moving to a new repo

about_iteration.rb

@@ -0,0 +1,93 @@
+require 'edgecase'
+
+class AboutIteration < EdgeCase::Koan
+
+  def test_each_is_a_method_on_arrays
+    [].methods.include?("each")
+  end
+
+  def test_iterating_with_each
+    array = [1, 2, 3]
+    sum = 0
+    array.each do |item|
+      sum += item
+    end
+    assert_equal 6, sum
+  end
+
+  def test_each_can_use_curly_brace_blocks_too
+    array = [1, 2, 3]
+    sum = 0
+    array.each { |item|
+      sum += item
+    }
+    assert_equal __, sum
+  end
+
+  def test_break_works_with_each_style_iterations
+    array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+    sum = 0
+    array.each { |item|
+      break if item > 3
+      sum += item
+    }
+    assert_equal __, sum
+  end
+
+  def test_collect_transforms_elements_of_an_array
+    array = [1, 2, 3]
+    new_array = array.collect { |item| item + 10 }
+    assert_equal __, new_array
+
+    # NOTE: 'map' is another name for the 'collect' operation
+    another_array = array.map { |item| item + 10 }
+    assert_equal __, another_array
+  end
+
+  def test_select_selects_certain_items_from_an_array
+    array = [1, 2, 3, 4, 5, 6]
+
+    even_numbers = array.select { |item| (item % 2) == 0 }
+    assert_equal __, even_numbers
+
+    # NOTE: 'find_all' is another name for the 'select' operation
+    more_even_numbers = array.find_all { |item| (item % 2) == 0 }
+    assert_equal __, more_even_numbers
+  end
+
+  def test_find_locates_the_first_element_matching_a_criteria
+    array = ["Jim", "Bill", "Clarence", "Doug", "Eli"]
+
+    assert_equal __, array.find { |item| item.size > 4 }
+  end
+
+  def test_inject_will_blow_your_mind
+    result = [2, 3, 4].inject(0) { |sum, item| sum + item }
+    assert_equal __, result
+
+    result2 = [2, 3, 4].inject(1) { |sum, item| sum * item }
+    assert_equal __, result2
+
+    # Extra Credit:
+    # Describe in your own words what inject does.
+  end
+
+  def test_all_iteration_methods_work_on_any_collection_not_just_arrays
+    # Ranges act like a collection
+    result = (1..3).map { |item| item + 10 }
+    assert_equal __, result
+
+    # Files act like a collection of lines
+    file = File.open("example_file.txt")
+    upcase_lines = file.map { |line| line.strip.upcase }
+    assert_equal __, upcase_lines
+
+    # NOTE: You can create your own collections that work with each,
+    # map, select, etc.
+  ensure
+    # Arg, this is ugly.
+    # We will figure out how to fix this later.
+    file.close if file
+  end
+
+end