Add default number value for formatting numbers and fix all failed tests

Author: lulunac27a

src/components/CostDisplay/CostDisplay.test.js

@@ -7,8 +7,8 @@ describe('<CostDisplay />', () => {
   test('it should mount', () => {
     render(<CostDisplay />);
 
-    const CostDisplay = screen.getByTestId('CostDisplay');
+    const costDisplay = screen.getByTestId('CostDisplay');
 
-    expect(CostDisplay).toBeInTheDocument();
+    expect(costDisplay).toBeInTheDocument();
   });
 });

src/components/NumericDisplay/NumericDisplay.js

@@ -2,7 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import styles from './NumericDisplay.module.css';
 
-function formatNumber(number, shortForm = true) {
+function formatNumber(number = 0, shortForm = true) {
   //format number to short form with numeric prefixes
   if (shortForm) {
     //if short form is true

src/components/NumericDisplay/NumericDisplay.test.js

@@ -7,8 +7,8 @@ describe('<NumericDisplay />', () => {
   test('it should mount', () => {
     render(<NumericDisplay />);
 
-    const NumericDisplay = screen.getByTestId('NumericDisplay');
+    const numericDisplay = screen.getByTestId('NumericDisplay');
 
-    expect(NumericDisplay).toBeInTheDocument();
+    expect(numericDisplay).toBeInTheDocument();
   });
-});
+});