Merge branch 'development' into fix/docLinks

* development:
  Update and standardize contracts README
  Add to CHANGELOG
  Refactor toBaseUnitAmount so that it throws if user supplies unitAmount with too many decimals
  Make assertion stricter so that one cannot submit invalid baseUnit amounts to `toUnitAmount`
  Add some missed underscores, update changelog and comments
  Add new underscore-privates rule to @0xproject/tslint-config and fix lint errors

# Conflicts:
#	packages/website/ts/pages/documentation/documentation.tsx
#	packages/website/ts/pages/shared/nested_sidebar_menu.tsx

1 files changed, 5 insertions, 1 deletions

diff --git a/packages/0x.js/src/0x.ts b/packages/0x.js/src/0x.ts
index 7393cc814..a18f1fc55 100644
--- a/packages/0x.js/src/0x.ts
+++ b/packages/0x.js/src/0x.ts
@@ -128,7 +128,7 @@ export class ZeroEx {
      * @return  The amount in units.
      */
     public static toUnitAmount(amount: BigNumber, decimals: number): BigNumber {
-        assert.isBigNumber('amount', amount);
+        assert.isValidBaseUnitAmount('amount', amount);
         assert.isNumber('decimals', decimals);
 
         const aUnit = new BigNumber(10).pow(decimals);
@@ -149,6 +149,10 @@ export class ZeroEx {
 
         const unit = new BigNumber(10).pow(decimals);
         const baseUnitAmount = amount.times(unit);
+        const hasDecimals = baseUnitAmount.decimalPlaces() !== 0;
+        if (hasDecimals) {
+            throw new Error(`Invalid unit amount: ${amount.toString()} - Too many decimal places`);
+        }
         return baseUnitAmount;
     }
     /**