Ethereum Object Format Tests

Ori Pomerantz

In this tutorial you learn how to write and execute EOF tests. These tests let you check various combinations to see what is accepted as valid EOF and what is rejected.

Make sure you understand State Transition Tests before you start here.


The fillers for EOF tests are in …/src/EOFFiller. This tutorial explains the YML filler, …/src/EOFFiller/efExample/ymlExampleFiller.yml.

Overall Structure

The file includes these sections:

  • _info: Human readable comments.
  • data: A list of entries. Each entry is init code that can create a contract
  • expect: The expected results.

The Data Section

Each entry in the data is typically :raw bytes, because we are checking a data format. However, because EOF is a lot more complicated than most raw data provided in tests, it is a good idea to use multi-line fields with comments. For example, this code

- |
    0xEF0001  # Magic and version
      010004  # One code segment
      020001  # One code segment
        000a  # Code segment zero length: 10 bytes
      030016  # Data segment length (the code being deployed): 0x16=22 bytes
      00      # End of header

This is functionally equivalent to

- :raw 0xEF0001010004020001000a03001600

But a lot more readable.

The Expect Section

Here is a sample expect section entry.

- indexes:
    - 0-1
  - '>=Shanghai'
  result: !!bool true

It is very similar to the expect section of a state transition test, except for these differences:

  • In the indexes subsection there is only data. These tests don’t have gas or value fields to match.
  • The result can only be one of two values:
    • !!bool true if the contract is supposed to get created
    • !!bool false if contract creation is supposed to fail