diff --git a/packages/builder/.gitignore b/packages/builder/.gitignore
new file mode 100644
index 00000000..567609b1
--- /dev/null
+++ b/packages/builder/.gitignore
@@ -0,0 +1 @@
+build/
diff --git a/packages/builder/test/index.test.js b/packages/builder/test/index.test.js
new file mode 100644
index 00000000..60e21947
--- /dev/null
+++ b/packages/builder/test/index.test.js
@@ -0,0 +1,16 @@
+const path = require('path');
+const fs = require('fs');
+const { build } = require('../src');
+
+afterEach(() => {
+  fs.rmSync(path.resolve(__dirname, '..', 'build'), { recursive: true });
+});
+
+test('It can build a radar', async () => {
+  const outputFile = path.resolve(__dirname, '..', 'build', 'js', 'radar.json');
+  await build(
+    path.resolve(__dirname, 'radar', 'valid'),
+    outputFile,
+  );
+  expect(fs.existsSync(outputFile)).toEqual(true);
+});