add + method to SortedArray

lib/sorted_containers/sorted_array.rb

@@ -50,6 +50,16 @@ def multiply(num)
     end
     alias * multiply
 
+    # Returns a new SortedArray with the values from both arrays.
+    #
+    # @param other [SortedArray] The other array to add.
+    # @return [SortedArray] The combined array.
+    def +(other)
+      new_instance = self.class.new
+      new_instance.update(to_a + other.to_a)
+      new_instance
+    end
+
     # rubocop:disable Metrics/MethodLength
 
     # Adds a value to the sorted array.

spec/sorted_array_spec.rb

@@ -27,6 +27,52 @@
     end
   end
 
+  describe "*" do
+    it "should multiply the array by the given number" do
+      array = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
+      array *= 2
+      expect(array.to_a).to eq([1, 1, 2, 2, 3, 3, 4, 4, 5, 5])
+    end
+
+    it "should multiply the array by the given large number" do
+      array = SortedContainers::SortedArray.new((1..1000).to_a)
+      array *= 2
+      expect(array.to_a).to eq(((1..1000).to_a * 2).sort)
+    end
+  end
+
+  describe "+" do
+    it "should concatenate two arrays" do
+      array1 = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
+      array2 = SortedContainers::SortedArray.new([6, 7, 8, 9, 10])
+      expect((array1 + array2).to_a).to eq([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+    end
+
+    it "should concatenate two arrays with duplicates and sort them" do
+      array1 = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
+      array2 = SortedContainers::SortedArray.new([3, 4, 5, 6, 7])
+      expect((array1 + array2).to_a).to eq([1, 2, 3, 3, 4, 4, 5, 5, 6, 7])
+    end
+
+    it "should concatenate an empty array with a non-empty array" do
+      array1 = SortedContainers::SortedArray.new
+      array2 = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
+      expect((array1 + array2).to_a).to eq([1, 2, 3, 4, 5])
+    end
+
+    it "should concatenate a non-empty array with an empty array" do
+      array1 = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
+      array2 = SortedContainers::SortedArray.new
+      expect((array1 + array2).to_a).to eq([1, 2, 3, 4, 5])
+    end
+
+    it "should concatenate two empty arrays" do
+      array1 = SortedContainers::SortedArray.new
+      array2 = SortedContainers::SortedArray.new
+      expect((array1 + array2).to_a).to eq([])
+    end
+  end
+
   describe "add" do
     it "sorts items after being added in an arbitrary order" do
       array = SortedContainers::SortedArray.new
@@ -401,20 +447,6 @@
     end
   end
 
-  describe "*" do
-    it "should multiply the array by the given number" do
-      array = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])
-      array *= 2
-      expect(array.to_a).to eq([1, 1, 2, 2, 3, 3, 4, 4, 5, 5])
-    end
-
-    it "should multiply the array by the given large number" do
-      array = SortedContainers::SortedArray.new((1..1000).to_a)
-      array *= 2
-      expect(array.to_a).to eq(((1..1000).to_a * 2).sort)
-    end
-  end
-
   describe "min" do
     it "should return the minimum value in the array" do
       array = SortedContainers::SortedArray.new([1, 2, 3, 4, 5])