Add coverage report

backend/jest.config.js

@@ -2,5 +2,6 @@
 module.exports = {
   verbose: true,
   preset: 'ts-jest',
-  collectCoverageFrom: ['src/**/*.ts', '!**/node_modules/**', '!**/?(*.)+test.ts'],
+  collectCoverage: true,
+  collectCoverageFrom: ['src/**/*.ts', '!**/node_modules/**'],
 }

backend/src/util/decay.test.ts

@@ -8,4 +8,9 @@ describe('utils/decay', () => {
     oneSecondAgo.setSeconds(0)
     expect(decayFunction(1.0, oneSecondAgo, now)).toBe(0.99999997802044727)
   })
+
+  it('returns input amount when from and to is the same', () => {
+    const now = new Date()
+    expect(decayFunction(100.0, now, now)).toBe(100.0)
+  })
 })