Skuld.Effects.Port.Repo.Stub (skuld v0.24.0)

Stateless stub Repo handler for tests.

Thin wrapper around DoubleDown.Repo.Stub that provides skuld's handler API. Write operations (insert, update, delete) apply changeset changes and return {:ok, struct} but store nothing. Read operations go through an optional fallback function, or raise.

Usage

alias Skuld.Effects.Port
alias Skuld.Effects.Port.Repo

# Writes only — reads will raise:
comp
|> Port.with_fn_handler(Repo.Stub.new())
|> Comp.run!()

# With fallback for reads:
comp
|> Port.with_fn_handler(Repo.Stub.new(
  fallback_fn: fn
    :get, [User, 1] -> %User{id: 1, name: "Alice"}
    :all, [User] -> [%User{id: 1, name: "Alice"}]
  end
))
|> Comp.run!()

Differences from Repo.InMemory / Repo.OpenInMemory

Repo.Stub is stateless — writes apply changesets and return {:ok, struct} but nothing is stored. There is no read-after-write consistency. Use Repo.Stub when you only need fire-and-forget writes.

Fallback function

The fallback function receives (operation, args) — the skuld-idiomatic 2-arity convention. The wrapper adapts it to DD's 3-arity (contract, operation, args) convention internally.

Summary

Functions

new(opts \\ [])

Create a new Stub handler function.

Functions

new(opts \\ [])

@spec new(keyword()) :: (module(), atom(), [term()] -> term())

Create a new Stub handler function.

Returns a 3-arity function (contract, operation, args) -> result suitable for use with Port.with_fn_handler/2.

Options

:fallback_fn - a 2-arity function (operation, args) -> result that handles read operations.

Examples

Repo.Stub.new()
Repo.Stub.new(
  fallback_fn: fn
    :get, [User, 1] -> %User{id: 1, name: "Alice"}
    :all, [User] -> [%User{id: 1, name: "Alice"}]
  end
)