add tests for licenses reducers

src/licenses/reducers.test.ts

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2021 The Pybricks Authors
+
+import { Action } from '../actions';
+import { didFetchList, select } from './actions';
+import reducers, { LicenseInfo, LicenseList } from './reducers';
+
+type State = ReturnType<typeof reducers>;
+
+test('initial state', () => {
+    expect(reducers(undefined, {} as Action)).toMatchInlineSnapshot(`
+        Object {
+          "list": null,
+          "selected": null,
+        }
+    `);
+});
+
+test('list', () => {
+    const list = [] as LicenseList;
+    expect(reducers({ list: null } as State, didFetchList(list)).list).toBe(list);
+});
+
+test('selected', () => {
+    const info = {} as LicenseInfo;
+    expect(reducers({ selected: null } as State, select(info)).selected).toBe(info);
+});