Add tests for AircraftLayer.

client/src/testutils/index.tsx

@@ -0,0 +1,30 @@
+// https://redux.js.org/usage/writing-tests
+import { setupStore } from "../app/store";
+import type { AppStore, RootState } from "../app/store";
+import type { PreloadedState } from "@reduxjs/toolkit";
+import { render } from "@testing-library/react";
+import type { RenderOptions } from "@testing-library/react";
+import React, { PropsWithChildren } from "react";
+import { Provider } from "react-redux";
+
+// This type interface extends the default options for render from RTL, as well
+// as allows the user to specify other things such as initialState, store.
+interface ExtendedRenderOptions extends Omit<RenderOptions, "queries"> {
+  preloadedState?: PreloadedState<RootState>;
+  store?: AppStore;
+}
+
+export function renderWithProviders(
+  ui: React.ReactElement,
+  {
+    preloadedState = {},
+    // Automatically create a store instance if no store was passed in
+    store = setupStore(preloadedState),
+    ...renderOptions
+  }: ExtendedRenderOptions = {}
+) {
+  function Wrapper({ children }: PropsWithChildren<{}>): JSX.Element {
+    return <Provider store={store}>{children}</Provider>;
+  }
+  return { store, ...render(ui, { wrapper: Wrapper, ...renderOptions }) };
+}