add find_all_matching to library.

2 files changed, 14 insertions, 1 deletions

diff --git a/lib/library.rb b/lib/library.rb
index 4f1321a..f3765b5 100644
--- a/lib/library.rb
+++ b/lib/library.rb
@@ -8,4 +8,7 @@ class Library
   def contains(title)
     @books.find { |book| book.is_titled?(title) } != nil
   end
+  def find_all_matching(criteria)
+    @books.find_all {|book| criteria.is_satisfied_by book }
+  end
 end
diff --git a/test/library_specs.rb b/test/library_specs.rb
index f2972c1..ef68e4c 100644
--- a/test/library_specs.rb
+++ b/test/library_specs.rb
@@ -20,6 +20,16 @@ class TestLibrary < Test::Unit::TestCase
     assert_equal(false, @library.contains("little red riding hood"))
   end
   def test_should_be_able_to_find_all_books_by_an_author
-    
+    author = "dave thomas"
+    matches = @library.find_all_matching FindAllBooksByAuthor.new(author)
+    assert_includes(matches, @pickaxe)
+  end
+end
+class FindAllBooksByAuthor
+  def initialize(author)
+    @author = author
+  end
+  def is_satisfied_by(book)
+    book.author == @author
   end
 end