Add the LiveCase template for testing LiveViews.

test/support/live_case.ex

@@ -0,0 +1,75 @@
+defmodule DecentralisedBookIndexWeb.LiveCase do
+  @moduledoc """
+  This module defines the setup for tests requiring
+  access to the application's data layer.
+
+  You may define functions here to be used as helpers in
+  your tests.
+
+  Finally, if the test case interacts with the database,
+  we enable the SQL sandbox, so changes done to the database
+  are reverted at the end of every test. If you are using
+  PostgreSQL, you can even run database tests asynchronously
+  by setting `use DecentralisedBookIndex.DataCase, async: true`, although
+  this option is not recommended for other databases.
+  """
+
+  use ExUnit.CaseTemplate
+
+  using do
+    quote do
+      alias DecentralisedBookIndex.Repo
+
+      import Ecto
+      import Ecto.Changeset
+      import Ecto.Query
+      import DecentralisedBookIndex.DataCase
+      import DecentralisedBookIndex.Generators
+      import DecentralisedBookIndex.Helpers
+
+      # The default endpoint for testing
+      @endpoint DecentralisedBookIndexWeb.Endpoint
+
+      use DecentralisedBookIndexWeb, :verified_routes
+
+      # Import conveniences for testing with connections
+      import Plug.Conn
+      import Phoenix.ConnTest
+      import DecentralisedBookIndexWeb.ConnCase
+      import Phoenix.LiveViewTest
+    end
+  end
+
+  setup tags do
+    DecentralisedBookIndex.DataCase.setup_sandbox(tags)
+    {:ok, conn: Phoenix.ConnTest.build_conn()}
+  end
+
+  @doc """
+  Sets up the sandbox based on the test tags.
+  """
+  def setup_sandbox(tags) do
+    pid =
+      Ecto.Adapters.SQL.Sandbox.start_owner!(DecentralisedBookIndex.Repo,
+        shared: not tags[:async]
+      )
+
+    on_exit(fn -> Ecto.Adapters.SQL.Sandbox.stop_owner(pid) end)
+  end
+
+  @doc """
+  A helper that transforms changeset errors into a map of messages.
+
+      assert {:error, changeset} = Accounts.create_user(%{password: "short"})
+      assert "password is too short" in errors_on(changeset).password
+      assert %{password: ["password is too short"]} = errors_on(changeset)
+
+  """
+  def errors_on(changeset) do
+    Ecto.Changeset.traverse_errors(changeset, fn {message, opts} ->
+      Regex.replace(~r"%{(\w+)}", message, fn _, key ->
+        opts |> Keyword.get(String.to_existing_atom(key), key) |> to_string()
+      end)
+    end)
+  end
+end