Convert token input to BigNumber to handle decimals. (#12773)

* Fixes #12762

Adds a decimal length check for inputs and drops excess fractional part.
Another edgecase not accounted for is when a token's decimal precision is 0 and attempting sending decimals will result in omitting the fractional part.

* Change spies from sinon to jest and change onChange value to string.

* Adjust

* Remove sinon

* Add test for issue case

* DRY

* Simplify logic by using BigNumber

Co-authored-by: Dan Miller <danjm.com@gmail.com>

ui/components/ui/token-input/token-input.component.js

@@ -1,5 +1,6 @@
 import React, { PureComponent } from 'react';
 import PropTypes from 'prop-types';
+import BigNumber from 'bignumber.js';
 import UnitInput from '../unit-input';
 import CurrencyDisplay from '../currency-display';
 import { getWeiHexFromDecimalValue } from '../../../helpers/utils/conversions.util';
@@ -7,6 +8,7 @@ import {
   conversionUtil,
   multiplyCurrencies,
 } from '../../../../shared/modules/conversion.utils';
+
 import { ETH } from '../../../helpers/constants/common';
 import { addHexPrefix } from '../../../../app/scripts/lib/util';
 
@@ -81,7 +83,7 @@ export default class TokenInput extends PureComponent {
     let newDecimalValue = decimalValue;
 
     if (decimals && applyDecimals) {
-      newDecimalValue = parseFloat(decimalValue).toFixed(decimals);
+      newDecimalValue = new BigNumber(decimalValue, 10).toFixed(decimals);
     }
 
     const multiplier = Math.pow(10, Number(decimals || 0));

ui/components/ui/token-input/token-input.component.test.js

@@ -1,7 +1,6 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import { shallow, mount } from 'enzyme';
-import sinon from 'sinon';
 import { Provider } from 'react-redux';
 import configureMockStore from 'redux-mock-store';
 import UnitInput from '../unit-input';
@@ -207,12 +206,10 @@ describe('TokenInput Component', () => {
   });
 
   describe('handling actions', () => {
-    const handleChangeSpy = sinon.spy();
-    const handleBlurSpy = sinon.spy();
+    const handleChangeSpy = jest.fn();
 
     afterEach(() => {
-      handleChangeSpy.resetHistory();
-      handleBlurSpy.resetHistory();
+      handleChangeSpy.mockClear();
     });
 
     it('should call onChange on input changes with the hex value for ETH', () => {
@@ -238,8 +235,7 @@ describe('TokenInput Component', () => {
       );
 
       expect(wrapper).toHaveLength(1);
-      expect(handleChangeSpy.callCount).toStrictEqual(0);
-      expect(handleBlurSpy.callCount).toStrictEqual(0);
+      expect(handleChangeSpy.mock.calls).toHaveLength(0);
 
       const tokenInputInstance = wrapper.find(TokenInput).at(0).instance();
       expect(tokenInputInstance.state.decimalValue).toStrictEqual(0);
@@ -250,13 +246,13 @@ describe('TokenInput Component', () => {
       const input = wrapper.find('input');
       expect(input.props().value).toStrictEqual(0);
 
-      input.simulate('change', { target: { value: 1 } });
-      expect(handleChangeSpy.callCount).toStrictEqual(1);
-      expect(handleChangeSpy.calledWith('2710')).toStrictEqual(true);
+      input.simulate('change', { target: { value: '1' } });
+      expect(handleChangeSpy.mock.calls).toHaveLength(1);
+      expect(handleChangeSpy.mock.calls[0][0]).toStrictEqual('2710');
       expect(wrapper.find('.currency-display-component').text()).toStrictEqual(
         '2ETH',
       );
-      expect(tokenInputInstance.state.decimalValue).toStrictEqual(1);
+      expect(tokenInputInstance.state.decimalValue).toStrictEqual('1');
       expect(tokenInputInstance.state.hexValue).toStrictEqual('2710');
     });
 
@@ -285,8 +281,7 @@ describe('TokenInput Component', () => {
       );
 
       expect(wrapper).toHaveLength(1);
-      expect(handleChangeSpy.callCount).toStrictEqual(0);
-      expect(handleBlurSpy.callCount).toStrictEqual(0);
+      expect(handleChangeSpy.mock.calls).toHaveLength(0);
 
       const tokenInputInstance = wrapper.find(TokenInput).at(0).instance();
       expect(tokenInputInstance.state.decimalValue).toStrictEqual(0);
@@ -297,13 +292,13 @@ describe('TokenInput Component', () => {
       const input = wrapper.find('input');
       expect(input.props().value).toStrictEqual(0);
 
-      input.simulate('change', { target: { value: 1 } });
-      expect(handleChangeSpy.callCount).toStrictEqual(1);
-      expect(handleChangeSpy.calledWith('2710')).toStrictEqual(true);
+      input.simulate('change', { target: { value: '1' } });
+      expect(handleChangeSpy.mock.calls).toHaveLength(1);
+      expect(handleChangeSpy.mock.calls[0][0]).toStrictEqual('2710');
       expect(wrapper.find('.currency-display-component').text()).toStrictEqual(
         '$462.12USD',
       );
-      expect(tokenInputInstance.state.decimalValue).toStrictEqual(1);
+      expect(tokenInputInstance.state.decimalValue).toStrictEqual('1');
       expect(tokenInputInstance.state.hexValue).toStrictEqual('2710');
     });
 
@@ -345,4 +340,84 @@ describe('TokenInput Component', () => {
       );
     });
   });
+
+  describe('Token Input Decimals Check', () => {
+    const handleChangeSpy = jest.fn();
+
+    afterEach(() => {
+      handleChangeSpy.mockClear();
+    });
+
+    it('should render incorrect hex onChange when input decimals is more than token decimals', () => {
+      const mockStore = {
+        metamask: {
+          currentCurrency: 'usd',
+          conversionRate: 231.06,
+        },
+      };
+      const store = configureMockStore()(mockStore);
+      const wrapper = mount(
+        <Provider store={store}>
+          <TokenInput
+            onChange={handleChangeSpy}
+            token={{
+              address: '0x1',
+              decimals: 4,
+              symbol: 'ABC',
+            }}
+            tokenExchangeRates={{ '0x1': 2 }}
+            showFiat
+            currentCurrency="usd"
+          />
+        </Provider>,
+      );
+
+      expect(wrapper).toHaveLength(1);
+      expect(handleChangeSpy.mock.calls).toHaveLength(0);
+
+      const input = wrapper.find('input');
+      expect(input.props().value).toStrictEqual(0);
+
+      input.simulate('change', { target: { value: '1.11111' } });
+      expect(handleChangeSpy.mock.calls).toHaveLength(1);
+
+      expect(handleChangeSpy.mock.calls[0][0]).toStrictEqual(
+        '2b67.1999999999999999999a',
+      );
+    });
+
+    it('should render correct hex onChange when input decimals is more than token decimals by omitting excess fractional part on blur', () => {
+      const mockStore = {
+        metamask: {
+          currentCurrency: 'usd',
+          conversionRate: 231.06,
+        },
+      };
+      const store = configureMockStore()(mockStore);
+
+      const wrapper = mount(
+        <Provider store={store}>
+          <TokenInput
+            onChange={handleChangeSpy}
+            token={{
+              address: '0x1',
+              decimals: 4,
+              symbol: 'ABC',
+            }}
+            tokenExchangeRates={{ '0x1': 2 }}
+            showFiat
+            currentCurrency="usd"
+          />
+        </Provider>,
+      );
+      expect(wrapper).toHaveLength(1);
+
+      const input = wrapper.find('input');
+
+      input.simulate('blur', { target: { value: '1.11111' } });
+
+      expect(handleChangeSpy.mock.calls).toHaveLength(1);
+      expect(handleChangeSpy.mock.calls[0][0]).toStrictEqual('2b67');
+    });
+  });
 });