Introduce first unit test made possible because of recently demonstrated changes

Key changes were:
- Introduction of dependencies as interfaces to permit stubbing in general (Dependency Inversion Principle)
- Introduction of segregated interfaces to only require stubbing of minimal stuff (Interface Segregation Principle)

Signed-off-by: Janne Savolainen <janne.savolainen@houston-inc.com>

src/renderer/components/kube-object-menu/__snapshots__/kube-object-menu.test.tsx.snap

@@ -0,0 +1,18 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`kube-object-menu given no kube object, renders 1`] = `
+<div>
+  <i
+    class="Icon material interactive focusable"
+    id="menu_actions_1"
+    tabindex="0"
+  >
+    <span
+      class="icon"
+      data-icon-name="more_vert"
+    >
+      more_vert
+    </span>
+  </i>
+</div>
+`;

src/renderer/components/kube-object-menu/kube-object-menu.test.tsx

@@ -0,0 +1,77 @@
+/**
+ * Copyright (c) 2021 OpenLens Authors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+import React from "react";
+import { render } from "@testing-library/react";
+import "@testing-library/jest-dom/extend-expect";
+import { KubeObjectMenu } from "./kube-object-menu";
+import type { KubeObject } from "../../../common/k8s-api/kube-object";
+import type { KubeApi } from "../../../common/k8s-api/kube-api";
+import type { IHasGettableItemsForKind } from "../../../extensions/registries";
+import type { IGettableStore } from "../../../common/k8s-api/api-manager";
+import type { KubeObjectStore } from "../../../common/k8s-api/kube-object.store";
+import type { IHasName } from "../../../main/cluster";
+
+describe("kube-object-menu", () => {
+  let hideDetailsStub: () => void;
+  let editResourceTabStub: () => void;
+  let apiManagerStub: IGettableStore;
+  let clusterStub : IHasName;
+  let kubeObjectMenuRegistryStub: IHasGettableItemsForKind;
+  let objectStub: any;  
+
+  beforeEach(() => {
+    // TODO: Remove illegal global overwrites for what should be a dependency somewhere.
+    window.requestIdleCallback = () => 42;
+
+    window.cancelIdleCallback = () => {};
+
+    apiManagerStub = {
+      // eslint-disable-next-line unused-imports/no-unused-vars-ts
+      getStore: <TKubeObjectStore extends KubeObjectStore<KubeObject>>(api: string | KubeApi<KubeObject>): TKubeObjectStore | undefined => undefined,
+    };
+
+    clusterStub = { name: "Some cluster name" };
+
+    kubeObjectMenuRegistryStub = {
+      // eslint-disable-next-line unused-imports/no-unused-vars-ts
+      getItemsForKind: (kind: string, apiVersion: string): any => undefined,
+    };
+
+    hideDetailsStub = () => {};
+
+    editResourceTabStub = () => {};
+  });
+
+  it("given no kube object, renders", () => {
+    objectStub = null;
+
+    const { container } = render(<KubeObjectMenu object={objectStub}
+      apiManager={apiManagerStub}
+      cluster={clusterStub}
+      kubeObjectMenuRegistry={kubeObjectMenuRegistryStub}
+      hideDetails={hideDetailsStub}
+      editResourceTab={editResourceTabStub}
+    />);
+
+    expect(container).toMatchSnapshot();
+  });
+});