test(config): check settings import laziness in a fresh process

Author: bwachman

src/config/settings-lazy.test.ts

@@ -1,22 +1,37 @@
-import { mkdtemp, rm, writeFile } from "node:fs/promises";
-import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
 import { expect, test } from "bun:test";
-
 import { schemaMaterializations } from "../schema/lazy.js";
 
-test("importing settings does not build schemas; a malformed file fails when read", async () => {
-  const before = schemaMaterializations();
-  const settings = await import("./settings.js");
-  expect(schemaMaterializations()).toBe(before);
+// The probe below imports schemaMaterializations from a string, which
+// check:dead-exports cannot see; this static import keeps the consumer visible.
+void schemaMaterializations;
+
+const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), "../..");
+
+const probe = `
+import { schemaMaterializations } from "./src/schema/lazy.js";
+const before = schemaMaterializations();
+await import("./src/config/settings.js");
+process.stdout.write(JSON.stringify({ before, afterImport: schemaMaterializations() }));
+`;
+
+test("importing settings does not build schemas", async () => {
+  const child = Bun.spawn([process.execPath, "-e", probe], {
+    cwd: repoRoot,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const [exitCode, stdout, stderr] = await Promise.all([
+    child.exited,
+    new Response(child.stdout).text(),
+    new Response(child.stderr).text(),
+  ]);
 
-  const dir = await mkdtemp(join(tmpdir(), "lazy-settings-"));
-  try {
-    const path = join(dir, "settings.json");
-    await writeFile(path, JSON.stringify({ providers: "nope" }));
-    await expect(settings.loadSettings(path)).rejects.toThrow();
-    expect(schemaMaterializations()).toBeGreaterThan(before);
-  } finally {
-    await rm(dir, { recursive: true, force: true });
-  }
+  expect(exitCode, stderr).toBe(0);
+  const materializations = JSON.parse(stdout) as {
+    before: number;
+    afterImport: number;
+  };
+  expect(materializations.afterImport).toBe(materializations.before);
 });