b/tasks/util/util.js
@@ -1,7 +1,9 @@
 const fs = require('fs');
 const path = require('path');
 const klaw = require('klaw');
+const chalk = require('chalk');
 
+// todo test
 /**
  * Given a directory, scans all directories in it (not deep) and returns found config items.
  *
@@ -16,7 +18,7 @@ const getConfigsForDir = (rootDir, configFileName) => {
 
       /** Exit with warn if no configuration file found. */
       if (!fs.existsSync(path.resolve(rootDir, confPath))) {
-        console.warn(`Missing configuration in "${dir}". Did you remember to create "${dir}/${configFileName}"?`);
+        self.log.warn(`Missing configuration in "${dir}". Did you remember to create "${dir}/${configFileName}"?`);
         return false;
       }
 
@@ -41,8 +43,11 @@ const getConfigsForDir = (rootDir, configFileName) => {
     .filter(config => config);
 };
 
+// todo test
 /**
  * Given a directory, gets all file paths in it.
+ *
+ * @param { string } dir Dir to get files paths for.
  */
 const getFilePathsForDir = dir => {
   const files = [];
@@ -63,7 +68,24 @@ const getFilePathsForDir = dir => {
   });
 };
 
-module.exports = {
+const log = {
+  warn: (...messages) => {
+    console.warn('🔵 ', chalk.yellow(messages));
+  },
+
+  log: (...messages) => {
+    console.log('🔘 ', chalk.gray(messages));
+  },
+
+  error: (...messages) => {
+    console.error('🔴 ', chalk.red(messages));
+  }
+};
+
+const self = {
+  log,
   getConfigsForDir,
   getFilePathsForDir
 };
+
+module.exports = self;
diff --git a/tests/e2e/end-to-end.test.js b/tests/e2e/end-to-end.test.js
new file mode 100644
index 0000000..5d5dcf2
--- /dev/null
+++ b/tests/e2e/end-to-end.test.js
@@ -0,0 +1,40 @@
+const test = require('ava');
+const fs = require('fs');
+const path = require('path');
+
+const readFileSync = path => fs.readFileSync(('../', path), 'utf8');
+
+test('dark signature output', async t => {
+  const expected = readFileSync('tests/sample/dark/signature-dark.html');
+  const built = readFileSync('dist/dark/signature-dark.html');
+
+  t.deepEqual(expected, built);
+});
+
+test('dark signature reply output', async t => {
+  const expected = readFileSync('tests/sample/dark/signature-reply-dark.html');
+  const built = readFileSync('dist/dark/signature-reply-dark.html');
+
+  t.deepEqual(expected, built);
+});
+
+test('light signature output', async t => {
+  const expected = readFileSync('tests/sample/light/signature-light.html');
+  const built = readFileSync('dist/light/signature-light.html');
+
+  t.deepEqual(expected, built);
+});
+
+test('light signature reply output', async t => {
+  const expected = readFileSync('tests/sample/light/signature-reply-light.html');
+  const built = readFileSync('dist/light/signature-reply-light.html');
+
+  t.deepEqual(expected, built);
+});
+
+test('light full mail output', async t => {
+  const expected = readFileSync('tests/sample/light/full-mail-light.html');
+  const built = readFileSync('dist/light/full-mail-light.html');
+
+  t.deepEqual(expected, built);
+});
diff --git a/tests/end-to-end.test.js b/tests/end-to-end.test.js
deleted file mode 100644
index ccfed2a..0000000
--- a/tests/end-to-end.test.js
+++ /dev/null
@@ -1,38 +0,0 @@
-const test = require('ava');
-const fs = require('fs');
-const path = require('path');
-
-test('dark signature output', async t => {
-  const expected = fs.readFileSync(path.resolve('tests/sample/dark/signature-dark.html'), 'utf8');
-  const built = fs.readFileSync(path.resolve('dist/dark/signature-dark.html'), 'utf8');
-
-  t.deepEqual(expected, built);
-});
-
-test('dark signature reply output', async t => {
-  const expected = fs.readFileSync(path.resolve('tests/sample/dark/signature-reply-dark.html'), 'utf8');
-  const built = fs.readFileSync(path.resolve('dist/dark/signature-reply-dark.html'), 'utf8');
-
-  t.deepEqual(expected, built);
-});
-
-test('light signature output', async t => {
-  const expected = fs.readFileSync(path.resolve('tests/sample/light/signature-light.html'), 'utf8');
-  const built = fs.readFileSync(path.resolve('dist/light/signature-light.html'), 'utf8');
-
-  t.deepEqual(expected, built);
-});
-
-test('light signature reply output', async t => {
-  const expected = fs.readFileSync(path.resolve('tests/sample/light/signature-reply-light.html'), 'utf8');
-  const built = fs.readFileSync(path.resolve('dist/light/signature-reply-light.html'), 'utf8');
-
-  t.deepEqual(expected, built);
-});
-
-test('light full mail output', async t => {
-  const expected = fs.readFileSync(path.resolve('tests/sample/light/full-mail-light.html'), 'utf8');
-  const built = fs.readFileSync(path.resolve('dist/light/full-mail-light.html'), 'utf8');
-
-  t.deepEqual(expected, built);
-});
diff --git a/tests/unit/check-for-unused.js b/tests/unit/check-for-unused.js
new file mode 100644
index 0000000..e69de29
diff --git a/tests/unit/util.js b/tests/unit/util.js
new file mode 100644
index 0000000..e69de29