Testo

Party hard, test harder — DJ Testo

🚧 This project hasn't been released on Opam yet, and is still subject to frequent interface changes.

• Getting started
• Howtos
• API reference

Overview

Testo is a test framework for OCaml that takes inspiration from its predecessor Alcotest and from pytest. Testo adds the following features to Alcotest:

• comparing test outcome with expectation, allowing tests to be expected to fail;
• comparing captured output with expected output;
• approving new output;
• reviewing test status without re-running them;
• nested test suites;
• tags;
• more ways to select tests.

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
• status
• approve

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.