blog/test/linked-articles.test.js

import test from "node:test";
import assert from "node:assert/strict";
import fs from "node:fs";
import path from "node:path";
import { resolveLinkedArticles, validateLinkedArticles } from "../src/_utils/linked-articles.js";
import { filters } from "../src/_filters/index.js";
import configureEleventy from "../eleventy.config.js";

test("Linked articles: accepts an article's list when every name identifies another post", () => {
  assert.doesNotThrow(() => {
    validateLinkedArticles([
      {
        inputPath: "src/posts/2026-10-06-terminal-preview-demo.md",
        data: {
          title: "Terminal Preview Demo",
          linkedArticles: ["Markdown Preview Demo"]
        }
      },
      {
        inputPath: "src/posts/2026-10-05-markdown-preview-demo.md",
        data: { title: "Markdown Preview Demo" }
      }
    ]);
  });
});

test("Linked articles: rejects a non-list frontmatter value", () => {
  assert.throws(
    () => {
      validateLinkedArticles([
        {
          inputPath: "src/posts/2026-10-06-terminal-preview-demo.md",
          data: {
            title: "Terminal Preview Demo",
            linkedArticles: "Markdown Preview Demo"
          }
        },
        {
          inputPath: "src/posts/2026-10-05-markdown-preview-demo.md",
          data: { title: "Markdown Preview Demo" }
        }
      ]);
    },
    /must define 'linkedArticles' as a YAML list/
  );
});

test("Linked articles: rejects empty and unknown article names", () => {
  const posts = [
    {
      inputPath: "src/posts/2026-10-06-terminal-preview-demo.md",
      data: { title: "Terminal Preview Demo", linkedArticles: [""] }
    },
    {
      inputPath: "src/posts/2026-10-05-markdown-preview-demo.md",
      data: { title: "Markdown Preview Demo" }
    }
  ];

  assert.throws(() => validateLinkedArticles(posts), /non-empty article titles/);

  posts[0].data.linkedArticles = ["Missing Dispatch"];
  assert.throws(() => validateLinkedArticles(posts), /links to unknown article 'Missing Dispatch'/);
});

test("Linked articles: rejects self-references and duplicate navigation targets", () => {
  const posts = [
    {
      inputPath: "src/posts/2026-10-06-terminal-preview-demo.md",
      data: {
        title: "Terminal Preview Demo",
        linkedArticles: ["Terminal Preview Demo"]
      }
    },
    {
      inputPath: "src/posts/2026-10-05-markdown-preview-demo.md",
      data: { title: "Markdown Preview Demo" }
    }
  ];

  assert.throws(() => validateLinkedArticles(posts), /cannot link to itself/);

  posts[0].data.linkedArticles = ["Markdown Preview Demo", "Markdown Preview Demo"];
  assert.throws(() => validateLinkedArticles(posts), /cannot contain duplicate article titles/);
});

test("Linked articles: the Eleventy posts collection rejects invalid frontmatter", () => {
  const collections = new Map();
  configureEleventy({
    setUseGitIgnore() {},
    addPassthroughCopy() {},
    addPlugin() {},
    setLibrary() {},
    addFilter() {},
    addCollection(name, callback) {
      collections.set(name, callback);
    },
    setServerOptions() {}
  });

  assert.throws(
    () => {
      collections.get("posts")({
        getFilteredByGlob() {
          return [
            {
              inputPath: "src/posts/2026-10-06-terminal-preview-demo.md",
              data: {
                title: "Terminal Preview Demo",
                linkedArticles: ["Missing Dispatch"]
              }
            }
          ];
        }
      });
    },
    /links to unknown article 'Missing Dispatch'/
  );
});

test("Linked articles: resolves named posts in the frontmatter order for navigation", () => {
  const posts = [
    {
      url: "/dispatches/terminal-preview-demo/",
      data: { title: "Terminal Preview Demo" }
    },
    {
      url: "/dispatches/markdown-preview-demo/",
      data: { title: "Markdown Preview Demo" }
    }
  ];

  assert.deepEqual(
    resolveLinkedArticles(posts, ["Markdown Preview Demo", "Terminal Preview Demo"]),
    [posts[1], posts[0]]
  );
});

test("Linked articles: exposes navigation resolution to Nunjucks", () => {
  assert.strictEqual(filters.resolveLinkedArticles, resolveLinkedArticles);
});

test("Linked articles: post layout renders Other Articles at the top of dispatch telemetry", () => {
  const postLayout = fs.readFileSync(
    path.resolve("src/_includes/layouts/post.njk"),
    "utf-8"
  );

  assert.match(
    postLayout,
    /{% set linkedPosts = collections\.posts \| resolveLinkedArticles\(linkedArticles\) %}[\s\S]*?<div[^>]+class="sidebar-heading">OTHER ARTICLES<\/div>[\s\S]*?<nav[^>]+aria-label="Other Articles">[\s\S]*?href="{{ linkedPost\.url }}"/
  );
});