feat: generate task model and make unit tests pass.

app/models/task.rb

@@ -0,0 +1,3 @@
+class Task < ApplicationRecord
+  validates :action, presence: true, uniqueness: true
+end

db/migrate/20190627172238_create_tasks.rb

@@ -0,0 +1,11 @@
+class CreateTasks < ActiveRecord::Migration[5.2]
+  def change
+    create_table :tasks do |t|
+      t.string :action
+      t.boolean :done, default: false
+      t.datetime :finished_at
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -0,0 +1,26 @@
+# This file is auto-generated from the current state of the database. Instead
+# of editing this file, please use the migrations feature of Active Record to
+# incrementally modify your database, and then regenerate this schema definition.
+#
+# Note that this schema.rb definition is the authoritative source for your
+# database schema. If you need to create the application database on another
+# system, you should be using db:schema:load, not running all the migrations
+# from scratch. The latter is a flawed and unsustainable approach (the more migrations
+# you'll amass, the slower it'll run and the greater likelihood for issues).
+#
+# It's strongly recommended that you check this file into your version control system.
+
+ActiveRecord::Schema.define(version: 2019_06_27_172238) do
+
+  # These are extensions that must be enabled in order to support this database
+  enable_extension "plpgsql"
+
+  create_table "tasks", force: :cascade do |t|
+    t.string "action"
+    t.boolean "done", default: false
+    t.datetime "finished_at"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+end

spec/models/task_spec.rb

@@ -10,7 +10,7 @@
   end
   it "has an action" do
     task = Task.new(valid_attributes)
-    expect(task.action).to eq("Finish Unit tests")
+    expect(task.action).to eq("Finish unit tests")
   end
   it "it has a done property that defaults to false" do
     task = Task.new(valid_attributes)
@@ -22,7 +22,7 @@
   end
   it "is only valid if the action is unique and present" do
     Task.create!(valid_attributes)
-    task = Task.new(action: "Finish Unit tests")
+    task = Task.new(action: "Finish unit tests")
 
     expect(task).not_to be_valid
   end