ppx_expect

Tech stack & purpose

Ppx_expect is a testing framework for OCaml that works similarly to Cram, built on top of the inline test framework. It provides a `let%expect_test` construct that allows developers to write tests containing output-generating code interleaved with `[%expect]` blocks that specify expected output. The framework automatically captures program output, compares it against expectations, and generates ".corrected" files with diffs when tests fail, making it easy to update tests with actual output. The project is written in OCaml and is maintained by Jane Street, as evidenced by references to Jane Street's inline test framework and related helper libraries. Ppx_expect handles sophisticated test scenarios including exception handling, unreachable code paths, multiple test executions with different outputs, and formatting-aware output matching that normalizes whitespace while preserving relative indentation and structure.

Community & reference links

• Cram
• `Expect_test_helpers_core`
• ppx\_inline\_test
• ppx_inline_test

Languages

Contributors

• 
  Xavier Clerc48 commits · 116 followers
• 
  jdimino-js42 commits · 0 followers
• 
  public-release33 commits · 11 followers
• 
  Thomas Refis28 commits · 166 followers
• 
  Arseniy Alekseyev20 commits · 61 followers
• 
  dkalinichenko-js2 commits · 9 followers
• 
  Eduardo Rafael1 commits · 1,103 followers
• 
  Kate1 commits · 375 followers
• 
  Jakub Staroń1 commits · 16 followers
• Jonah Beckford1 commits
• 
  Reynir Björnsson1 commits · 158 followers
• Nymphium1 commits
• Bryan Phelps1 commits