As a developer, I want to be able to perform tasks using the framework.

- Adds Perform command to execute tasks
- Tasks should be inherited from **Amber::Tasks::Task**
- The task should declare a `perform` method. This is the method that gets
called.

spec/amber/cli/commands/perform_spec.cr

@@ -0,0 +1,36 @@
+require "../../../spec_helper"
+require "../../tasks/**"
+
+class FakeTask < Amber::Tasks::Task
+  def description
+    "Fake command task"
+  end
+
+  def perform
+    "Fake task completed!"
+  end
+end
+
+module Amber::CLI
+  describe MainCommand::Perform do
+    it "performs a tasks via command line" do
+      runner = MainCommand.run ["perform", "faketask"]
+
+      runner.should eq "Fake task completed!"
+    end
+
+    it "performs a tasks via command line alias" do
+      runner = MainCommand.run ["p", "faketask"]
+
+      runner.should eq "Fake task completed!"
+    end
+
+    it "shows task description" do
+      runner = MainCommand.run ["p", "-l", "faketask"]
+
+      runner.should eq(
+        %(FirstFakeTask\t\t #First fake task\nSecond::FakeTask\t\t #Second fake task\nFakeTask\t\t #Fake command task\n)
+      )
+    end
+  end
+end

spec/amber/tasks/runner_spec.cr

@@ -0,0 +1,61 @@
+require "../../spec_helper"
+require "../../../src/amber/tasks/**"
+
+class FirstFakeTask < Amber::Tasks::Task
+  def description
+    "First fake task"
+  end
+
+  def perform
+    "First Fake Task"
+  end
+end
+
+class Second::FakeTask < Amber::Tasks::Task
+  def perform
+    "Second Fake Task"
+  end
+
+  def description
+    "Second fake task"
+  end
+end
+
+module Amber::Tasks
+  describe Runner do
+    describe "#tasks" do
+      it "returns a list of defined tasks" do
+        Runner.tasks.should be_a Array(Task)
+        Runner.tasks.size.should eq 2
+      end
+    end
+
+    describe "#definitions" do
+      it "outputs tasks information" do
+        Runner.definitions.should eq(
+          %(FirstFakeTask\t\t #First fake task\nSecond::FakeTask\t\t #Second fake task\n)
+        )
+      end
+    end
+
+    describe "#perform" do
+      it "executes the tasks operation" do
+        runner = Runner.new("firstfaketask")
+
+        runner.perform.should eq "First Fake Task"
+      end
+
+      it "does not find find ,valid task name" do
+        runner = Runner.new("invalid_task")
+
+        runner.perform.should be_nil
+      end
+
+      it "performs namespaced task" do
+        runner = Runner.new("second::faketask")
+
+        runner.perform.should eq "Second Fake Task"
+      end
+    end
+  end
+end

src/amber/cli/commands/perform.cr

@@ -0,0 +1,29 @@
+require "icr"
+require "cli"
+
+module Amber::CLI
+  class MainCommand < ::Cli::Supercommand
+    command "p", aliased: "perform"
+
+    class Perform < ::Cli::Command
+      command_name "perform"
+
+      class Options
+        bool ["-l", "--list"], desc: "# Displays all tasks available", default: false
+        arg "task", desc: "Name of the task to execute", required: true
+      end
+
+      class Help
+        caption "# It run and performs tasks within the amber application scope"
+      end
+
+      def run
+        if options.l?
+          Amber::Tasks::Runner.definitions
+        else
+          Amber::Tasks::Runner.perform(args.task)
+        end
+      end
+    end
+  end
+end

src/amber/tasks/runner.cr

@@ -0,0 +1,38 @@
+module Amber::Tasks
+  class Runner
+    class_property tasks = [] of Amber::Tasks::Task
+    getter task : String
+
+    def self.perform(task)
+      new(task).perform
+    end
+
+    def self.definitions
+      String.build do |str|
+        tasks.each do |task|
+          str << task.class.name
+          str << "\t\t #"
+          str << task.description
+          str << "\n"
+        end
+      end
+    end
+
+    def initialize(@task : String)
+    end
+
+    def tasks
+      self.class.tasks
+    end
+
+    def perform
+      find(task).perform
+    end
+
+    private def find(lookup_task)
+      self.class.tasks.find(Amber::Tasks::NullTask.new) do |task|
+        task.class.name.downcase == lookup_task.downcase
+      end
+    end
+  end
+end

src/amber/tasks/task.cr

@@ -0,0 +1,20 @@
+module Amber::Tasks
+  abstract class Task
+    macro inherited
+      Amber::Tasks::Runner.tasks << self.new
+    end
+
+    abstract def description
+    abstract def perform
+  end
+
+  class NullTask
+    def description
+      "No Description"
+    end
+
+    def perform
+      nil
+    end
+  end
+end