Add IO::Event::PriorityHeap#empty?.

Author: samuel-williams-shopify

lib/io/event/priority_heap.rb

@@ -27,6 +27,11 @@ def peek
 			def size
 				@contents.size
 			end
+
+			# @returns [Boolean] true if the heap is empty, false otherwise.
+			def empty?
+				@contents.empty?
+			end
 
 			# Removes and returns the smallest element in the heap, or nil if the heap is empty.
 			#

test/io/event/priority_heap.rb

@@ -20,6 +20,10 @@
 		it "should report its size as zero" do
 			expect(priority_heap.size).to be(:zero?)
 		end
+		
+		it "should report as empty" do
+			expect(priority_heap).to be(:empty?)
+		end
 	end
 
 	it "returns the same element after inserting a single element" do
@@ -29,6 +33,25 @@
 		expect(priority_heap.size).to be(:zero?)
 	end
 
+	with "#empty?" do
+		it "should return false when heap contains elements" do
+			priority_heap.push(1)
+			expect(priority_heap).not.to be(:empty?)
+		end
+		
+		it "should return true after popping all elements" do
+			priority_heap.push(1)
+			priority_heap.push(2)
+			expect(priority_heap).not.to be(:empty?)
+			
+			priority_heap.pop
+			expect(priority_heap).not.to be(:empty?)
+			
+			priority_heap.pop
+			expect(priority_heap).to be(:empty?)
+		end
+	end
+	
 	it "should return inserted elements in ascending order no matter the insertion order" do
 		(1..10).to_a.shuffle.each do |e|
 			priority_heap.push(e)