diff --git a/scripts/utils.test.js b/scripts/utils.test.js
new file mode 100644
index 00000000..8f6fc911
--- /dev/null
+++ b/scripts/utils.test.js
@@ -0,0 +1,52 @@
+const test = require('node:test');
+const assert = require('node:assert');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const { listModelFiles } = require('./utils.js');
+
+test('utils.js', async (t) => {
+  let tmpDir;
+
+  t.beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'bionetgen-utils-test-'));
+  });
+
+  t.afterEach(() => {
+    if (tmpDir) {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  });
+
+  await t.test('listModelFiles returns only .bngl files in alphabetical order', () => {
+    fs.writeFileSync(path.join(tmpDir, 'model2.bngl'), 'content');
+    fs.writeFileSync(path.join(tmpDir, 'model1.bngl'), 'content');
+    fs.writeFileSync(path.join(tmpDir, 'model3.bngl'), 'content');
+
+    const files = listModelFiles(tmpDir);
+    assert.deepStrictEqual(files, ['model1.bngl', 'model2.bngl', 'model3.bngl']);
+  });
+
+  await t.test('listModelFiles ignores directories even if named with .bngl extension', () => {
+    fs.writeFileSync(path.join(tmpDir, 'model1.bngl'), 'content');
+    fs.mkdirSync(path.join(tmpDir, 'dir.bngl'));
+    fs.mkdirSync(path.join(tmpDir, 'other-dir'));
+
+    const files = listModelFiles(tmpDir);
+    assert.deepStrictEqual(files, ['model1.bngl']);
+  });
+
+  await t.test('listModelFiles ignores files with other extensions', () => {
+    fs.writeFileSync(path.join(tmpDir, 'model1.bngl'), 'content');
+    fs.writeFileSync(path.join(tmpDir, 'data.txt'), 'content');
+    fs.writeFileSync(path.join(tmpDir, 'model2.xml'), 'content');
+
+    const files = listModelFiles(tmpDir);
+    assert.deepStrictEqual(files, ['model1.bngl']);
+  });
+
+  await t.test('listModelFiles returns empty array for empty directory', () => {
+    const files = listModelFiles(tmpDir);
+    assert.deepStrictEqual(files, []);
+  });
+});