Increase coverage (#1997)

## Launch Checklist

This PR increases coverage by adding unit tests to lib folde, replace
the skipped end to end placeholder with actual tests and adds more end
to end tests.

This was mostly done by AI (Claude opus 4.8) and I reviewed it and
requested changes where needed.

 - [x] Briefly describe the changes in this PR.
 - [x] Link to related issues.
- [x] Include before/after visuals or gifs if this PR includes visual
changes.
 - [x] Write tests for all new functionality.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

e2e/access-tokens.spec.ts

@@ -0,0 +1,60 @@
+import { test, expect, describe, beforeEach } from "./utils/fixtures";
+import { MaputnikDriver } from "./maputnik-driver";
+import tokens from "../src/config/tokens.json" with { type: "json" };
+
+describe("access tokens", () => {
+  const { given, when } = new MaputnikDriver();
+
+  const tileJson = {
+    tilejson: "2.2.0",
+    tiles: ["https://example.local/{z}/{x}/{y}.pbf"],
+    minzoom: 0,
+    maxzoom: 14,
+  };
+
+  beforeEach(async () => {
+    await given.setupMockBackedResponses();
+  });
+
+  test("uses the thunderforest token for a thunderforest source", async () => {
+    await given.interceptAndMockResponse({
+      method: "GET",
+      url: /tile\.thunderforest\.com\/.*/,
+      response: tileJson,
+      alias: "thunderforest",
+    });
+
+    await when.setStyle("access_tokens");
+
+    const request = await when.waitForResponse("thunderforest");
+    expect(request.url()).toContain(`apikey=${tokens.thunderforest}`);
+  });
+
+  test("uses the locationiq token for a locationiq source", async () => {
+    await given.interceptAndMockResponse({
+      method: "GET",
+      url: /tiles\.locationiq\.com\/.*/,
+      response: tileJson,
+      alias: "locationiq",
+    });
+
+    await when.setStyle("access_tokens");
+
+    const request = await when.waitForResponse("locationiq");
+    expect(request.url()).toContain(`key=${tokens.locationiq}`);
+  });
+
+  test("appends the stadia token as a query parameter", async () => {
+    await given.interceptAndMockResponse({
+      method: "GET",
+      url: /tiles\.stadiamaps\.com\/.*/,
+      response: tileJson,
+      alias: "stadia",
+    });
+
+    await when.setStyle("access_tokens");
+
+    const request = await when.waitForResponse("stadia");
+    expect(request.url()).toContain("?api_key=stadia-test-token");
+  });
+});