add getSystemSurplus function

makerdao · May 22, 2020 · 0436bbe · jparklev · Jun 5, 2020 · tyler17
1 parent 378bac3
commit 0436bbe
Show file tree

Hide file tree

Showing 2 changed files with 17 additions and 0 deletions.
diff --git a/packages/dai-plugin-mcd/src/SystemDataService.js b/packages/dai-plugin-mcd/src/SystemDataService.js
@@ -1,6 +1,7 @@
 import { PublicService } from '@makerdao/services-core';
 import { RAD, RAY, ServiceRoles, SECONDS_PER_YEAR } from './constants';
 import BigNumber from 'bignumber.js';
+import { MDAI } from './index';
 
 export default class SystemDataService extends PublicService {
   constructor(name = ServiceRoles.SYSTEM_DATA) {
@@ -33,6 +34,15 @@ export default class SystemDataService extends PublicService {
     return live.eq(0);
   }
 
+  async getSystemSurplus() {
+    const vowAddr = this.get('smartContract').getContractAddress('MCD_VOW');
+    const [ dai, sin ] = await Promise.all([
+      this.vat.dai(vowAddr),
+      this.vat.sin(vowAddr)
+    ]);
+    return MDAI.rad(dai).minus(MDAI.rad(sin));
+  }
+
   // Helpers ----------------------------------------------
 
   get cat() {

diff --git a/packages/dai-plugin-mcd/test/SystemDataService.spec.js b/packages/dai-plugin-mcd/test/SystemDataService.spec.js
@@ -1,5 +1,6 @@
 import { mcdMaker } from './helpers';
 import { ServiceRoles } from '../src/constants';
+import { MDAI } from '../src/index';
 
 let service;
 let maker;
@@ -23,3 +24,9 @@ test('get global settlement status', async () => {
   const cage = await service.isGlobalSettlementInvoked();
   expect(cage).toBe(false);
 });
+
+test('get system surplus', async () => {
+  const surplus = await service.getSystemSurplus();
+  console.log('surplus.toNumber', surplus.toNumber());
+  expect(surplus).toEqual(MDAI(0)); //TODO change to expect non-zero number
+});