Add README

Author: danielberkompas

README.md

@@ -1,4 +1,47 @@
-EctoValidationCase
+Ecto.ValidationCase
 ==================
 
-** TODO: Add description **
+Simplify your Ecto model validation tests. Loosely inspired by [shoulda
+matchers][shoulda], but simpler.
+
+## Sample
+
+```elixir
+defmodule MyApp.UserTest do
+  use ExUnit.Case
+  use Ecto.ValidationCase, model: MyApp.User
+
+  test "requires password to be 10 chars long" do
+    rejects "password",    for: :password, message: "too short"
+    accepts "password123", for: :password
+  end
+end
+```
+
+## Rationale
+
+Rather than create a matching test helper function for each of the valiations
+that [Ecto][ecto] supports, this library intentionally keeps things simple,
+providing only `accepts/2` and `rejects/2`. Why?
+
+- It's very easy to remember, which makes validation tests more likely to be
+  written.
+- The tests are more explicit, with a minimum of magic. It is very clear exactly
+  what values are being tested, for which fields, and which error messages
+  should be returned.
+
+## Installation
+
+You can install `Ecto.ValidationCase` from hex. First, change your `deps` in
+`mix.exs`:
+
+```elixir
+def deps do
+  [{:ecto_validation_case, ">= 0.1.0"}]
+end
+```
+
+Then run `mix deps.get` to install.
+
+[ecto]: https://github.com/elixir-lang/ecto
+[shoulda]: http://matchers.shoulda.io/

lib/ecto/validation_case.ex

@@ -1,5 +1,5 @@
 defmodule Ecto.ValidationCase do
-  @shortdoc "Simplify testing Ecto validations."
+  @shortdoc "Simplify testing Ecto model validations."
 
   @moduledoc """
   Ecto.ValidationCase simplifies writing validation tests for Ecto models.
@@ -12,7 +12,7 @@ defmodule Ecto.ValidationCase do
         alias MyApp.User
 
         test "requires password to be 10 chars long" do
-          rejects "password", for: [User, :password]
+          rejects "password",    for: [User, :password], message: "too short"
           accepts "password123", for: [User, :password]
         end
       end
@@ -28,8 +28,8 @@ defmodule Ecto.ValidationCase do
 
       use Ecto.ValidationCase, model: MyApp.User
 
-  You can then leave the model out of the `for` option, and `MyApp.User` will be
-  used by default. 
+  You can then leave the model out of the `for:` option, and `MyApp.User` will 
+  be used by default. 
 
       accepts "Daniel Berkompas", for: :name