Rewrites Mix.install dependency declarations for local testing.

This is the core feature of LivebookTest and the third stage in the pipeline:

Discovery → Exporter → **DependencyPatcher** → Runner → Report

Why dependency patching matters

Livebook notebooks are standalone documents. They declare their dependencies using Mix.install/2 with Hex version specifiers:

Mix.install([
  {:my_lib, "~> 0.5"}
])

When testing notebooks as part of a project's CI pipeline, you want those notebooks to use the current checkout of my_lib, not the published Hex version. This module rewrites the dependency declarations to use local paths instead.

Modes

• Remote (:remote) — leave the script untouched
• Local (:local) — rewrite Hex deps to local path deps

How patching works

The patcher operates on the exported Elixir script (not the .livemd), using regex-based replacement to rewrite Mix.install calls:

# Before (remote)
Mix.install([{:my_lib, "~> 0.5"}])

# After (local)
Mix.install([{:my_lib, path: "."}])