Add spec for timeRange reducer

ui/spec/data_explorer/reducers/timeRangeSpec.js

@@ -0,0 +1,31 @@
+import reducer from 'src/data_explorer/reducers/timeRange';
+
+import {
+  setTimeRange,
+} from 'src/data_explorer/actions/view';
+
+const noopAction = () => {
+  return {type: 'NOOP'};
+}
+
+describe('DataExplorer.Reducers.TimeRange', () => {
+  it('it sets the default timeRange', () => {
+    const state = reducer(undefined, noopAction());
+    const expected = {
+      lower: 'now() - 15m',
+      upper: null,
+    };
+
+    expect(state).to.deep.equal(expected);
+  });
+
+  it('it can set the time range', () => {
+    const timeRange = {
+      lower: 'now() - 5m',
+      upper: null,
+    };
+    const expected = reducer(undefined, setTimeRange(timeRange));
+
+    expect(timeRange).to.deep.equal(expected);
+  });
+});

ui/src/data_explorer/reducers/timeRange.js

@@ -1,6 +1,11 @@
 import update from 'react-addons-update';
 
-export default function timeRange(state = {}, action) {
+const initialState = {
+  upper: null,
+  lower: 'now() - 15m',
+};
+
+export default function timeRange(state = initialState, action) {
   switch (action.type) {
     case 'SET_TIME_RANGE': {
       const {upper, lower} = action.payload;