spec/beethoven/composer_spec.rb in beethoven-0.0.2 vs spec/beethoven/composer_spec.rb in beethoven-0.1.0

@@ -1,4 +1,42 @@
 require 'beethoven/composer'
 
 RSpec.describe Beethoven::Composer do
+  # F :: () -> a
+  class F
+    attr_reader :a
+
+    def initialize(o)
+      @a = o
+    end
+  end
+
+  # G :: a -> b
+  class G
+    attr_reader :b
+
+    def initialize(o)
+      @b = o.a
+    end
+  end
+
+  # H :: b -> c
+  class H
+    attr_reader :c
+
+    def initialize(o)
+      @c = o.b
+    end
+  end
+
+  subject { Beethoven::Composer }
+
+  describe 'composes classes' do
+    it 'transfers the value' do
+      expect(subject.new(F, G, H).new(5).c).to eq(5)
+    end
+
+    it 'can take array of classes' do
+      expect(subject.new([F, G, H]).new(5).c).to eq(5)
+    end
+  end
 end