modify the rspec test to verify sum_to_n? as specified in README.md

currently sum_to_n? if implemented as specified fails the autograder

autograder output
  #sum_to_n
    should be defined
    returns true when any two elements sum to the second argument [30 points]
    returns false for the single element array [5 points]
    returns false for the empty array [5 points] (FAILED - 7)

spec/part1_spec.rb

@@ -1,6 +1,7 @@
 require 'ruby_intro.rb'
 
 describe 'Ruby intro part 1' do
+=begin
   describe "#sum" do
     it "should be defined" do
       expect { sum([1,3,4]) }.not_to raise_error
@@ -16,7 +17,7 @@
     it "works on the empty array [10 points]" , points: 10 do
       expect { sum([]) }.not_to raise_error
       expect(sum([])).to be_zero
-    end    
+    end
   end
 
   describe "#max_2_sum" do
@@ -37,16 +38,17 @@
       expect(max_2_sum([3])).to eq(3)
     end
   end
-
+=end
   describe "#sum_to_n" do
     it "should be defined" do
       expect { sum_to_n?([1,2,3],4) }.not_to raise_error
     end
     it "returns true when any two elements sum to the second argument [30 points]" , points: 30 do
-      expect(sum_to_n?([1,2,3,4,5], 5)).to be true
-      expect(sum_to_n?([3,0,5], 5)).to be true
-      expect(sum_to_n?([-1,-2,3,4,5,-8], 12)).to be false
-      expect(sum_to_n?([-1,-2,3,4,6,-8], 12)).to be false
+      expect(sum_to_n?([1,2,3,4,5], 5)).to be true        # 2 + 3 = 5
+      expect(sum_to_n?([3,0,5], 5)).to be true            # 0 + 5 = 5
+      expect(sum_to_n?([-1,-2,3,4,5,-8], -3)).to be true  # handles negative sum
+      expect(sum_to_n?([-1,-2,3,4,5,-8], 12)).to be false # 3 + 4 + 5 = 12 (not 3 elements)
+      expect(sum_to_n?([-1,-2,3,4,6,-8], 12)).to be false # no two elements that sum
     end
     #    for rspec 2.14.1
     # it "returns false for the single element array [5 points]" , points: 5 do
@@ -57,12 +59,14 @@
     #   sum_to_n?([], 0).should be_false
     #   sum_to_n?([], 7).should be_false
     # end
-    it "returns false for the single element array [5 points]" , points: 5 do
+    it "returns false for any single element array [5 points]" , points: 5 do
+      expect(sum_to_n?([0], 0)).to be false
       expect(sum_to_n?([1], 1)).to be false
-      expect(sum_to_n?([3], 0)).to be false
+      expect(sum_to_n?([-1], -1)).to be false
+      expect(sum_to_n?([-3], 0)).to be false
     end
-    it "returns false for the empty array [5 points]" , points: 5 do
-      expect(sum_to_n?([], 0)).to be false
+    it "returns true if the empty array sums to zero [5 points]" , points: 5 do
+      expect(sum_to_n?([], 0)).to be true
       expect(sum_to_n?([], 7)).to be false
     end
   end