Compile-Time Hooks
Elixir allows us to set a special module attribute, @before_compile, to notify the compiler that an extra step is required just before compilation is finished. The @before_compile attribute accepts a module argument where a __before_compile__/1 macro must be defined. This macro is invoked just before compilation in order to perform a final bit of code generation. Let’s apply this hook to fix our test macro. Update your Assertion module with these @before_compile hooks:
| macros/before_compile.exs | |
| Line 1 | defmodule Assertion do |
| - | |
| - | defmacro __using__(_options) do |
| - | quote do |
| 5 | import unquote(__MODULE__) |
| - | Module.register_attribute __MODULE__, :tests, accumulate: true |
| - | @before_compile unquote(__MODULE__) ... |
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