fix: Test case failure in discharge state

Signed-off-by: Ntoutes <zhaoruiyuan2@huawei.com>

powermgr/battery_manager/src/main/js/default/test/battery_unit.test.js

@@ -288,7 +288,7 @@ describe('appInfoTest', function () {
     it('nowCurrent_test', 0, function () {
         let nowCurrent = batteryInfo.nowCurrent;
         console.info('nowCurrent = ' + nowCurrent);
-        expect(nowCurrent >= 0).assertTrue();
+        expect(nowCurrent >= -20000 && nowCurrent <= 20000).assertTrue();
     })
 
     /**