Added patch and tests for issue faker-ruby/faker#94

lib/extensions/array.rb

@@ -1,7 +1,22 @@
 class Array
   unless self.method_defined? :sample
-    def sample
-      choice
+    def sample(n = nil)
+      #based on code from https://github.com/marcandre/backports
+      size = self.length
+      return self[Kernel.rand(size)] if n.nil?
+
+      n = n.to_int
+      raise ArgumentError, "negative array size" if n < 0
+
+      n = size if n > size
+
+      result = Array.new(self)
+      n.times do |i|
+        r = i + Kernel.rand(size - i)
+        result[i], result[r] = result[r], result[i]
+      end
+      result[n..size] = []
+      result
     end
   end
 end

test/test_array_sample_method_compat.rb

@@ -0,0 +1,56 @@
+require File.dirname(__FILE__) + '/test_helper.rb'
+
+# when these tests are run under Ruby 1.8.7, they will use the
+# self-defined Array#sample method in lib/extensions/array and will test whether it
+# behaves as the built-in Array#sample method from Ruby 1.9 or greater.
+# Under Ruby 1.9, they simply use the built-in Array#sample method
+class TestArraySampleMethodCompatibility < Test::Unit::TestCase
+
+  def test_returns_nil_or_empty_array_with_empty_source
+    source = []
+
+    result = source.sample
+    assert result.nil?
+
+    result = source.sample(1)
+    assert_equal result, []
+  end
+
+  def test_returns_one_array_elem_without_param
+    source = ['foo', 'bar']
+    result = source.sample
+    assert source.include? result
+  end
+
+  def test_returns_empty_array_with_param_zero
+    source = ['foo', 'bar']
+    result = source.sample(0)
+    assert_equal result, []
+  end
+
+  def test_returns_an_array_with_integer_param
+    source = ['foo', 'bar', 'baz']
+    result = source.sample(2)
+    assert result.is_a? Array
+    assert result.length == 2
+    assert((result - source).empty?)
+  end
+
+  def test_returns_source_array_with_integer_param_equal_or_bigger_than_source_length
+    source = ['foo','bar']
+    result = source.sample(2)
+    assert result.is_a? Array
+    assert((source.sort <=> result.sort) == 0)
+
+    result = source.sample(3)
+    assert result.is_a? Array
+    assert((source.sort <=> result.sort) == 0)
+  end
+
+  def test_raises_Argument_Error_with_negative_param
+    source = ['foo','bar']
+    assert_raise ArgumentError do
+      source.sample(-1)
+    end
+  end
+end