if (((collectionMintCost - collectionEndMintCost) / rate) > tDiff) {
    price = collectionPhases[_collectionId].collectionMintCost - (tDiff * collectionPhases[_collectionId].rate);
} else {
    price = collectionPhases[_collectionId].collectionEndMintCost;
}
if (((collectionPhases[_collectionId].collectionMintCost - collectionPhases[_collectionId].collectionEndMintCost) 
                / (collectionPhases[_collectionId].rate)) > tDiff) {
[PASS] test_changeProof() (gas: 745699)
Logs:
  4900000000000000000
  3900000000000000000
  2900000000000000000
  1000000000000000000
-  if (...) > tDiff){ 
+  if (...) >= tDiff){ 
