report_guide.md

How to Report Bugs and Propose Features

Thank you for your interest in improving TypeProf! When reporting a bug or proposing a feature, including a scenario file is very helpful (but not mandatory).

What is a Scenario File?

A scenario file describes TypeProf's behavior — the input code and the expected type inference result. You can find many examples in the scenario/ directory.

Writing a Scenario File

Basic pattern

A minimal scenario file has two sections: ## update (input code) and ## assert (expected type signatures in RBS syntax).

## update
def foo(n)
  n.to_s
end

foo(42)

## assert
class Object
  def foo: (Integer) -> String
end

Multiple updates

You can include multiple ## update / ## assert pairs to test how TypeProf handles code changes:

## update
def foo = "symbol#{ 42 }"

## assert
class Object
  def foo: -> String
end

## update
def foo = :"symbol#{ 42 }"

## assert
class Object
  def foo: -> Symbol
end

Diagnostics

Use ## diagnostics to verify that TypeProf reports type errors at the expected locations:

## update
def foo(x)
  x
end

foo(1, 2)

## diagnostics
(5,0)-(5,3): wrong number of arguments (2 for 1)

Running a Scenario File

Run a single scenario file:

$ ruby tool/scenario_runner.rb path/to/your_scenario.rb

Run all tests:

$ bundle exec rake test

Reporting a Bug

1. Create a scenario file that reproduces the issue.
2. Run it with ruby tool/scenario_runner.rb your_scenario.rb to confirm the problem.
3. Open an issue and include:
   • Your TypeProf version (typeprof --version)
   • The scenario file content
   • What you expected vs. what actually happened