DEV: Move discourse-chat to the core repo. (#18776)

As part of this move, we are also renaming `discourse-chat` to `chat`.

plugins/chat/test/javascripts/components/collapser-test.js

@@ -0,0 +1,45 @@
+import componentTest, {
+  setupRenderingTest,
+} from "discourse/tests/helpers/component-test";
+import { click } from "@ember/test-helpers";
+import hbs from "htmlbars-inline-precompile";
+import { exists, query, visible } from "discourse/tests/helpers/qunit-helpers";
+import { module } from "qunit";
+import { htmlSafe } from "@ember/template";
+
+module("Discourse Chat | Component | collapser", function (hooks) {
+  setupRenderingTest(hooks);
+
+  componentTest("renders header", {
+    template: hbs`{{collapser header=header}}`,
+
+    beforeEach() {
+      this.set("header", htmlSafe("<div class='cat'>tomtom</div>"));
+    },
+
+    async test(assert) {
+      const element = query(".cat");
+
+      assert.ok(exists(element));
+    },
+  });
+
+  componentTest("collapses and expands yielded body", {
+    template: hbs`{{#collapser}}<div class='cat'>body text</div>{{/collapser}}`,
+
+    test: async function (assert) {
+      const openButton = ".chat-message-collapser-closed";
+      const closeButton = ".chat-message-collapser-opened";
+      const body = ".cat";
+
+      assert.ok(visible(body));
+      await click(closeButton);
+
+      assert.notOk(visible(body));
+
+      await click(openButton);
+
+      assert.ok(visible(body));
+    },
+  });
+});