Execute class definitions

lib/ahem/ast/class_definition.rb

@@ -12,4 +12,8 @@ class AST::ClassDefinition
       other.members == @members &&
       other.methods == @methods
   end
+
+  def execute(env)
+    env.set(@name.name, self)
+  end
 end

spec/ast/class_definition_spec.rb

@@ -0,0 +1,10 @@
+RSpec.describe AST::ClassDefinition do
+  it 'defines a class' do
+    env = Environment.new(env)
+    klass = AST::ClassDefinition.new(
+      AST::Identifier.new('Class'), [], []
+    )
+    klass.execute(env)
+    expect(env.get('Class')).to eq(klass)
+  end
+end