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Diffstat (limited to 'spec/ruby/core/enumerable/max_by_spec.rb')
-rw-r--r-- | spec/ruby/core/enumerable/max_by_spec.rb | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/spec/ruby/core/enumerable/max_by_spec.rb b/spec/ruby/core/enumerable/max_by_spec.rb new file mode 100644 index 0000000000..4058cf0a40 --- /dev/null +++ b/spec/ruby/core/enumerable/max_by_spec.rb @@ -0,0 +1,81 @@ +require File.expand_path('../../../spec_helper', __FILE__) +require File.expand_path('../fixtures/classes', __FILE__) +require File.expand_path('../shared/enumerable_enumeratorized', __FILE__) + +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 + lambda { @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 |