// tests/unit/chatcore-executor-client-headers.test.ts
// Characterization of buildExecutorClientHeaders — the executor client-header normalizer extracted
// from handleChatCore (chatCore god-file decomposition, #3501). Locks: Headers and plain-object
// normalization, non-string value skipping, User-Agent backfill (both casings, only when absent),
// and the null-when-empty return.
import { test } from "node:test";
import assert from "node:assert/strict";
import { buildExecutorClientHeaders } from "../../open-sse/handlers/chatCore/executorClientHeaders.ts";

test("returns null for empty / nullish inputs", () => {
  assert.equal(buildExecutorClientHeaders(null), null);
  assert.equal(buildExecutorClientHeaders(undefined), null);
  assert.equal(buildExecutorClientHeaders({}), null);
});

test("normalizes a Headers instance", () => {
  const h = new Headers({ "X-Test": "1", "content-type": "application/json" });
  const out = buildExecutorClientHeaders(h);
  assert.equal(out?.["content-type"], "application/json");
  assert.equal(out?.["x-test"], "1");
});

test("normalizes a plain object and skips non-string values", () => {
  const out = buildExecutorClientHeaders({ a: "1", b: 2, c: null } as Record<string, unknown>);
  assert.deepEqual(out, { a: "1" });
});

test("backfills the User-Agent in both casings when absent", () => {
  const out = buildExecutorClientHeaders({ a: "1" }, "  MyAgent/1.0  ");
  assert.equal(out?.["user-agent"], "MyAgent/1.0");
  assert.equal(out?.["User-Agent"], "MyAgent/1.0");
});

test("does not overwrite an existing user-agent header", () => {
  const out = buildExecutorClientHeaders({ "user-agent": "Existing/9" }, "MyAgent/1.0");
  assert.equal(out?.["user-agent"], "Existing/9");
  assert.equal(out?.["User-Agent"], undefined);
});

test("a trimmed-empty user agent does not create headers on its own", () => {
  assert.equal(buildExecutorClientHeaders({}, "   "), null);
});