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require_relative '../../spec_helper'
require_relative 'fixtures/classes'
require_relative 'shared/enumerable_enumeratorized'
describe "Enumerable#max_by" do
it "returns an enumerator if no block" do
EnumerableSpecs::Numerous.new(42).max_by.should be_an_instance_of(Enumerator)
end
it "returns nil if #each yields no objects" do
EnumerableSpecs::Empty.new.max_by {|o| o.nonesuch }.should == nil
end
it "returns the object for whom the value returned by block is the largest" do
EnumerableSpecs::Numerous.new(*%w[1 2 3]).max_by {|obj| obj.to_i }.should == '3'
EnumerableSpecs::Numerous.new(*%w[three five]).max_by {|obj| obj.length }.should == 'three'
end
it "returns the object that appears first in #each in case of a tie" do
a, b, c = '1', '2', '2'
EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj.to_i }.should equal(b)
end
it "uses max.<=>(current) to determine order" do
a, b, c = (1..3).map{|n| EnumerableSpecs::ReverseComparable.new(n)}
# Just using self here to avoid additional complexity
EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj }.should == a
end
it "is able to return the maximum for enums that contain nils" do
enum = EnumerableSpecs::Numerous.new(nil, nil, true)
enum.max_by {|o| o.nil? ? 0 : 1 }.should == true
enum.max_by {|o| o.nil? ? 1 : 0 }.should == nil
end
it "gathers whole arrays as elements when each yields multiple" do
multi = EnumerableSpecs::YieldsMulti.new
multi.max_by {|e| e.size}.should == [6, 7, 8, 9]
end
it_behaves_like :enumerable_enumeratorized_with_origin_size, :max_by
context "when called with an argument n" do
before :each do
@enum = EnumerableSpecs::Numerous.new(101, 55, 1, 20, 33, 500, 60)
end
context "without a block" do
it "returns an enumerator" do
@enum.max_by(2).should be_an_instance_of(Enumerator)
end
end
context "with a block" do
it "returns an array containing the maximum n elements based on the block's value" do
result = @enum.max_by(3) { |i| i.to_s }
result.should == [60, 55, 500]
end
context "on a enumerable of length x where x < n" do
it "returns an array containing the maximum n elements of length n" do
result = @enum.max_by(500) { |i| i.to_s }
result.length.should == 7
end
end
context "when n is negative" do
it "raises an ArgumentError" do
-> { @enum.max_by(-1) { |i| i.to_s } }.should raise_error(ArgumentError)
end
end
end
context "when n is nil" do
it "returns the maximum element" do
@enum.max_by(nil) { |i| i.to_s }.should == 60
end
end
end
end
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