1 files changed, 35 insertions, 0 deletions
diff --git a/@linaria/packages/react/__tests__/detect-core-js.test.js b/@linaria/packages/react/__tests__/detect-core-js.test.js
new file mode 100644
index 0000000..22bfbe4
--- /dev/null
+++ b/@linaria/packages/react/__tests__/detect-core-js.test.js
@@ -0,0 +1,35 @@
+import cp from 'child_process';
+
+const waitForProcess = async (process) => {
+  return new Promise((resolve) => {
+    let output = '';
+    process.stdout.on('data', (chunk) => {
+      output += chunk.toString();
+    });
+    process.on('close', () => {
+      resolve(output);
+    });
+  });
+};
+
+it('Ensures that package do not include core-js dependency after build', async () => {
+  // eslint-disable-next-line import/no-extraneous-dependencies
+  const packageJSON = require('@linaria/babel-preset/package.json');
+  const buildScript = packageJSON.scripts['build:lib'];
+
+  const proc = cp.exec(buildScript, {
+    stdio: 'ignore',
+    env: {
+      ...process.env,
+      DEBUG_CORE_JS: 'true',
+    },
+  });
+  const result = await waitForProcess(proc);
+  // run `DEBUG_CORE_JS=true yarn build:lib` to debug issues with introduced core-js dependency
+  expect(result).not.toContain(
+    'The corejs3 polyfill added the following polyfills'
+  );
+  expect(result).toContain(
+    'Based on your code and targets, the corejs3 polyfill did not add any polyfill'
+  );
+}, 15000);