Fix rounding issue when sending max tokens (#5695)

* Fix rounding issue when sending max tokens

* Ensure amount row shows exact amount of max tokens on send screen (#2)

* Fix tests

* Change stored redux value from BigNumber to hex string. Fix TokenInput default value

2 files changed, 15 insertions, 6 deletions

diff --git a/ui/app/components/currency-display/currency-display.container.js b/ui/app/components/currency-display/currency-display.container.js
index 6ddf07172..e581f8a5e 100644
--- a/ui/app/components/currency-display/currency-display.container.js
+++ b/ui/app/components/currency-display/currency-display.container.js
@@ -20,15 +20,24 @@ const mergeProps = (stateProps, dispatchProps, ownProps) => {
     currency,
     denomination,
     hideLabel,
+    displayValue: propsDisplayValue,
+    suffix: propsSuffix,
     ...restOwnProps
   } = ownProps
 
   const toCurrency = currency || currentCurrency
-  const convertedValue = getValueFromWeiHex({
-    value, fromCurrency: nativeCurrency, toCurrency, conversionRate, numberOfDecimals, toDenomination: denomination,
-  })
-  const displayValue = formatCurrency(convertedValue, toCurrency)
-  const suffix = hideLabel ? undefined : toCurrency.toUpperCase()
+
+  const displayValue = propsDisplayValue || formatCurrency(
+    getValueFromWeiHex({
+      value,
+      fromCurrency: nativeCurrency,
+      toCurrency, conversionRate,
+      numberOfDecimals,
+      toDenomination: denomination,
+    }),
+    toCurrency
+  )
+  const suffix = propsSuffix || (hideLabel ? undefined : toCurrency.toUpperCase())
 
   return {
     ...restStateProps,
diff --git a/ui/app/components/currency-display/tests/currency-display.container.test.js b/ui/app/components/currency-display/tests/currency-display.container.test.js
index 0c886af50..9888c366e 100644
--- a/ui/app/components/currency-display/tests/currency-display.container.test.js
+++ b/ui/app/components/currency-display/tests/currency-display.container.test.js
@@ -131,7 +131,7 @@ describe('CurrencyDisplay container', () => {
           },
           result: {
             nativeCurrency: 'ETH',
-            displayValue: '1e-9',
+            displayValue: '0.000000001',
             suffix: undefined,
           },
         },