fix type errors (#14)

The child_spec was initializing the worker with a tuple instead of a
propslist.

Also, the Snowflex module was referencing two types:

  * `:odbc.odbc_data_type`
  * `:odbc.value`

These types are defined in the odbc OTP documentation, but do not
actually exist in the OTP source code.

This change corrects the child_spec call and steals the rest of the
pertinent odbc type documentation and implements it for ourselves.

Dialyzer has been installed to verify these changes, however the
child_spec change, which is part of the Connection __using__ callback,
must be (and has been) verified in a consuming library.

lib/snowflex.ex

@@ -9,11 +9,34 @@ defmodule Snowflex do
   alias Ecto.Changeset
   alias Snowflex.Worker
 
-  @type query_param :: {:odbc.odbc_data_type(), list(:odbc.value())}
+  # Shamelessly copied from http://erlang.org/doc/man/odbc.html#common-data-types-
+  @type precision :: integer()
+  @type scale :: integer()
+  @type size :: integer()
+  @type odbc_data_type ::
+          :sql_integer
+          | :sql_smallint
+          | :sql_tinyint
+          | {:sql_decimal, precision(), scale()}
+          | {:sql_numeric, precision(), scale()}
+          | {:sql_char, size()}
+          | {:sql_wchar, size()}
+          | {:sql_varchar, size()}
+          | {:sql_wvarchar, size()}
+          | {:sql_float, precision()}
+          | {:sql_wlongvarchar, size()}
+          | {:sql_float, precision()}
+          | :sql_real
+          | :sql_double
+          | :sql_bit
+          | atom()
+  @type value :: nil | term()
+
+  @type query_param :: {odbc_data_type(), [value()]}
   @type sql_data :: list(%{optional(String.t()) => String.t()})
 
   @spec sql_query(atom(), String.t(), timeout()) ::
-          sql_data() | {:error, term}
+          sql_data() | {:error, term()}
   def sql_query(pool_name, query, timeout) do
     case :poolboy.transaction(
            pool_name,
@@ -26,7 +49,7 @@ defmodule Snowflex do
   end
 
   @spec param_query(atom(), String.t(), list(query_param()), timeout()) ::
-          sql_data() | {:error, term}
+          sql_data() | {:error, term()}
   def param_query(pool_name, query, params \\ [], timeout) do
     case :poolboy.transaction(
            pool_name,

lib/snowflex/connection.ex

@@ -121,7 +121,11 @@ defmodule Snowflex.Connection do
           {:max_overflow, min_pool_size}
         ]
 
-        :poolboy.child_spec(@name, opts, {connection, @keep_alive?, @heartbeat_interval})
+        :poolboy.child_spec(@name, opts,
+          connection_args: connection,
+          keep_alive?: @keep_alive?,
+          heartbeat_interval: @heartbeat_interval
+        )
       end
 
       @impl Snowflex.Connection

lib/snowflex/worker.ex

@@ -28,7 +28,11 @@ defmodule Snowflex.Worker do
   ## GENSERVER CALL BACKS
 
   @impl GenServer
-  def init({connection_args, keep_alive?, heartbeat_interval}) do
+  def init(
+        connection_args: connection_args,
+        keep_alive?: keep_alive?,
+        heartbeat_interval: heartbeat_interval
+      ) do
     send(self(), {:start, connection_args, keep_alive?, heartbeat_interval})
     {:ok, %{backoff: :backoff.init(2, 60), state: :not_connected}}
   end

mix.exs

@@ -44,6 +44,7 @@ defmodule Snowflex.MixProject do
       {:poolboy, "~> 1.5.1"},
       {:backoff, "~> 1.1.6"},
       {:ecto, "~> 3.0"},
+      {:dialyxir, "~> 1.0", only: :dev, runtime: false},
       {:ex_doc, "~> 0.21", only: :dev, runtime: false},
       {:meck, "~> 0.9", only: :test}
     ]

mix.lock

@@ -1,9 +1,11 @@
 %{
   "backoff": {:hex, :backoff, "1.1.6", "83b72ed2108ba1ee8f7d1c22e0b4a00cfe3593a67dbc792799e8cce9f42f796b", [:rebar3], [], "hexpm", "cf0cfff8995fb20562f822e5cc47d8ccf664c5ecdc26a684cbe85c225f9d7c39"},
   "decimal": {:hex, :decimal, "2.0.0", "a78296e617b0f5dd4c6caf57c714431347912ffb1d0842e998e9792b5642d697", [:mix], [], "hexpm", "34666e9c55dea81013e77d9d87370fe6cb6291d1ef32f46a1600230b1d44f577"},
+  "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
   "earmark": {:hex, :earmark, "1.4.3", "364ca2e9710f6bff494117dbbd53880d84bebb692dafc3a78eb50aa3183f2bfd", [:mix], [], "hexpm", "8cf8a291ebf1c7b9539e3cddb19e9cef066c2441b1640f13c34c1d3cfc825fec"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.10", "6603d7a603b9c18d3d20db69921527f82ef09990885ed7525003c7fe7dc86c56", [:mix], [], "hexpm", "8e2d5370b732385db2c9b22215c3f59c84ac7dda7ed7e544d7c459496ae519c0"},
   "ecto": {:hex, :ecto, "3.5.5", "48219a991bb86daba6e38a1e64f8cea540cded58950ff38fbc8163e062281a07", [:mix], [{:decimal, "~> 1.6 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "98dd0e5e1de7f45beca6130d13116eae675db59adfa055fb79612406acf6f6f1"},
+  "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_doc": {:hex, :ex_doc, "0.23.0", "a069bc9b0bf8efe323ecde8c0d62afc13d308b1fa3d228b65bca5cf8703a529d", [:mix], [{:earmark_parser, "~> 1.4.0", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm", "f5e2c4702468b2fd11b10d39416ddadd2fcdd173ba2a0285ebd92c39827a5a16"},
   "makeup": {:hex, :makeup, "1.0.5", "d5a830bc42c9800ce07dd97fa94669dfb93d3bf5fcf6ea7a0c67b2e0e4a7f26c", [:mix], [{:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cfa158c02d3f5c0c665d0af11512fed3fba0144cf1aadee0f2ce17747fba2ca9"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.15.0", "98312c9f0d3730fde4049985a1105da5155bfe5c11e47bdc7406d88e01e4219b", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.1", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "75ffa34ab1056b7e24844c90bfc62aaf6f3a37a15faa76b07bc5eba27e4a8b4a"},

test/snowflex/worker_test.exs

@@ -8,6 +8,16 @@ defmodule Snowflex.WorkerTest do
     role: "DEV",
     warehouse: "CUSTOMER_DEV_WH"
   ]
+  @without_keep_alive [
+    connection_args: @connection_args,
+    keep_alive?: false,
+    heartbeat_interval: 10
+  ]
+  @with_keep_alive [
+    connection_args: @connection_args,
+    keep_alive?: true,
+    heartbeat_interval: 10
+  ]
 
   setup do
     :meck.new(:odbc, [:no_link])
@@ -22,15 +32,15 @@ defmodule Snowflex.WorkerTest do
     end
 
     test "does not send a heartbeat if `keep_alive?` is false" do
-      start_supervised!({Snowflex.Worker, {@connection_args, false, 10}})
+      start_supervised!({Snowflex.Worker, @without_keep_alive})
       Process.sleep(15)
 
       assert :meck.num_calls(:odbc, :sql_query, ["mock pid", 'SELECT 1']) == 0
     end
 
     test "sends heartbeat every interval if `keep_alive?` is true" do
       assert capture_log(fn ->
-               start_supervised!({Snowflex.Worker, {@connection_args, true, 10}})
+               start_supervised!({Snowflex.Worker, @with_keep_alive})
                Process.sleep(30)
              end) =~ "sending heartbeat"
 
@@ -44,7 +54,7 @@ defmodule Snowflex.WorkerTest do
 
       refute(
         capture_log(fn ->
-          worker = start_supervised!({Snowflex.Worker, {@connection_args, true, 10}})
+          worker = start_supervised!({Snowflex.Worker, @with_keep_alive})
           Process.sleep(7)
           Snowflex.Worker.sql_query(worker, "SELECT * FROM my_table")
           Process.sleep(7)
@@ -63,7 +73,7 @@ defmodule Snowflex.WorkerTest do
 
       refute(
         capture_log(fn ->
-          worker = start_supervised!({Snowflex.Worker, {@connection_args, true, 10}})
+          worker = start_supervised!({Snowflex.Worker, @with_keep_alive})
           Process.sleep(7)
 
           Snowflex.Worker.param_query(worker, "SELECT * FROM my_table WHERE name=?", [