diff --git a/tests/shell/oai-spec-test.test.mjs b/tests/shell/oai-spec-test.test.mjs
new file mode 100644
index 0000000..c4c62e8
--- /dev/null
+++ b/tests/shell/oai-spec-test.test.mjs
@@ -0,0 +1,49 @@
+import { execFileSync } from "node:child_process";
+import { chmodSync, cpSync, mkdtempSync, mkdirSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { dirname, join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+import { afterEach, describe, expect, test } from "vitest";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const packageRoot = resolve(__dirname, "../..");
+const testDirs = [];
+
+afterEach(() => {
+  while (testDirs.length > 0) {
+    rmSync(testDirs.pop(), { recursive: true, force: true });
+  }
+});
+
+describe("oai-spec-test", () => {
+  test("runs c8 and vitest from a package checkout layout", () => {
+    const fixture = createPackageCheckoutFixture();
+
+    const output = execFileSync(join(fixture, "bin/oai-spec-test"), ["--runInBand"], {
+      cwd: fixture,
+      encoding: "utf8"
+    });
+
+    expect(output).toContain("c8 --100");
+    expect(output).toContain("vitest/vitest.mjs run --coverage --runInBand");
+  });
+});
+
+function createPackageCheckoutFixture() {
+  const root = mkdtempSync(join(tmpdir(), "oai-spec-test-checkout-"));
+  testDirs.push(root);
+
+  mkdirSync(join(root, "bin"), { recursive: true });
+  cpSync(join(packageRoot, "bin/oai-spec-test"), join(root, "bin/oai-spec-test"));
+  chmodSync(join(root, "bin/oai-spec-test"), 0o755);
+
+  mkdirSync(join(root, "node_modules/c8/bin"), { recursive: true });
+  writeFileSync(join(root, "node_modules/c8/package.json"), JSON.stringify({ name: "c8", version: "0.0.0" }));
+  writeFileSync(join(root, "node_modules/c8/bin/c8.js"), "console.log(`c8 ${process.argv.slice(2).join(' ')}`);\n");
+
+  mkdirSync(join(root, "node_modules/vitest"), { recursive: true });
+  writeFileSync(join(root, "node_modules/vitest/package.json"), JSON.stringify({ name: "vitest", version: "0.0.0" }));
+  writeFileSync(join(root, "node_modules/vitest/vitest.mjs"), "console.log('vitest fixture');\n");
+
+  return root;
+}