Add specs to emails context, clean up another dialyzer error

lib/code_corps/emails/emails.ex

@@ -1,54 +1,75 @@
 defmodule CodeCorps.Emails do
-  alias CodeCorps.Emails.{API, Tasks, Transmissions}
+  alias CodeCorps.{
+    Conversation,
+    ConversationPart,
+    Emails.API,
+    Emails.Tasks,
+    Emails.Transmissions,
+    Message,
+    OrganizationInvite,
+    Project,
+    ProjectUser,
+    StripeConnectCharge,
+    User
+  }
 
   defdelegate create_templates, to: Tasks
   defdelegate update_templates, to: Tasks
 
+  @spec send_forgot_password_email(User.t, String.t) :: API.transmission_result
   def send_forgot_password_email(user, token) do
     user |> Transmissions.ForgotPassword.build(token) |> API.send_transmission
   end
 
-  def send_message_initiated_by_project_email(message, conversation) do
+  @spec send_message_initiated_by_project_email(Message.t, Conversation.t) :: API.transmission_result
+  def send_message_initiated_by_project_email(%Message{} = message, %Conversation{} = conversation) do
     message
     |> Transmissions.MessageInitiatedByProject.build(conversation)
     |> API.send_transmission
   end
 
-  def send_organization_invite_email(invite) do
+  @spec send_organization_invite_email(OrganizationInvite.t) :: API.transmission_result
+  def send_organization_invite_email(%OrganizationInvite{} = invite) do
     invite |> Transmissions.OrganizationInvite.build |> API.send_transmission
   end
 
-  def send_project_approval_request_email(project) do
+  @spec send_project_approval_request_email(Project.t) :: API.transmission_result
+  def send_project_approval_request_email(%Project{} = project) do
     project
     |> Transmissions.ProjectApprovalRequest.build
     |> API.send_transmission
   end
 
-  def send_project_approved_email(project) do
+  @spec send_project_approved_email(Project.t) :: API.transmission_result
+  def send_project_approved_email(%Project{} = project) do
     project |> Transmissions.ProjectApproved.build |> API.send_transmission
   end
 
-  def send_project_user_acceptance_email(project_user) do
+  @spec send_project_user_acceptance_email(ProjectUser.t) :: API.transmission_result
+  def send_project_user_acceptance_email(%ProjectUser{} = project_user) do
     project_user
     |> Transmissions.ProjectUserAcceptance.build
     |> API.send_transmission
   end
 
-  def send_project_user_request_email(project_user) do
+  @spec send_project_user_request_email(ProjectUser.t) :: API.transmission_result
+  def send_project_user_request_email(%ProjectUser{} = project_user) do
     project_user
     |> Transmissions.ProjectUserRequest.build
     |> API.send_transmission
   end
 
-  def send_receipt_email(charge, invoice) do
+  @spec send_receipt_email(StripeConnectCharge.t, Stripe.Invoice.t) :: API.transmission_result
+  def send_receipt_email(%StripeConnectCharge{} = charge, %Stripe.Invoice{} = invoice) do
     case charge |> Transmissions.Receipt.build(invoice) do
       %SparkPost.Transmission{} = transmission ->
         transmission |> API.send_transmission
       {:error, reason} -> {:error, reason}
     end
   end
 
-  def send_reply_to_conversation_email(part, user) do
+  @spec send_reply_to_conversation_email(ConversationPart.t, User.t) :: API.transmission_result
+  def send_reply_to_conversation_email(%ConversationPart{} = part, %User{} = user) do
     part
     |> Transmissions.ReplyToConversation.build(user)
     |> API.send_transmission

lib/code_corps/messages/messages.ex

@@ -47,7 +47,7 @@ defmodule CodeCorps.Messages do
   @doc ~S"""
   Gets a `CodeCorps.Conversation` record
   """
-  @spec get_conversation(integer) :: Conversation.t
+  @spec get_conversation(integer) :: Conversation.t | nil
   def get_conversation(id) do
     Conversation |> Repo.get(id)
   end
@@ -59,7 +59,7 @@ defmodule CodeCorps.Messages do
   @doc ~S"""
   Gets a `CodeCorps.ConversationPart` record
   """
-  @spec get_part(integer) :: Conversation.t
+  @spec get_part(integer) :: ConversationPart.t | nil
   def get_part(id) do
     ConversationPart |> Repo.get(id)
   end