diff --git a/package.json b/package.json
index 852e13e..75c2ea3 100644
--- a/package.json
+++ b/package.json
@@ -12,15 +12,18 @@
     "prepare": "npm run -s build",
     "prepare:babel": "babel --presets env src/*.js -d dist && npm t",
     "lint": "eslint src",
-    "test:build": "node dist/cli.js --no-compress --cwd test/demo",
-    "test:build:ts": "node dist/cli.js --no-compress --cwd test/ts-demo --entry=src/index.ts",
-    "test": "npm run -s lint && npm run -s build && npm run -s test:build && npm run -s test:build:ts",
+    "test": "npm run -s lint && npm run -s build && jest",
     "release": "npm run -s prepare && npm test && git commit -am $npm_package_version && git tag $npm_package_version && git push && git push --tags && npm publish"
   },
   "repository": "developit/microbundle",
   "eslintConfig": {
     "extends": "eslint-config-developit"
   },
+  "babel": {
+    "presets": [
+      "env"
+    ]
+  },
   "keywords": [
     "bundle",
     "rollup",
@@ -66,6 +69,9 @@
     "babel-cli": "^6.26.0",
     "babel-preset-env": "^1.6.1",
     "eslint": "^4.15.0",
-    "eslint-config-developit": "^1.1.1"
+    "eslint-config-developit": "^1.1.1",
+    "fs-extra": "^5.0.0",
+    "jest": "^22.1.4",
+    "strip-ansi": "^4.0.0"
   }
 }
diff --git a/src/index.js b/src/index.js
index effcde5..b395106 100644
--- a/src/index.js
+++ b/src/index.js
@@ -6,6 +6,7 @@ import promisify from 'es6-promisify';
 import glob from 'glob';
 import autoprefixer from 'autoprefixer';
 import { rollup, watch } from 'rollup';
+import acornJsx from 'acorn-jsx';
 import nodent from 'rollup-plugin-nodent';
 import commonjs from 'rollup-plugin-commonjs';
 import nodeResolve from 'rollup-plugin-node-resolve';
@@ -33,26 +34,32 @@ const WATCH_OPTS = {
 };
 
 export default async function microbundle(options) {
-	let cwd = options.cwd = resolve(process.cwd(), options.cwd);
+	let cwd = options.cwd = resolve(process.cwd(), options.cwd),
+		hasPackageJson = true;
 
 	try {
 		options.pkg = JSON.parse(await readFile(resolve(cwd, 'package.json'), 'utf8'));
 	}
 	catch (err) {
-		console.warn(chalk.yellow(`${chalk.yellow.inverse('WARN')} no package.json found.`));
+		process.stderr.write(chalk.yellow(`${chalk.yellow.inverse('WARN')} no package.json found. Assuming a name of "${basename(options.cwd)}".`)+'\n');
 		let msg = String(err.message || err);
 		if (!msg.match(/ENOENT/)) console.warn(`  ${chalk.red.dim(msg)}`);
 		options.pkg = {};
+		hasPackageJson = false;
 	}
 
 	if (!options.pkg.name) {
 		options.pkg.name = basename(options.cwd);
-		console.warn(chalk.yellow(`${chalk.yellow.inverse('WARN')} missing package.json "name" field. Assuming "${options.pkg.name}".`));
+		if (hasPackageJson) {
+			process.stderr.write(chalk.yellow(`${chalk.yellow.inverse('WARN')} missing package.json "name" field. Assuming "${options.pkg.name}".`)+'\n');
+		}
 	}
 
+	const jsOrTs = async filename => resolve(cwd, `${filename}${await isFile(resolve(cwd, filename+'.ts')) ? '.ts' : '.js'}`);
+
 	options.input = [];
 	[].concat(
-		options.entries && options.entries.length ? options.entries : options.pkg.source || (await isDir(resolve(cwd, 'src')) && 'src/index.js') || (await isFile(resolve(cwd, 'index.js')) && 'index.js') || options.pkg.module
+		options.entries && options.entries.length ? options.entries : options.pkg.source || (await isDir(resolve(cwd, 'src')) && await jsOrTs('src/index')) || await jsOrTs('index') || options.pkg.module
 	).map( file => glob.sync(resolve(cwd, file)) ).forEach( file => options.input.push(...file) );
 
 	let main = resolve(cwd, options.output || options.pkg.main || 'dist');
@@ -217,7 +224,7 @@ function createConfig(options, entry, format, writeMeta) {
 					},
 					parser: {
 						plugins: {
-							jsx: require('acorn-jsx')
+							jsx: acornJsx
 						}
 					}
 				}),
diff --git a/test/demo.test.js b/test/demo.test.js
new file mode 100644
index 0000000..4365d22
--- /dev/null
+++ b/test/demo.test.js
@@ -0,0 +1,31 @@
+import path from 'path';
+import fs from 'fs-extra';
+import { strip } from './lib/util';
+import microbundle from '../src/index';
+
+describe('demo', () => {
+	it('should produce build files', async () => {
+		let output = await microbundle({
+			cwd: path.resolve(__dirname, 'fixtures/demo'),
+			formats: 'es,cjs,umd'
+		});
+
+		expect(strip(output)).toEqual(strip(`
+			Build output to dist:
+			225 B: demo.js
+			225 B: demo.m.js
+			295 B: demo.umd.js
+		`));
+
+		let dist = await fs.readdir(path.resolve(__dirname, 'fixtures/demo/dist'));
+
+		expect(dist).toEqual([
+			'demo.js',
+			'demo.js.map',
+			'demo.m.js',
+			'demo.m.js.map',
+			'demo.umd.js',
+			'demo.umd.js.map'
+		]);
+	});
+});
diff --git a/test/demo/src/index.js b/test/fixtures/demo/src/index.js
similarity index 100%
rename from test/demo/src/index.js
rename to test/fixtures/demo/src/index.js
diff --git a/test/demo/src/two.js b/test/fixtures/demo/src/two.js
similarity index 100%
rename from test/demo/src/two.js
rename to test/fixtures/demo/src/two.js
diff --git a/test/ts-demo/src/car.ts b/test/fixtures/ts-demo/src/car.ts
similarity index 100%
rename from test/ts-demo/src/car.ts
rename to test/fixtures/ts-demo/src/car.ts
diff --git a/test/ts-demo/src/index.ts b/test/fixtures/ts-demo/src/index.ts
similarity index 100%
rename from test/ts-demo/src/index.ts
rename to test/fixtures/ts-demo/src/index.ts
diff --git a/test/lib/util.js b/test/lib/util.js
new file mode 100644
index 0000000..46debd9
--- /dev/null
+++ b/test/lib/util.js
@@ -0,0 +1,3 @@
+import stripAnsi from 'strip-ansi';
+
+export const strip = s => stripAnsi(s).replace(/(?:^[\n\s]+|[\n\s]+$|(^|\n)\s+)/gm, '$1');
diff --git a/test/ts-demo.test.js b/test/ts-demo.test.js
new file mode 100644
index 0000000..445a027
--- /dev/null
+++ b/test/ts-demo.test.js
@@ -0,0 +1,31 @@
+import path from 'path';
+import fs from 'fs-extra';
+import { strip } from './lib/util';
+import microbundle from '../src/index';
+
+describe('ts-demo', () => {
+	it('should produce build files', async () => {
+		let output = await microbundle({
+			cwd: path.resolve(__dirname, 'fixtures/ts-demo'),
+			formats: 'es,cjs,umd'
+		});
+
+		expect(strip(output)).toEqual(strip(`
+			Build output to dist:
+			106 B: ts-demo.js
+			106 B: ts-demo.m.js
+			175 B: ts-demo.umd.js
+		`));
+
+		let dist = await fs.readdir(path.resolve(__dirname, 'fixtures/ts-demo/dist'));
+
+		expect(dist).toEqual([
+			'ts-demo.js',
+			'ts-demo.js.map',
+			'ts-demo.m.js',
+			'ts-demo.m.js.map',
+			'ts-demo.umd.js',
+			'ts-demo.umd.js.map'
+		]);
+	});
+});
diff --git a/test/ts-demo/package.json b/test/ts-demo/package.json
deleted file mode 100644
index 3a020c0..0000000
--- a/test/ts-demo/package.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "name": "ts-demo"
-}