Add Radiant Fountain

Fixes #259

lib/magic/cards/radiant_fountain.rb

@@ -0,0 +1,23 @@
+module Magic
+  module Cards
+    RadiantFountain = Card("Radiant Fountain") do
+      type "Land"
+
+      enters_the_battlefield do
+        permanent.controller.gain_life(2)
+      end
+    end
+
+    class RadiantFountain < Card
+      def enters_tapped?
+        false
+      end
+
+      class ManaAbility < Magic::TapManaAbility
+        choices :colorless
+      end
+
+      def activated_abilities = [ManaAbility]
+    end
+  end
+end

spec/cards/radiant_fountain_spec.rb

@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+RSpec.describe Magic::Cards::RadiantFountain do
+  include_context "two player game"
+
+  let(:card) { Card("Radiant Fountain") }
+
+  let!(:permanent) do
+    p1.play_land(land: card)
+    p1.permanents.by_name("Radiant Fountain").first
+  end
+
+  it "enters the battlefield untapped" do
+    game.stack.resolve!
+    expect(permanent).not_to be_tapped
+  end
+
+  it "has the controller gain life" do
+    expect(p1.life).to eq(22)
+  end
+
+  it "taps for colorless" do
+    p1.activate_mana_ability(ability: permanent.activated_abilities.first) do
+      _1.choose(:colorless)
+    end
+
+    expect(p1.mana_pool[:colorless]).to eq(1)
+  end
+
+  it "cannot tap for another color" do
+    expect {
+      p1.activate_mana_ability(ability: permanent.activated_abilities.first) do
+        _1.choose(:blue)
+      end
+    }.to raise_error("Invalid choice made for mana ability:")
+  end
+end