Write integration tests (#719)

* Scaffold a simple test case for debugging

* Set up Jest environment that works with React

- Install and set up react-testing-library
- "Unignore" roughjs and browser-nativejs transformations
- Separate App component from ReactDOM

* Write first passing test

- Mock canvas
- Remove App file and mount/unmount ReactDOM on import

* Add tests for drag create behavior

* Fix comments in dragCreate

* Pin jest-mock-canvas dependency

* Remove dependency range for testing library

* Add tests for multi point mode and selection element

* Fix all tests due to decrease in updates to canvas when changing tools

* Disable state updates if component is unmounted

- Remove all event listeners
- Disable storing scene in state if component is unmounted

* Add tests for move and element selection

* Merge branch 'master' into add-integration-tests

* Add tests for resizing rectangle

* move unmounted check to syncActionResult method

* Use a custom test renderer instead of default testing-library functions

* Add custom query for selecting tools

* move files around

Co-authored-by: David Luzar <luzar.david@gmail.com>

src/setupTests.ts

@@ -0,0 +1,8 @@
+import "@testing-library/jest-dom";
+import "jest-canvas-mock";
+
+// ReactDOM is located inside index.tsx file
+// as a result, we need a place for it to render into
+const element = document.createElement("div");
+element.id = "root";
+document.body.appendChild(element);