refactor the Converters module

lib/fit4ruby/Converters.rb

@@ -21,32 +21,24 @@ module Converters
       'kg' => { 'lbs' => 2.20462262 },
       'C' => { 'F' => 9.0 / 5.0 }
     }.freeze
+
     OFFSETS = {
       'C' => { 'F' => 32 }
     }.freeze
 
     def conversion_factor(from_unit, to_unit)
       return 1.0 if from_unit == to_unit
 
-      unless FACTORS.include?(from_unit)
-        Log.fatal 'No conversion factors defined for unit ' \
-                  "'#{from_unit}' to '#{to_unit}'"
-      end
-
-      factor = FACTORS[from_unit][to_unit]
-      if factor.nil?
-        Log.fatal "No conversion factor from '#{from_unit}' to '#{to_unit}' " \
-                  'defined.'
-      end
-
-      factor
+      FACTORS.fetch(from_unit).fetch(to_unit)
+    rescue KeyError
+      Log.fatal 'No conversion factor defined ' \
+        "from unit '#{from_unit}' to unit '#{to_unit}'"
     end
 
     def conversion_offset(from_unit, to_unit)
-      return 0.0 if from_unit == to_unit || !OFFSETS.include?(from_unit) ||
-                    !OFFSETS[from_unit].include?(to_unit)
+      return 0.0 if from_unit == to_unit
 
-      OFFSETS[from_unit][to_unit]
+      OFFSETS.fetch(from_unit, {}).fetch(to_unit, 0.0)
     end
 
     def speedToPace(speed, distance = 1000.0)

spec/Converters_spec.rb

@@ -0,0 +1,74 @@
+#!/usr/bin/env ruby -w
+# encoding: UTF-8
+#
+# = Converters_spec.rb -- Fit4Ruby - FIT file processing library for Ruby
+#
+# Copyright (c) 2014, 2015 by Chris Schlaeger <cs@taskjuggler.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of version 2 of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+
+$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
+
+require 'fit4ruby/Converters'
+
+describe Fit4Ruby::Converters do
+
+  include described_class
+
+  describe '#conversion_factor' do
+
+    it 'should return one for matching "from" and "to" units' do
+      expect(conversion_factor('C', 'C')).to be(1.0)
+    end
+
+    it 'should raise an error for unsupported "from" unit' do
+      expect {
+        conversion_factor('F', 'C')
+      }.to raise_error(Fit4Ruby::Error)
+    end
+
+    it 'should raise an error for unsupported "to" unit' do
+      expect {
+        conversion_factor('C', 'K')
+      }.to raise_error(Fit4Ruby::Error)
+    end
+
+    it 'should return correct Celsius-to-Fahrenheit factor' do
+      expect(conversion_factor('C', 'F')).to eq(9.0 / 5.0)
+    end
+
+  end
+
+  describe '#conversion_offset' do
+
+    it 'should return zero for missing "from" unit' do
+      expect(conversion_offset(nil, nil)).to be_zero
+    end
+
+    it 'should return zero for missing "to" unit' do
+      expect(conversion_offset('C', nil)).to be_zero
+    end
+
+    it 'should return zero for unmapped "to" unit' do
+      expect(conversion_offset('C', 'K')).to be_zero
+    end
+
+    it 'should return zero for unmapped "from" unit' do
+      expect(conversion_offset('F', 'C')).to be_zero
+    end
+
+    it 'should return zero for matching "from"/"to" units' do
+      expect(conversion_offset('C', 'C')).to be_zero
+    end
+
+    it 'should return correct Celsius-to-Fahrenheit offset' do
+      expect(conversion_offset('C', 'F')).to eq(32)
+    end
+
+  end
+
+end
+