4th time

osherove-tdd-1-05-14-12.rb

@@ -0,0 +1,138 @@
+class StringCalculator
+  def self.add(input)
+    new(input).add
+  end
+
+  def initialize(input)
+    @input = input
+  end
+
+  def add
+    if valid?
+      numbers.reduce(0,:+)
+    else
+      raise "negatives not allowed: #{errors.join(",")}"
+    end
+  end
+
+  def numbers
+    lines.map {|line| line.split(delimiter)}.flatten.map(&:to_i)
+  end
+
+  def lines
+    @input.sub(%r|//(.*)|, '').split("\n")
+  end
+
+  def delimiter
+    matched = @input[%r|//(.*)|]
+    (matched && $1) || ','
+  end
+
+  def valid? 
+    numbers.all? {|n| n >= 0 }
+  end
+
+  def errors
+    numbers.select {|n| n < 0}
+  end
+end
+
+# After kata notes
+#
+# * took a few minutes extra, but completed the base kata in 35 minutes
+# * decided to not include the parser this time... not certain I like 
+#   it. I think if i had more time I would refactor to the parser again
+# * I don't like using $1 type variables, but it worked well here
+# * nice benefit to doing TDD test first: I mistakenly speced 
+#   `StringCalculator.new('1,2').must_equal 1` at one point, and the 
+#   fact that it didn't fail cued me into the error
+# * my tests got rushed at the end. not happy about that
+
+require 'minitest/autorun'
+
+describe StringCalculator do
+  it "add: returns 0 for ''" do
+    StringCalculator.add('').must_equal 0
+  end
+
+  it "add: returns 1 for '1'" do
+    StringCalculator.add('1').must_equal 1
+  end
+
+  it "add: returns 3 for '1,2'" do
+    StringCalculator.add('1,2').must_equal 3 #katanote
+  end
+
+  it "add: throws an error if negatives are included" do
+    lambda { StringCalculator.add('1,-1,2') }.must_raise RuntimeError
+  end
+
+  it "add: includes the error values if negatives are included" do
+    begin
+      StringCalculator.add('1,-1,2,-2')
+    rescue RuntimeError => e
+      e.message.must_equal "negatives not allowed: -1,-2"
+    end
+  end
+
+  it "numbers: returns [] for ''" do
+    obj = StringCalculator.new('')
+    obj.numbers.must_equal []
+  end
+
+  it "numbers: returns [1] for '1'" do
+    obj = StringCalculator.new('1')
+    obj.numbers.must_equal [1]
+  end
+
+  it "numbers: returns [1,2] for '1,2'" do
+    obj = StringCalculator.new('1,2')
+    obj.numbers.must_equal [1,2]
+  end
+
+  it "numbers: returns [1,2,3] for '1,2,3'" do
+    obj = StringCalculator.new('1,2,3')
+    obj.numbers.must_equal [1,2,3]
+  end
+
+  it "numbers: returns [1,2,3] for '1,2\n3'" do
+    obj = StringCalculator.new("1,2\n3")
+    obj.numbers.must_equal [1,2,3]
+  end
+
+  it "numbers: returns [1,2,3] for '//ab\n1\n2ab3'" do
+    obj = StringCalculator.new("//ab\n1\n2ab3")
+    obj.numbers.must_equal [1,2,3]
+  end
+
+  it "delimiter: returns ',' by default" do
+    obj = StringCalculator.new("")
+    obj.delimiter.must_equal ','
+  end
+
+  it "delimiter: switches based on the first line" do
+    obj = StringCalculator.new("//;")
+    obj.delimiter.must_equal ';'
+  end
+
+  it "delimiter: handles multi character delimiter" do
+    obj = StringCalculator.new("//ab")
+    obj.delimiter.must_equal 'ab'
+  end
+
+  it "valid?: is valid unless there are negatives" do
+    obj = StringCalculator.new("")
+    obj.valid?.must_equal true
+
+    obj = StringCalculator.new("1")
+    obj.valid?.must_equal true
+
+    obj = StringCalculator.new("-1")
+    obj.valid?.must_equal false
+  end
+
+  it "errors: returns negative numbers" do
+    obj = StringCalculator.new("1, -1, 3, -2")
+    obj.errors.must_equal [-1,-2]
+  end
+end