Merge branch 'sol-cov-fixes' of github.com:0xProject/0x-monorepo into sol-cov-fixes

* 'sol-cov-fixes' of github.com:0xProject/0x-monorepo: (49 commits)
  Add @return comments
  Import marshaller directly
  Update comment about ethers checksummed address behavior
  Add packages/coverage/.gitkeep file
  Update CI config and package.json to run @0xproject/utils tests on CI
  Update remaining CHANGELOG.json files
  Change amir picture
  Update CHANGELOG.json for contract-wrappers
  Update ethers typings for TypeScript 2.9.2
  Update CHANGELOG.json for base-contract
  Move some ethers-related types to typescript-typings/ethers
  Apply prettier
  Add strictArgumentEncodingCheck to BaseContract and use it in contract templates
  fix(monorepo-scripts): Fix typo in git tag command
  feat(monorepo-scripts): Add confirmation prompt before publishing
  fix comments and styling for MixinSignatureValidator
  Update TypeScript to version 2.9.2
  Use asm for hashEIP712Message, increment free memory pointer after asm hashing functions
  Fix comments, styling, and optimize hashOrder
  Remove assertion comments
  ...

1 files changed, 2 insertions, 0 deletions

diff --git a/packages/contract-wrappers/src/utils/constants.ts b/packages/contract-wrappers/src/utils/constants.ts
index 039475b7f..2df11538c 100644
--- a/packages/contract-wrappers/src/utils/constants.ts
+++ b/packages/contract-wrappers/src/utils/constants.ts
@@ -2,6 +2,7 @@ import { BigNumber } from '@0xproject/utils';
 
 export const constants = {
     NULL_ADDRESS: '0x0000000000000000000000000000000000000000',
+    NULL_BYTES: '0x',
     TESTRPC_NETWORK_ID: 50,
     INVALID_JUMP_PATTERN: 'invalid JUMP at',
     REVERT: 'revert',
@@ -10,4 +11,5 @@ export const constants = {
     // tslint:disable-next-line:custom-no-magic-numbers
     UNLIMITED_ALLOWANCE_IN_BASE_UNITS: new BigNumber(2).pow(256).minus(1),
     DEFAULT_BLOCK_POLLING_INTERVAL: 1000,
+    ZERO_AMOUNT: new BigNumber(0),
 };