Add tests for settings reducer

Summary: yiss_tests

Reviewed By: jknoxville

Differential Revision: D18851134

fbshipit-source-id: 53ffb9b516773df19c258e7d819962e3cd523751

src/reducers/__tests__/settings.node.tsx

@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {default as reducer, updateSettings, Tristate} from '../settings';
+
+test('init', () => {
+  const res = reducer(undefined, {type: 'INIT'});
+  expect(res.enableAndroid).toBeTruthy();
+});
+
+test('updateSettings', () => {
+  const initialSettings = reducer(undefined, {type: 'INIT'});
+  const updatedSettings = Object.assign(initialSettings, {
+    enableAndroid: false,
+    enablePrefetching: Tristate.True,
+    jsApps: {
+      webAppLauncher: {
+        height: 900,
+      },
+    },
+  });
+  const res = reducer(initialSettings, updateSettings(updatedSettings));
+
+  expect(res.enableAndroid).toBeFalsy();
+  expect(res.enablePrefetching).toEqual(Tristate.True);
+  expect(res.jsApps.webAppLauncher.height).toEqual(900);
+  expect(res.jsApps.webAppLauncher.width).toEqual(
+    initialSettings.jsApps.webAppLauncher.width,
+  );
+});