Concurrently attributes missing checker

[hiagomeels]

8

It will add a checker to verify if the following module attributes are set up to true when the migration contains an operation to add or drop an index concurrently.

@disable_ddl_transaction true
@disable_migration_lock true

As said here, the unique way that I found to include this feature was going through the entire code_ast.

• Created a new module to add full detections checkers (AstParserFullDetections)
• Add the detect_invalid_index_concurrently validation

The checker consists of post-walk with the AST and checking:

• If some of the operations are adding a concurrent index

  defp detect_invalid_index_concurrently_inner({fun_name, location, [{operation, _, [_, _, options]}]} = ast_part, acc)
   when fun_name in @index_functions and operation in @index_types do
  
  is_concurrently? = Keyword.get(options, :concurrently, false) || acc.is_index_concurrently?
  line = if is_concurrently?, do: Keyword.get(location, :line), else: acc.line
  
  {ast_part, %{acc | is_index_concurrently?: is_concurrently?, line: line}}
  end

• If the attributes exist in the module and setted as true

  
  defp detect_invalid_index_concurrently_inner( {:disable_ddl_transaction, _, [true]} = ast_part, acc) do
  {ast_part, %{acc | has_transaction?: true}}
  end

defp detect_invalid_index_concurrently_inner(disable_migrationlock, , [true]} = ast_part, acc) do {ast_part, %{acc | has_lock?: true}} end

I also created this initial accumulator map with these default params to be easier to handle with this logic:
```Elixir
%{
      line: nil,
      is_index_concurrently?: false,
      has_transaction?: false,
      has_lock?: false
}

For now, I have named these news danger types index_concurrently_without_disable_ddl_transaction and index_concurrently_without_disable_migration_lock, but I'm not sure which will be a more appropriate name for them.

Let me know your thoughts on that.

[hiagomeels]

Should each of these full file detections checker live in their own modules? I think breaking it down into multiple modules will also be more readable and testable. Any thoughts?

[Artur-Sulej]

One more thing – index_concurrently_without_disable_ddl_transaction and index_concurrently_without_disable_migration_lock should be added to README.md.

[hiagomeels]

@Artur-Sulej

One more thing – index_concurrently_without_disable_ddl_transaction and index_concurrently_without_disable_migration_lock should be added to README.md.

I have created this PR to do it.