end
end
metaclass.class_eval do
define_method :now do
new_time
end
end
yield
end
end
end
Time.is(Time.now) do
Time.now # => Tue Nov 13 19:31:46 -0500 2007
sleep 2
Time.now # => Tue Nov 13 19:31:46 -0500 2007
end
Time.is("10/05/2006") do
Time.now # => Thu Oct 05 00:00:00 -0400 2006
sleep 2
Time.now # => Thu Oct 05 00:00:00 -0400 2006
end
UsageCalculates a sum from the elements. Examples:
payments.sum { |p| p.price * p.tax_rate }
payments.sum(&:price)
This is instead of payments.inject { |sum, p| sum + p.price }
Also calculates sums without the use of a block:
[5, 15, 10].sum # => 30
The default identity (sum of an empty list) is zero. However, you can override this default:
[].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0)
unit_tests do
test "sum the numbers from the array" do
grades = [50, 55, 67, 62, 71, 89, 84, 85, 99]
assert_equal 662, grades.sum
end
endCollect an enumerable into sets, grouped by the result of a block. Useful, for example, for grouping records by date.Usage
e.g.latest_transcripts.group_by(&:day).each do |day, transcripts|
p "#{day} -> #{transcripts.map(&:class) * ', '}"
end
"2006-03-01 -> Transcript"
"2006-02-28 -> Transcript"
"2006-02-27 -> Transcript, Transcript"
"2006-02-26 -> Transcript, Transcript"
"2006-02-25 -> Transcript"
"2006-02-24 -> Transcript, Transcript"
"2006-02-23 -> Transcript"
unit_tests do
test "group by grades" do
grades = [50, 55, 60, 62, 71, 83, 84, 85, 99]
expected = {"A"=>[99], "B"=>[83, 84, 85], "C"=>[71], "D"=>[60, 62], "F"=>[50, 55]}
actual = grades.group_by do |grade|
case
when grade < 60 then "F"
when grade < 70 then "D"
when grade < 80 then "C"
when grade < 90 then "B"
else "A"
end
end
assert_equal expected, actual
end
end
private
" victims are no longer with us."
end
end
saved_private_instance_methods = self.private_instance_methods
self.class_eval {public *saved_private_instance_methods }
yield
self.class_eval {private *saved_private_instance_methods }
end
end
unit_tests do
test "kill returns a murder string" do
Ninja.publicize_methods do
assert_equal '3 victims are no longer with us.', Ninja.new.kill(3)
end
end
endUsageConvert an enumerable to a hash. Examples:
people.index_by(&:login)
=> { "nextangle" =>, "chade-" => , ...}
people.index_by { |person| "#{person.first_name} #{person.last_name}" }
=> { "Chade- Fowlersburg-e" =>, "David Heinemeier Hansson" => , ...}
array = [1..100].to_anote: we couldn't use the
hash = array.index_by { |element| element }
array_bm = Benchmark.measure do
array.find { |element| element = 99 }
end
hash_bm = Benchmark.measure do
hash.include? 99
end
p array_bm.real # => 1.382
p hash_bm.real # => 1.001
include? method for our particular instance, so I left it out of the contrived example.
unit_tests do
test "index by highest numeric per grade level" do
grades = [50, 55, 67, 62, 71, 89, 84, 85, 99]
expected = {"A"=>99, "B"=>89, "C"=>71, "D"=>67, "F"=>55}
actual = grades.sort.index_by do |grade|
case
when grade < 60 then "F"
when grade < 70 then "D"
when grade < 80 then "C"
when grade < 90 then "B"
else "A"
end
end
assert_equal expected, actual
end
end<% @customers.each_with_index do |customer, index| %>
<div style="color:<%= index.even? ? "white" : "gray" %>">
<%= customer.name %>
</div>
<% end %>
unit_tests do
test "10 is even?" do
assert_equal true, 10.even?
end
endYields a single-character string for each character in the string. When $KCODE = ‘UTF8’, multi-byte characters are yielded appropriately.Usage
unit_tests do
test "each_char can be used to strip every other charater" do
strip, result = true, ""
"hello world".each_char do |char|
result << char if strip
strip = !strip
end
assert_equal "hlowrd", result
end
end
unit_tests do
test "find the difference between two hashes" do
assert_equal({:b=>3}, {:a => 1, :b => 3}.diff({:a=>1}))
end
endConstantize tries to find a declared constant with the name specified in the string. It raises a NameError when the name is not in CamelCase or is not initialized.Usage
Examples
- "Module".constantize #=> Module
- "Class".constantize #=> Class
unit_tests do
end
test "constantize a string representation of a class" do
assert_equal Klass, "Klass".constantize
end
endCreate a class name from a table name like Rails does for table names to models. Note that this returns a string and not a Class. (To convert to an actual class follow classify with constantize.)Usage
Examples
- "egg_and_hams".classify #=> "EggAndHam"
- "post".classify #=> "Post"
unit_tests do
test "singularize and camelize a string via classify" do
assert_equal "Name", "names".classify
end
endThe reverse of pluralize, returns the singular form of a word in a string.Usage
Examples
- "posts".singularize #=> "post"
- "octopi".singularize #=> "octopus"
- "sheep".singluarize #=> "sheep"
- "word".singluarize #=> "word"
- "the blue mailmen".singularize #=> "the blue mailman"
- "CamelOctopi".singularize #=> "CamelOctopus"
unit_tests do
test "change plural word to singular word" do
assert_equal "class_name", "class_names".singularize
end
end
include Validatable
validates_presence_of :name, :address
attr_accessor :name, :address
end
unit_tests do
test "individual validation for name is executed" do
instance = SampleModel.new
instance.validate_only("presence_of/name")
assert_equal "can't be empty", instance.errors.on(:name)
end
test "individual validation for address is not executed" do
instance = SampleModel.new
instance.validate_only("presence_of/name")
assert_equal nil, instance.errors.on(:address)
end
endvalidates_presence_of :name can be run with obj.validate_only("presence_of/name")validates_presence_of :birthday, :key => "a key" can be run with obj.validate_only("presence_of/a key")