Add tests for AircraftLayer.

client/src/components/aircraftlayer/AircraftLayer.test.tsx

@@ -0,0 +1,53 @@
+import { renderWithProviders } from "../../testutils";
+import AircraftLayer from "./AircraftLayer";
+import { PropsWithChildren } from "react";
+
+const mockLayerGroup = jest.fn();
+const mockMarker = jest.fn();
+jest.mock("react-leaflet", () => ({
+  LayerGroup: (props: PropsWithChildren<any>) => {
+    mockLayerGroup(props);
+    return <>{props.children}</>;
+  },
+  Marker: (props: any) => {
+    mockMarker(props);
+  },
+}));
+
+test("layer is empty by default", async () => {
+  renderWithProviders(<AircraftLayer />);
+  expect(mockLayerGroup).toHaveBeenCalledTimes(1);
+  expect(mockMarker).not.toHaveBeenCalled();
+});
+
+test("layer has aircraft if non-empty", async () => {
+  renderWithProviders(<AircraftLayer />, {
+    preloadedState: {
+      flights: {
+        flights: {
+          foo: {
+            id: "foo",
+            blue: true,
+            sidc: "",
+            position: {
+              lat: 0,
+              lng: 0,
+            },
+          },
+          bar: {
+            id: "bar",
+            blue: false,
+            sidc: "",
+            position: {
+              lat: 0,
+              lng: 0,
+            },
+          },
+        },
+        selected: null,
+      },
+    },
+  });
+  expect(mockLayerGroup).toHaveBeenCalledTimes(1);
+  expect(mockMarker).toHaveBeenCalledTimes(2);
+});