I am probably missing something very obvious but I cannot get the simplest assert statement to work! What am I doing wrong?

My goal is to simply confirm that I am within a start date and end date range using "now".

I cannot even get assert (1==1); to return true!

Please assist!

pragma solidity ^0.4.18;

contract TestAssert {

// Unix timestamp converter used = https://www.unixtimestamp.com/
   uint256 public constant startDate = 1517907600; // 02/06/2018 09:00:00 
   uint256 public constant endDate = 1522659600; // 04/02/2018 09:00:00

//This is the Constructor
  function TestAssert() {


  function assertOneEqualsOne () returns (bool) {
    assert(1 == 1);

  function assertStartDate () constant returns(bool){
    assert(now >= startDate); 

  function assertEndDate () constant returns(bool){
    assert(now <= endDate);

  function returnNow() returns (uint256) {
    return now;

  function () payable {
     // this is the fallback function.


1 Answer 1


You need to add a return to your functions.

   function assertOneEqualsOne () external pure returns (bool) {
           assert(1 == 1);
           return true;

If the assert fails it will signal a REVERT and throw an exception in your client code.

  • Thank you VERY much! I knew it was something I was overlooking! I assumed the assert function would return it for me. Lesson learned!!!
    – wardsback
    Feb 18, 2018 at 14:25

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