1 files changed, 49 insertions, 0 deletions
diff --git a/tiny-invariant/test/bundle-size.spec.js b/tiny-invariant/test/bundle-size.spec.js
new file mode 100644
index 0000000..314e41a
--- /dev/null
+++ b/tiny-invariant/test/bundle-size.spec.js
@@ -0,0 +1,49 @@
+// @flow
+import { rollup } from 'rollup';
+import babel from 'rollup-plugin-babel';
+import replace from 'rollup-plugin-replace';
+
+const DEV_SIZE = 201;
+const PROD_SIZE = 176;
+
+const getCode = async ({ mode }): Promise<string> => {
+  const bundle = await rollup({
+    input: './src/index.js',
+    plugins: [
+      replace({ 'process.env.NODE_ENV': JSON.stringify(mode) }),
+      babel(),
+    ],
+  });
+  const { code } = await bundle.generate({ format: 'esm' });
+  return code;
+};
+
+it(`development mode size should be ${DEV_SIZE}`, async () => {
+  const code: string = await getCode({ mode: 'development' });
+  expect(code.length).toBe(DEV_SIZE);
+});
+
+it(`production mode size should be ${PROD_SIZE}`, async () => {
+  const code: string = await getCode({ mode: 'production' });
+  expect(code.length).toBe(PROD_SIZE);
+});
+
+const containsDevCode = (code: string) => {
+  return code.includes(`throw new Error(prefix + ": " + (message || ''))`);
+};
+
+const containsProdCode = (code: string) => {
+  return code.includes(`throw new Error(prefix)`);
+};
+
+it('should include the message in dev builds', async () => {
+  const code: string = await getCode({ mode: 'development' });
+  expect(containsDevCode(code)).toBe(true);
+  expect(containsProdCode(code)).toBe(false);
+});
+
+it('not should include the message in prod builds', async () => {
+  const code: string = await getCode({ mode: 'production' });
+  expect(containsDevCode(code)).toBe(false);
+  expect(containsProdCode(code)).toBe(true);
+});