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/chat-composer-placeholder-test.js

@@ -0,0 +1,87 @@
+import { set } from "@ember/object";
+import componentTest, {
+  setupRenderingTest,
+} from "discourse/tests/helpers/component-test";
+import { query } from "discourse/tests/helpers/qunit-helpers";
+import hbs from "htmlbars-inline-precompile";
+import ChatChannel from "discourse/plugins/chat/discourse/models/chat-channel";
+import { module } from "qunit";
+
+module(
+  "Discourse Chat | Component | chat-composer placeholder",
+  function (hooks) {
+    setupRenderingTest(hooks);
+
+    componentTest("direct message to self shows Jot something down", {
+      template: hbs`{{chat-composer chatChannel=chatChannel}}`,
+
+      beforeEach() {
+        set(this.currentUser, "id", 1);
+        this.set(
+          "chatChannel",
+          ChatChannel.create({
+            chatable_type: "DirectMessageChannel",
+            chatable: {
+              users: [{ id: 1 }],
+            },
+          })
+        );
+      },
+
+      async test(assert) {
+        assert.equal(
+          query(".chat-composer-input").placeholder,
+          "Jot something down"
+        );
+      },
+    });
+
+    componentTest("direct message to multiple folks shows their names", {
+      template: hbs`{{chat-composer chatChannel=chatChannel}}`,
+
+      beforeEach() {
+        this.set(
+          "chatChannel",
+          ChatChannel.create({
+            chatable_type: "DirectMessageChannel",
+            chatable: {
+              users: [
+                { name: "Tomtom" },
+                { name: "Steaky" },
+                { username: "zorro" },
+              ],
+            },
+          })
+        );
+      },
+
+      async test(assert) {
+        assert.equal(
+          query(".chat-composer-input").placeholder,
+          "Chat with Tomtom, Steaky, @zorro"
+        );
+      },
+    });
+
+    componentTest("message to channel shows send message to channel name", {
+      template: hbs`{{chat-composer chatChannel=chatChannel}}`,
+
+      beforeEach() {
+        this.set(
+          "chatChannel",
+          ChatChannel.create({
+            chatable_type: "Category",
+            title: "just-cats",
+          })
+        );
+      },
+
+      async test(assert) {
+        assert.equal(
+          query(".chat-composer-input").placeholder,
+          "Chat with #just-cats"
+        );
+      },
+    });
+  }
+);