add tests

test/background/actions/tab.test.js

@@ -0,0 +1,13 @@
+import actions from 'background/actions';
+import * as tabActions from 'background/actions/tab';
+
+describe("tab actions", () => {
+  describe("selected", () => {
+    it('create TAB_SELECTED action', () => {
+      let action = tabActions.selected(123);
+      expect(action.type).to.equal(actions.TAB_SELECTED);
+      expect(action.tabId).to.equal(123);
+    });
+  });
+});
+

test/background/reducers/tab.test.js

@@ -0,0 +1,22 @@
+import actions from 'background/actions';
+import tabReducer from 'background/reducers/tab';
+
+describe("tab reducer", () => {
+  it('return the initial state', () => {
+    let state = tabReducer(undefined, {});
+    expect(state.previousSelected).to.equal(-1);
+    expect(state.currentSelected).to.equal(-1);
+  });
+
+  it('return next state for TAB_SELECTED', () => {
+    let state = undefined;
+
+    state = tabReducer(state, { type: actions.TAB_SELECTED, tabId: 123 });
+    expect(state.previousSelected).to.equal(-1);
+    expect(state.currentSelected).to.equal(123);
+
+    state = tabReducer(state, { type: actions.TAB_SELECTED, tabId: 456 });
+    expect(state.previousSelected).to.equal(123);
+    expect(state.currentSelected).to.equal(456);
+  });
+});