Introduce test_myxql env

In order to test code with both postgreqsl and myxql adapters, we use
a separate MIX_ENV `test_myxql`.

* test Repo adapter is determined at compile time.
* docker-compose-test adds a MySQL container
* to run the tests with myxql adapter, simply run `MIX_ENV=test_myxql
  mix test`

README.md

@@ -53,6 +53,15 @@ defmodule MyApp.Repo.Migrations.CreateJobQueue do
 end
 ```
 
+### Compatibility
+
+`EctoJob` leverages specific PostgreSQL features, like notification mechanism
+when inserting a new job into a queue.
+
+However, a non-optimized version of `EctoJob` can be used on top of MySQL >=
+8.0.1. Prior version of MySQL is not supported because of the following feature:
+* `FOR UPDATE SKIP LOCKED`
+
 ### Upgrading to version 3.0
 
 To upgrade your project to 3.0 version of `ecto_job` you must add a migration to update the pre-existent job queue tables:

config/config.exs

@@ -19,3 +19,19 @@ if Mix.env() == :test do
 
   config :logger, level: :warn
 end
+
+if Mix.env() == :test_myxql do
+  config :ecto_job, EctoJob.Test.Repo,
+    adapter: Ecto.Adapters.MyXQL,
+    username: "mysql",
+    password: "password",
+    database: "ecto_job_test",
+    hostname: "localhost",
+    port: 13306,
+    pool: Ecto.Adapters.SQL.Sandbox,
+    priv: "test/support/"
+
+  config :ecto_job, ecto_repos: [EctoJob.Test.Repo]
+
+  config :logger, level: :warn
+end

docker-compose-test.yml

@@ -9,3 +9,14 @@ services:
       - POSTGRES_USER=postgres
       - POSTGRES_PASSWORD=password
       - POSTGRES_DB=ecto_job_test
+
+  ecto-job-test-mysql:
+    image: mysql:latest
+    ports:
+      - "13306:3306"
+    environment:
+      - MYSQL_USER=mysql
+      - MYSQL_PASSWORD=password
+      - MYSQL_DATABASE=ecto_job_test
+      - MYSQL_ROOT_PASSWORD=mysql
+      - MYSQL_ROOT_HOST=%

mix.exs

@@ -21,10 +21,14 @@ defmodule EctoJob.Mixfile do
   end
 
   def application do
-    [extra_applications: [:logger]]
+    [extra_applications: [:logger] ++ extra_applications(Mix.env())]
   end
 
-  defp elixirc_paths(:test), do: ["lib", "test/support"]
+  defp extra_applications(:test), do: [:postgrex]
+  defp extra_applications(:test_myxql), do: [:myxql]
+  defp extra_applications(_), do: []
+
+  defp elixirc_paths(test) when test in [:test, :test_myxql], do: ["lib", "test/support"]
   defp elixirc_paths(_), do: ["lib"]
 
   defp package do
@@ -56,7 +60,8 @@ defmodule EctoJob.Mixfile do
   defp deps do
     [
       {:ecto_sql, "~> 3.2"},
-      {:postgrex, "~> 0.15"},
+      {:postgrex, "~> 0.15", optional: true},
+      {:myxql, "~> 0.2", optional: true},
       {:jason, "~> 1.0"},
       {:gen_stage, "~> 1.0"},
       {:credo, "~> 1.0", only: :dev, runtime: false},

mix.lock

@@ -15,6 +15,7 @@
   "jason": {:hex, :jason, "1.1.2", "b03dedea67a99223a2eaf9f1264ce37154564de899fd3d8b9a21b1a6fd64afe7", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "fdf843bca858203ae1de16da2ee206f53416bbda5dc8c9e78f43243de4bc3afe"},
   "makeup": {:hex, :makeup, "1.0.0", "671df94cf5a594b739ce03b0d0316aa64312cee2574b6a44becb83cd90fb05dc", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "a10c6eb62cca416019663129699769f0c2ccf39428b3bb3c0cb38c718a0c186d"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.14.0", "cf8b7c66ad1cff4c14679698d532f0b5d45a3968ffbcbfd590339cb57742f1ae", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "d4b316c7222a85bbaa2fd7c6e90e37e953257ad196dc229505137c5e505e9eff"},
+  "myxql": {:hex, :myxql, "0.2.10", "18fb7ce67dd8ab6f5672e94a944ae90157231b637db14fc92ab77c50e33cd83a", [:mix], [{:db_connection, "~> 2.0", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.6", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "b9d48449845378693dca7367694cbd75a192d5674bf7d19ca4c924c96818d275"},
   "nimble_parsec": {:hex, :nimble_parsec, "0.5.1", "c90796ecee0289dbb5ad16d3ad06f957b0cd1199769641c961cfe0b97db190e0", [:mix], [], "hexpm", "00e3ebdc821fb3a36957320d49e8f4bfa310d73ea31c90e5f925dc75e030da8f"},
   "poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [:mix], [], "hexpm"},
   "postgrex": {:hex, :postgrex, "0.15.1", "23ce3417de70f4c0e9e7419ad85bdabcc6860a6925fe2c6f3b1b5b1e8e47bf2f", [:mix], [{:connection, "~> 1.0", [hex: :connection, repo: "hexpm", optional: false]}, {:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "12cd418e207b8ed787dfe0f520fccd6c001f58d9108233feae7df36462593d1f"},

test/support/repo.ex

@@ -1,3 +1,4 @@
 defmodule EctoJob.Test.Repo do
-  use Ecto.Repo, otp_app: :ecto_job, adapter: Ecto.Adapters.Postgres
+  adapter = Application.compile_env!(:ecto_job, __MODULE__)[:adapter]
+  use Ecto.Repo, otp_app: :ecto_job, adapter: adapter
 end