Add tests for oneboxer.js.es6 (#8418)

test/javascripts/lib/oneboxer-test.js.es6

@@ -0,0 +1,78 @@
+import { load } from "pretty-text/oneboxer";
+import { ajax } from "discourse/lib/ajax";
+import { failedCache, localCache } from "pretty-text/oneboxer-cache";
+import { stringToHTML } from "helpers/html-helper";
+
+function loadOnebox(element) {
+  return load({
+    elem: element,
+    refresh: false,
+    ajax,
+    synchronous: true,
+    categoryId: 1,
+    topicId: 1
+  });
+}
+
+QUnit.module("lib:oneboxer");
+
+QUnit.test("load - failed onebox", async assert => {
+  let element = document.createElement("A");
+  element.setAttribute("href", "http://somebadurl.com");
+
+  // prettier-ignore
+  server.get("/onebox", () => { //eslint-disable-line
+    return [404, {}, {}];
+  });
+
+  await loadOnebox(element);
+
+  assert.equal(
+    failedCache["http://somebadurl.com"],
+    true,
+    "stores the url as failed in a cache"
+  );
+  assert.equal(
+    loadOnebox(element),
+    undefined,
+    "it returns early for a failed cache"
+  );
+});
+
+QUnit.test("load - successful onebox", async assert => {
+  const html = `
+    <aside class="onebox whitelistedgeneric">
+      <header class="source">
+          <a href="http://test.com/somepage" target="_blank">test.com</a>
+      </header>
+      <article class="onebox-body">
+      <div class="aspect-image" style="--aspect-ratio:690/362;"><img src="https://test.com/image.png" class="thumbnail"></div>
+      <h3><a href="http://test.com/somepage" target="_blank">Test Page</a></h3>
+      <p>Yet another collaboration tool</p>
+      </article>
+      <div class="onebox-metadata"></div>
+      <div style="clear: both"></div>
+    </aside>
+  `;
+
+  // prettier-ignore
+  server.get("/onebox", () => { //eslint-disable-line
+    return [200, {}, html];
+  });
+
+  let element = document.createElement("A");
+  element.setAttribute("href", "http://somegoodurl.com");
+
+  await loadOnebox(element);
+
+  assert.equal(
+    localCache["http://somegoodurl.com"].prop("outerHTML"),
+    stringToHTML(html).outerHTML,
+    "stores the html of the onebox in a local cache"
+  );
+  assert.equal(
+    loadOnebox(element),
+    stringToHTML(html).outerHTML,
+    "it returns the html from the cache"
+  );
+});