Added Formula unit test

lib/body_tracking/formula.rb

@@ -79,6 +79,7 @@ module BodyTracking
       end
     end
 
+
     class FormulaBuilder < Ripper::SexpBuilder
       def initialize(*args)
         super(*args)

test/unit/formula_test.rb

@@ -0,0 +1,28 @@
+require File.expand_path('../../test_helper', __FILE__)
+
+class FormulaTest < ActiveSupport::TestCase
+  include BodyTracking::Formula
+
+  def setup
+  end
+
+  def test_builder_parses_valid_formulas_properly
+    vector = [
+      '4', Set[], [
+        {type: :indexed, content: '4*2'}
+      ],
+
+      #'4*2'
+      #'Fats'
+      #'fats'
+    ]
+
+    vector.each_slice(3) do |formula, identifiers, parts|
+      parser = FormulaBuilder.new(formula)
+      i, p = parser.parse
+      assert_empty parser.errors
+      assert_equal identifiers, i
+      assert_equal parts, p
+    end
+  end
+end