fix test and more checks

backend/src/util/decay.test.ts

@@ -2,24 +2,25 @@ import { decayFormula, calculateDecay } from './decay'
 
 describe('utils/decay', () => {
   describe('decayFormula', () => {
-    it('has base 0.99999997802044727', async () => {
+    it('has base 0.99999997802044727', () => {
       const amount = 1.0
       const seconds = 1
-      expect(await decayFormula(amount, seconds)).toBe(0.99999997802044727)
+      expect(decayFormula(amount, seconds)).toBe(0.99999997802044727)
     })
     // Not sure if the following skiped tests make sence!?
-    it.skip('has negative decay?', async () => {
+    it('has negative decay?', async () => {
       const amount = -1.0
       const seconds = 1
       expect(await decayFormula(amount, seconds)).toBe(-0.99999997802044727)
     })
-    it.skip('has correct backward calculation', async () => {
+    it('has correct backward calculation', async () => {
       const amount = 1.0
       const seconds = -1
       expect(await decayFormula(amount, seconds)).toBe(1.0000000219795533)
     })
-    it.skip('has correct forward calculation', async () => {
-      const amount = 1.000000219795533
+    // not possible, nodejs hasn't enough accuracy
+    it('has correct forward calculation', async () => {
+      const amount = 1.0 / 0.99999997802044727
       const seconds = 1
       expect(await decayFormula(amount, seconds)).toBe(1.0)
     })
@@ -32,7 +33,7 @@ describe('utils/decay', () => {
     expect(await calculateDecay(1.0, oneSecondAgo, now)).toBe(0.99999997802044727)
   })
 
-  it.skip('returns input amount when from and to is the same', async () => {
+  it('returns input amount when from and to is the same', async () => {
     const now = new Date()
     expect(await calculateDecay(100.0, now, now)).toBe(100.0)
   })

backend/src/util/decay.ts

@@ -10,6 +10,12 @@ async function calculateDecay(amount: number, from: Date, to: Date): Promise<num
   if (amount === undefined || !from || !to) {
     throw new Error('at least one parameter is undefined')
   }
+  if(from === to) { 
+    return amount
+  }
+  if(to < from) {
+    throw new Error('to < from, so the target date is in the past?')
+  }
   // load decay start block
   const transactionRepository = getCustomRepository(TransactionRepository)
   const decayStartBlock = await transactionRepository.findDecayStartBlock()