`Undefined Step` warning for step when corresponding step definition string contains an escaped forward slash

[Drew-Daniels]

👓 What did you see?

Thanks for maintaining @cucumber/language-server! It's been a breeze to use and I really enjoy using it.

This behavior could be expected (and a weird edge case if anything), but I noticed a small issue where, when a step in a .feature file contains a forward slash, the corresponding step definition glue code isn't found by the language server, even when @cucumber/cucumber can successfully locate the corresponding step definition when the tests are run.

features/config.feature

Feature: Simple test

  Scenario: GET /config
    Given I am a user
    # Notice `/config` with a forward slash prefix
    When I send a request to /config
    Then the response should contain expected config

features/config.ts

import { Given, Then, When } from '@cucumber/cucumber';

Given('I am a user', async function () {
  // no-op
});

// Notice the escaped forward slash - which is a requirement for `@cucumber/cucumber` to match this step definition to the step referenced in the feature file.
When('I send a request to \\/config{}', async function (value: string) {
  // eslint-disable-next-line no-console
  console.log(`Sending request to ${value}`);
});

Then('the response should contain expected config', async function () {
  // no-op
});

✅ What did you expect to see?

I would expect that @cucumber/language-server could locate a step definition for a feature step with a forward slash, when @cucumber/cucumber is able to match the step definition to this step and run tests as expected.

📦 Which tool/library version are you using?

❯ node -v
v24.10.0

@cucumber/cucumber: 12.1.0
@cucumber/language-server: 1.7.0

❯ uname -v
Darwin Kernel Version 25.0.0: Wed Sep 17 21:42:08 PDT 2025; root:xnu-12377.1.9~141/RELEASE_ARM64_T8132

❯ nvim --version
NVIM v0.11.4
Build type: Release
LuaJIT 2.1.1761727121

🔬 How could we reproduce it?

Clone this reproduction repository, install dependencies, run the test suite, and verify that all tests run as expected.

git clone https://github.com/Drew-Daniels/cucumber-lsp-repro
cd cucumber-lsp-repro
npm i
npm run cucumber

However, open up features/simple-maths.feature in your editor (I am using neovim) and verify that the LSP generates a warning that the step definition for the When I send a request to /config line cannot be found.

📚 Any additional context?

Here is my (abbreviated) nvim-lspconfig.lua file:

return {
	"neovim/nvim-lspconfig",
	config = function(_, _)
		local capabilities = require("blink.cmp").get_lsp_capabilities()
		-- TODO: Modularize configuration so that 'capabilities = capabilities' setting is used for every lsp
		--TODO: Deactivate eslint lsp when in an "ignored" directory so things are less noisy
		-- https://github.com/neovim/nvim-lspconfig/issues/2508
		local root_dir = vim.fs.root(0, ".git")
		local use_flat_config = false
		if root_dir ~= nil and vim.fn.filereadable(root_dir .. "/eslint.config.js") == 1 then
			use_flat_config = true
		end

		vim.lsp.config("cucumber_language_server", {
			capabilities = capabilities,
			settings = {
				cucumber = {
					glue = {
						-- Cucumber-JVM
						"src/test/**/*.java",
						-- Cucumber-Js
						"features/**/*.ts",
						"features/**/*.tsx",
						"features/**/*.js",
						"features/**/*.jsx",
						"step-definitions/**/*.ts",
						"test/features/**/*.ts",
						-- Behat
						"features/**/*.php",
						-- Behave
						"features/**/*.py",
						-- Pytest-BDD
						"tests/**/*.py",
						-- Cucumber Rust
						"tests/**/*.rs",
						"features/**/*.rs",
						-- Cucumber-Ruby
						"features/**/*.rb",
						-- SpecFlow
						"*specs*/**/*.cs",
						-- Godog
						"features/**/*_test.go",
					},
				},
			},
		})

		vim.lsp.enable({
			"cucumber_language_server",
		})
	end,
}