Unit test: UndoManager

.vscode/launch.json

@@ -20,6 +20,35 @@
 				"<node_internals>/**"
 			],
 			"type": "pwa-node"
-		}
+		},
+        {
+            "type": "node",
+            "request": "launch",
+            "name": "Jest: run all tests",
+            "program": "${workspaceRoot}/webapp/node_modules/jest/bin/jest.js",
+            "cwd": "${workspaceRoot}/webapp",
+            "args": [
+              "--verbose",
+              "-i",
+              "--no-cache"
+            ],
+            "console": "integratedTerminal",
+            "internalConsoleOptions": "neverOpen"
+          },
+          {
+            "type": "node",
+            "request": "launch",
+            "name": "Jest: run current file",
+            "program": "${workspaceRoot}/webapp/node_modules/jest/bin/jest.js",
+            "cwd": "${workspaceRoot}/webapp",
+            "args": [
+                "${fileBasename}",
+                "--verbose",
+                "-i",
+                "--no-cache",
+              ],
+            "console": "integratedTerminal",
+            "internalConsoleOptions": "neverOpen"
+          },
     ]
 }

webapp/src/undoManager.test.ts

@@ -0,0 +1,46 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import undoManager from './undomanager'
+import {Utils} from './utils'
+
+test('Basic undo/redo', async () => {
+    expect(!undoManager.canUndo).toBe(true)
+    expect(!undoManager.canRedo).toBe(true)
+
+    const values: string[] = []
+
+    await undoManager.perform(
+        async () => {
+            values.push('a')
+        },
+        async () => {
+            values.pop()
+        },
+        'test',
+    )
+
+    expect(undoManager.canUndo).toBe(true)
+    expect(undoManager.canRedo).toBe(false)
+    expect(Utils.arraysEqual(values, ['a'])).toBe(true)
+    expect(undoManager.undoDescription).toBe('test')
+    expect(undoManager.redoDescription).toBe(undefined)
+
+    await undoManager.undo()
+    expect(undoManager.canUndo).toBe(false)
+    expect(undoManager.canRedo).toBe(true)
+    expect(Utils.arraysEqual(values, [])).toBe(true)
+    expect(undoManager.undoDescription).toBe(undefined)
+    expect(undoManager.redoDescription).toBe('test')
+
+    await undoManager.redo()
+    expect(undoManager.canUndo).toBe(true)
+    expect(undoManager.canRedo).toBe(false)
+    expect(Utils.arraysEqual(values, ['a'])).toBe(true)
+
+    await undoManager.clear()
+    expect(undoManager.canUndo).toBe(false)
+    expect(undoManager.canRedo).toBe(false)
+    expect(undoManager.undoDescription).toBe(undefined)
+    expect(undoManager.redoDescription).toBe(undefined)
+})