add set property action in background

test/background/reducers/setting.test.js

@@ -16,4 +16,22 @@ describe("setting reducer", () => {
     let state = settingReducer(undefined, action);
     expect(state).to.have.deep.property('value', { key: 123 });
   });
+
+  it('return next state for SETTING_SET_PROPERTY', () => {
+    let state = {
+      value: {
+        properties: { smoothscroll: true }
+      }
+    }
+    let action = {
+      type: actions.SETTING_SET_PROPERTY,
+      name: 'encoding',
+      value: 'utf-8',
+    };
+    state = settingReducer(state, action);
+
+    console.log(state);
+    expect(state.value.properties).to.have.property('smoothscroll', true);
+    expect(state.value.properties).to.have.property('encoding', 'utf-8');
+  });
 });