test: add tests for NetworkButton component

frontend/__tests__/unit/components/NetworkButton.test.jsx

@@ -0,0 +1,39 @@
+import { render, screen } from "@testing-library/react";
+import NetworkButton from "components/HomeLoggedIn/components/NetworkButton";
+import { testNetwork } from "../../data/network";
+import { Router } from "react-router-dom";
+import { createMemoryHistory } from "history";
+
+describe("NetworkHeader", () => {
+  it("renders NetworkButton unchanged", () => {
+    const history = createMemoryHistory();
+
+    const { container } = render(
+      <Router history={history}>
+        <NetworkButton network={testNetwork} />
+      </Router>
+    );
+    expect(container).toMatchSnapshot();
+  });
+
+  test("renders NetworkHeader with a test network", () => {
+    const history = createMemoryHistory();
+
+    render(
+      <Router history={history}>
+        <NetworkButton network={testNetwork} />
+      </Router>
+    );
+
+    const networkButton = screen.getByRole("button", {
+      name: "0d303702cd0f1fc6 new-net-11166",
+    });
+
+    const networkLink = screen.getByRole("link", {
+      name: "0d303702cd0f1fc6 new-net-11166",
+    });
+
+    expect(networkButton).toBeInTheDocument();
+    expect(networkLink).toBeInTheDocument();
+  });
+});

frontend/__tests__/unit/components/__snapshots__/NetworkButton.test.jsx.snap

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+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`NetworkHeader renders NetworkButton unchanged 1`] = `
+<div>
+  <div
+    class="netBtn"
+    role="button"
+  >
+    <a
+      class="makeStyles-link-1"
+      href="/network/0d303702cd0f1fc6"
+    >
+      <ul
+        class="MuiList-root makeStyles-flexContainer-2 MuiList-padding"
+      >
+        <li
+          class="MuiListItem-root makeStyles-nwid-4 MuiListItem-gutters"
+        >
+          0d303702cd0f1fc6
+        </li>
+        <li
+          class="MuiListItem-root makeStyles-name-3 MuiListItem-gutters"
+        >
+          new-net-11166
+        </li>
+      </ul>
+    </a>
+  </div>
+</div>
+`;