feat: autogenerate schema associations with factories

[cylkdev]

I'm proposing an implementation in this pr for auto generating an Ecto.Schema's association fields for factories. The factories are great for a source of truth however with complex relations the amount of calls made to create one increases. The goal is reduce the amount of code required to setup relations while being simple enough to define in one function call.

The use the association building feature you need to specify the app to load the factory modules. There are two options for configuring the behavior:

app: OTP app name
prefix: The factory modules prefix.

for eg. MyApp.Support.Factory.Accounts.User has the app name my_app and the prefix Factory for the module name.

To use the factory generation for associations you must set the relational option to a list of association fields as atoms or :all and the validate option must be true. Associations are derived from an Ecto.Schema's Reflection and is handled by the FactoryEx.Utils.Ecto.Schema.Reflection module. Ecto.Changeset.cast_assoc/3 is used when validating to cast the associated fields generated in the changeset.params.

A map is created for Ecto one associations from the specified params. If the schema also exists in the schema factory and the relational key is set, the factory's build function is called and the specified params are merged on top of the result.

  iex> FactoryEx.build_params(FactoryEx.Support.Examples.Accounts.User, %{}, relational: [:role])
  %{
    birthday: ~D[2022-08-30],
    email: "[email protected]",
    gender: "female",
    location: "TN",
    name: "Aniya",
    role: %{code: "ROLE"}
  }

There are two conveniences when building the paramters for ecto many associations.

1. Factory support when building associations parameters for a changeset/2 function
   using the default syntax. This allows you to apply many changes to many paramters.

  iex> FactoryEx.build_params(FactoryEx.Support.Examples.Accounts.User, %{labels: [%{}, %{label: "overwrite_second_label"}]}, relational: [:labels])
  %{
    birthday: ~D[2022-08-30],
    email: "[email protected]",
    gender: "female",
    labels: [%{label: "ut"}, %{label: "overwrite_second_label"}],
    location: "FL",
    name: "Rollin"
  }

2. Tuple syntax of {count, params} for applying one set of changes to many paramters. This syntax only is expanded when the relational option is set for the key.

  iex> FactoryEx.build_params(FactoryEx.Support.Examples.Accounts.User, %{labels: {2, %{label: "same_label"}}}, relational: [:labels])
  %{
    birthday: ~D[2022-08-30],
    email: "[email protected]",
    gender: "female",
    labels: [%{label: "same_label"}, %{label: "same_label"}],
    location: "TN",
    name: "Berniece"
  }

The parameters are created before being converted to a struct or changeset.

Changelog

• Added FactoryEx.AssociationBuilder and FactoryEx.FactoryStore for generating parameters
  for Ecto Associations with Factory.
• FactoryEx.SchemaCounter.start is now automatically when the factory_ex application starts.
• validate when false deep converts params to ecto schema structs.
• Moved previous schemas from test/support to test/support/schema
• Created factories for schemas under test/support/factory
• Created ecto migrations
• Added ecto repo config for testing

[MikaAK]

Just a note I'm currently working with @cylkdev to refactor this a bit before review