From a673a5f11eb3e881f85bdc346ac991b128cbcb51 Mon Sep 17 00:00:00 2001
From: Ulf Gebhardt <ulf.gebhardt@webcraft-media.de>
Date: Sun, 3 Oct 2021 13:41:20 +0200
Subject: [PATCH] missing change

---
 backend/src/util/decay.test.ts | 24 +++++++++++++++++++++++-
 backend/src/util/decay.ts      |  8 ++++----
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/backend/src/util/decay.test.ts b/backend/src/util/decay.test.ts
index 645cdf6f0..1dbd37595 100644
--- a/backend/src/util/decay.test.ts
+++ b/backend/src/util/decay.test.ts
@@ -1,6 +1,28 @@
-import { calculateDecay } from './decay'
+import { decayFormula, calculateDecay } from './decay'
 
 describe('utils/decay', () => {
+  describe('decayFormula', () => {
+    it('has base 0.99999997802044727', async () => {
+      const amount = 1.0
+      const seconds = 1
+      expect(await decayFormula(amount, seconds)).toBe(0.99999997802044727)
+    })
+    it.skip('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 () => {
+      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
+      const seconds = 1
+      expect(await decayFormula(amount, seconds)).toBe(1.0)
+    })
+  })
   it.skip('has base 0.99999997802044727', async () => {
     const now = new Date()
     now.setSeconds(1)
diff --git a/backend/src/util/decay.ts b/backend/src/util/decay.ts
index 7b064b0b1..7ea97ada9 100644
--- a/backend/src/util/decay.ts
+++ b/backend/src/util/decay.ts
@@ -1,9 +1,9 @@
 import { getCustomRepository } from 'typeorm'
-import { Decay } from '../graphql/models/Decay'
+import { Decay } from '../graphql/model/Decay'
 import { TransactionRepository } from '../typeorm/repository/Transaction'
 
-function decayFormula(amount: number, durationInSeconds: number): number {
-  return amount * Math.pow(0.99999997802044727, durationInSeconds)
+function decayFormula(amount: number, seconds: number): number {
+  return amount * Math.pow(0.99999997802044727, seconds) // This number represents 50% decay a year
 }
 
 async function calculateDecay(amount: number, from: Date, to: Date): Promise<number> {
@@ -56,4 +56,4 @@ async function calculateDecayWithInterval(
   return result
 }
 
-export { calculateDecay, calculateDecayWithInterval }
+export { decayFormula, calculateDecay, calculateDecayWithInterval }