fix reports_helper to show graph in reports/show

diff --git a/app/helpers/reports_helper.rb b/app/helpers/reports_helper.rb
index eeeb231..25ec218 100644 (file)
--- a/app/helpers/reports_helper.rb
+++ b/app/helpers/reports_helper.rb
@@ -1,7 +1,9 @@
 module ReportsHelper
 
   def gradient_intercept(expression)
-    expression.split(/x/).map(&:strip).map{|v| v.gsub(/\A[^0-9]+?|[^0-9]+?\z/, '') }
+    m = expression.scan(%r!\A(?:\(?(\-? *[0-9/ ]+?)\)? *\* *)?x(?: *(?:\+ *)?(-? *[0-9/ ]+?))?\z!).flatten
+    return %w[1 0] if m.all?(&:nil?)
+    m.map{|v| v ? v.gsub(/ */, "") : "1" }
   end
 
 end

diff --git a/spec/helpers/reports_helper_spec.rb b/spec/helpers/reports_helper_spec.rb
index 010d8a3..a4cef0a 100644 (file)
--- a/spec/helpers/reports_helper_spec.rb
+++ b/spec/helpers/reports_helper_spec.rb
@@ -1,11 +1,27 @@
 require 'spec_helper'
 
 describe ReportsHelper do
+  include ReportsHelper
 
-  #Delete this example and add some real ones or delete this file
-  it "should be included in the object returned by #helper" do
-    included_modules = (class << helper; self; end).send :included_modules
-    included_modules.should include(ReportsHelper)
+  describe "gradient_intercept" do
+    [
+     ["2 * x + 1"  , ["2", "1"]],
+     ["-2 * x + 1" , ["-2", "1"]],
+     ["2 * x - 1"  , ["2", "-1"]],
+     ["2*x+1"      , ["2", "1"]],
+     ["-2*x+1"     , ["-2", "1"]],
+     ["2*x-1"      , ["2", "-1"]],
+     ["x"          , ["1", "0"]],
+     ["x + 1"          , ["1", "1"]],
+     ["x - 1"          , ["1", "-1"]],
+     ["(1/2) * x + 1/2", ["1/2", "1/2"]],
+     ["(1 / 2) * x + 1 / 2", ["1/2", "1/2"]],
+     ["(-1 / 2) * x - 1 / 2", ["-1/2", "-1/2"]],
+    ].each do |expression, expected|
+      describe expression do
+        it{ gradient_intercept(expression).should == expected }
+      end
+    end
   end
 
 end