package testo-diff

  1. Overview
  2. Docs
Pure-OCaml diff implementation

Install

dune-project
 Dependency

Authors

Maintainers

Sources

testo-0.2.0.tbz
sha256=0998766656d9a756f87c2f6c78b803d3a6e7c1230167c039f288226428cc3137
sha512=bc59a43617d005bc338950b13a2aadb2865bc92ec0d1494e2219d8446e9203916c0c88878dc918ef3b8d2923b874c24bd68cf3a14a8307a0714d6114549f36ef

Description

This is a pure-OCaml implementation for computing line-by-line diffs. The current implementation uses an algorithm similar to gestalt pattern matching ported to OCaml by Gabriel Jaldon from Paul Butler's Python implementation. See https://github.com/paulgb/simplediff

Published: 12 Sep 2025

README

Testo CircleCI badge

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Documentation

Features

Testo is a test framework for OCaml that takes inspiration from its predecessor Alcotest and from pytest. Features include:

  • support for explicit XFAIL tests i.e. tests that are expected to fail, indicating that they should be fixed eventually;
  • support for test snapshots i.e. persistent storage of captured stdout or stderr;
  • reviewing and approving tests without re-running them;
  • nested test suites;
  • various ways to select tests;
  • parallel execution (using multiprocessing);
  • supports OCaml >= 4.08.

Like with Alcotest, a test executable is generated from a list of tests written in OCaml. The function to interpret the command line and run things is Testo.interpret_argv. The core subcommands supported by a test executable are:

  • run: run tests
  • status: check the status of the tests without re-running them
  • approve: approve test output and make it the new reference

A test is fundamentally a name and test function of type unit -> unit. A test is considered successful if the test function returns normally and is considered failed if it raises an exception. A test is created with Testo.create which takes a variety of options in addition to the name and the test function.

Testo doesn't provide a library for writing assertions. Using the Alcotest module for this is recommended. For example, checking that some test result res equals an expected value of 42 is written as:

Alcotest.(check int) "equal" 42 res;

This raises an exception that is turned into a nice error message.

Dependencies (3)

  1. ppx_deriving
  2. ocaml >= "4.08.0"
  3. dune >= "3.7"

Dev Dependencies (1)

  1. odoc with-doc

Used by (1)

  1. testo-util >= "0.2.0"

Conflicts

None