diff --git a/Gemfile.lock b/Gemfile.lock
index 90f2f48..e30b139 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,4 +1,5 @@
 GEM
+  remote: https://rubygems.org/
   specs:
     diff-lcs (1.2.5)
     rspec (3.1.0)
@@ -19,3 +20,6 @@ PLATFORMS
 
 DEPENDENCIES
   rspec
+
+BUNDLED WITH
+   1.15.0
diff --git a/lib/tree.rb b/lib/tree.rb
index 6c54019..b427888 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -1,38 +1,78 @@
 class NoApplesError < StandardError; end
 
-class AppleTree
-  attr_#fill_in :height, :age, :apples, :alive
+class Tree
+  attr_reader :height, :age, :apples, :alive
 
-  def initialize
+  def initialize(max_possible_age=10, max_growth: 3, apple_color: 'orange')
+    raise ArgumentError, 'Ages must be positive and non-zero' if max_possible_age <= 0
+    raise ArgumentError, 'Growth rates may only be positive and non-zero' if max_growth <= 0
+
+    @height = 0
+
+    @age = 0
+    @max_age = rand(1..max_possible_age)
+    @max_growth = max_growth
+
+    @apples = []
+    @apple_color = apple_color
+    @alive = true
   end
 
   def age!
+    @age += 1
+
+    if @age > @max_age
+      @alive = false
+    else
+      @height += rand(1..@max_growth)
+      add_apples
+    end
   end
 
   def add_apples
+    rand(2..8).times { @apples << make_apple }
   end
 
   def any_apples?
+    !@apples.empty?
   end
 
   def pick_an_apple!
-    raise NoApplesError, "This tree has no apples" unless self.any_apples?
+    raise NoApplesError, 'This tree has no apples' unless self.any_apples?
+    @apples.pop
   end
 
   def dead?
+    !@alive
+  end
+
+  private
+  def make_apple
+    Apple.new(@apple_color, rand(2..6))
   end
+
 end
 
 class Fruit
+  attr_reader :has_seeds
+
   def initialize
-    has_seeds = true
+    @has_seeds = true
   end
 end
 
-class Apple <
-  attr_reader #what should go here 
+class Apple < Fruit
+  attr_reader :color, :diameter
 
   def initialize(color, diameter)
+    raise ArgumentError, 'An apple must have a color' if color.nil?
+    raise ArgumentError, 'Diameter of an apple may not be negative or zero' if diameter <= 0
+    raise ArgumentError, 'Diameter must be finite' if diameter.is_a?(Float) && diameter.infinite?
+
+    super()
+
+    @color = color
+    @diameter = diameter
   end
 end
 
@@ -55,13 +95,8 @@ def tree_data
       basket << tree.pick_an_apple!
     end
 
-    diameter_sum = 0
-
-    basket.each do |apple|
-      diameter_sum += apple.diameter
-    end
-
-    avg_diameter = # It's up to you to calculate the average diameter for this harvest.
+    diameter_sum = basket.map(&:diameter).reduce :+
+    avg_diameter = diameter_sum / basket.length
 
     puts "Year #{tree.age} Report"
     puts "Tree height: #{tree.height} feet"
diff --git a/spec/tree_spec.rb b/spec/tree_spec.rb
index 99c9184..c281b1a 100644
--- a/spec/tree_spec.rb
+++ b/spec/tree_spec.rb
@@ -1,14 +1,175 @@
 require 'rspec'
 require 'tree'
 
-describe 'Tree' do
+describe Tree do
+  let(:tree) { Tree.new }
+
   it 'should be a Class' do
-    expect(described_class.is_a? 'Class').to be_true
+    expect(described_class).to be_a(Class)
+  end
+
+  it 'can age to a positive, non-zero maximum' do
+    expect { Tree.new(-1) }.to raise_error(ArgumentError)
+    expect { Tree.new(0) }.to raise_error(ArgumentError)
+
+    expect { Tree.new(1) }.not_to raise_error
+    expect { Tree.new }.not_to raise_error
+  end
+
+  it 'can grow by a positive, non-zero rate' do
+    expect { Tree.new(max_growth: -1) }.to raise_error(ArgumentError)
+    expect { Tree.new(max_growth: 0) }.to raise_error(ArgumentError)
+
+    expect { Tree.new(max_growth: 1) }.not_to raise_error
+    expect { Tree.new }.not_to raise_error
+  end
+
+  it 'starts out alive' do
+    expect(tree).not_to be_dead
+  end
+
+  it 'starts out with no apples' do
+    expect(tree.apples).to be_empty
+  end
+
+  it 'starts at age 0 with height 0 and no apples' do
+    expect(tree.age).to eq 0
+    expect(tree.height).to eq 0
+  end
+
+  it 'ages a year at a time' do
+    tree.age!
+    expect(tree.age).to eq 1
+
+    3.times { tree.age! }
+    expect(tree.age).to eq 4
+  end
+
+  it 'grows in height when it ages' do
+    tree.age!
+    expect(tree.height).to be > 0
+  end
+
+  it 'grows apples when it ages' do
+    tree.age!
+    expect(tree).to be_any_apples
+  end
+
+  it 'grows apples of a particular color' do
+    tree = Tree.new(apple_color: 'red')
+    tree.age! until tree.apples.length > 1
+
+    apple_colors = tree.apples.map &:color
+    expect(apple_colors).to all( eq 'red' )
+  end
+
+  it 'dies at a max age' do
+    tree = Tree.new 20
+
+    expect(tree).not_to be_dead
+
+    # If tree is not dead after 21 iterations then the
+    # tree is undying and that's probably impossible in reality.ss
+    until tree.dead? or tree.age > 20
+      tree.age!
+    end
+
+    expect(tree).to be_dead
+  end
+
+  it 'should continue to age in death' do
+    tree.age! until tree.dead?
+
+    start_age = tree.age
+    tree.age!
+
+    expect(tree.age - start_age).to eq 1
+
+    start_age = tree.age
+    20.times { tree.age! }
+
+    expect(tree.age - start_age).to eq 20
+  end
+
+  it 'does not grow once dead' do
+    tree.age! until tree.dead?
+
+    start_height = tree.height
+    tree.age!
+    expect(tree.height - start_height).to be_zero
+  end
+
+  it 'does not bear fruit once dead' do
+    tree.age! until tree.dead?
+    tree.pick_an_apple! while tree.any_apples?
+
+    tree.age!
+    expect(tree.apples).to be_empty
+  end
+
+  it 'provides an apple, if it has any' do
+    tree.age!
+
+    apple = tree.pick_an_apple!
+    expect(apple).not_to be nil
+    expect(apple).to be_instance_of(Apple)
+  end
+
+  it 'throws a NoApplesError when picking apples if none exists' do
+    expect { tree.pick_an_apple! }.to raise_error(NoApplesError)
+
+    tree.age!
+    tree.pick_an_apple! while tree.any_apples?
+
+    expect { tree.pick_an_apple! }.to raise_error(NoApplesError)
+  end
+
+  it 'can magically have apples added to it. By magic.' do
+    tree.add_apples
+    expect(tree.apples).not_to be_empty
   end
 end
 
-describe 'Fruit' do
+describe Fruit do
+  let(:fruit) { Fruit.new }
+
+  it 'is a Class' do
+    expect(described_class).to be_a(Class)
+  end
+
+  it 'has seeds' do
+    expect(fruit.has_seeds).to be true
+  end
 end
 
-describe 'Apple' do
+describe Apple do
+  let(:apple) { Apple.new('international orange', rand(3..10)) }
+
+  it 'is a Class' do
+    expect(described_class).to be_a(Class)
+  end
+
+  it 'is a subclass of Fruit' do
+    expect(described_class).to be < Fruit
+  end
+
+  it 'has seeds' do
+    expect(apple.has_seeds).to be true
+  end
+
+  it 'has a color' do
+    expect { Apple.new(nil, 2) }.to raise_error(ArgumentError)
+
+    expect(apple.color).not_to be_nil
+    expect(apple.color).to eq 'international orange'
+  end
+
+  it 'has a finite, positive, non-zero diameter' do
+    expect_failure = lambda { |d| expect { Apple.new('red', d) }.to raise_error(ArgumentError) }
+    expect_success = lambda { |d| expect { Apple.new('red', d) }.not_to raise_error }
+
+    [Float::INFINITY, -Float::INFINITY].each &expect_failure
+    [-1, 0].each &expect_failure
+    [1, 4, 2304].each &expect_success
+  end
 end