diff --git a/gulpfile.js b/gulpfile.js
index 07b82502..fbfb560b 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -32,13 +32,14 @@ const changelog = require('./scripts/changelog');
 
 const prebuild = gulp.series(clean, lint);
 const pretest = gulp.series(prebuild, build);
-const prerelease = gulp.series(pretest, test);
+const prerelease = gulp.series(pretest, test.test);
 
 module.exports = {
   'clean': clean,
   'lint': lint,
   'build': gulp.series(prebuild, build),
-  'test': gulp.series(pretest, test),
+  'test': gulp.series(pretest, test.test),
+  'tdd': gulp.series(clean, build, test.tdd),
   'changelog': changelog,
   'release:patch': gulp.series(prerelease, release.patch),
   'release:minor': gulp.series(prerelease, release.minor),
diff --git a/package.json b/package.json
index a2a23e9d..182400e2 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
     "clean": "gulp clean",
     "build": "gulp build",
     "test": "gulp test",
+    "tdd": "gulp tdd",
     "changelog": "gulp changelog",
     "release": "gulp release:minor",
     "release:patch": "gulp release:patch",
diff --git a/scripts/test/index.js b/scripts/test/index.js
index b6ee2237..931f721b 100644
--- a/scripts/test/index.js
+++ b/scripts/test/index.js
@@ -25,13 +25,39 @@
 const path = require('path');
 const gulp = require('gulp');
 const jasmine = require('gulp-jasmine');
+const build = require('../build');
 const config = require('../config');
 
-module.exports = function test() {
+/**
+ * Run unit tests and exit.
+ *
+ * @return {WritableStream} The gulp pipe stream.
+ */
+function test() {
   const src = [
     path.join(config.test, 'base.spec.js'),
     path.join(config.test, '**', '*.spec.js'),
   ];
 
   return gulp.src(src).pipe(jasmine());
+}
+
+/**
+ * Watch files and run unit test suite every time a change is detected.
+ *
+ * @param {function} done The `done` function.
+ * @return {void}
+ */
+function tdd(done) {
+  gulp.watch(path.join(config.dist, '**', '*.js'), test);
+  gulp.watch(path.join(config.src, '**', '*.js'), build);
+  gulp.watch(path.join(config.test, '**', '*.js'), test);
+
+  done();
+}
+
+module.exports = {
+  tdd,
+  test,
 };
+