Resell V2 API - add subnets Delete method

Add method for deleting a single subnet.
Add test and doc example.

selvpcclient/resell/v2/subnets/doc.go

@@ -39,5 +39,12 @@ Example of creating subnets
   for _, newSubnet := range newSubnets {
   	fmt.Printf("%v\n", newSubnet)
   }
+
+Example of deleting a single subnet
+
+  _, err = subnets.Delete(ctx, resellClient, subnetID)
+  if err != nil {
+    log.Fatal(err)
+  }
 */
 package subnets

selvpcclient/resell/v2/subnets/requests.go

@@ -85,3 +85,16 @@ func Create(ctx context.Context, client *selvpcclient.ServiceClient, projectID s
 
 	return result.Subnets, responseResult, nil
 }
+
+// Delete deletes a single subnet by its id.
+func Delete(ctx context.Context, client *selvpcclient.ServiceClient, id string) (*selvpcclient.ResponseResult, error) {
+	url := strings.Join([]string{client.Endpoint, resourceURL, id}, "/")
+	responseResult, err := client.DoRequest(ctx, "DELETE", url, nil)
+	if err != nil {
+		return nil, err
+	}
+	if responseResult.Err != nil {
+		err = responseResult.Err
+	}
+	return responseResult, err
+}

selvpcclient/resell/v2/subnets/testing/request_test.go

@@ -143,3 +143,22 @@ func TestCreateSubnets(t *testing.T) {
 		t.Fatalf("expected %#v, but got %#v", actualResponse, expectedResponse)
 	}
 }
+
+func TestDeleteSubnet(t *testing.T) {
+	testEnv := testutils.SetupTestEnv()
+	defer testEnv.TearDownTestEnv()
+	testEnv.NewTestResellV2Client()
+	testEnv.Mux.HandleFunc("/resell/v2/subnets/112233", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("Content-Type", "application/json")
+
+		if r.Method != http.MethodDelete {
+			t.Fatalf("expected %s method but got %s", http.MethodDelete, r.Method)
+		}
+	})
+
+	ctx := context.Background()
+	_, err := subnets.Delete(ctx, testEnv.Client, "112233")
+	if err != nil {
+		t.Fatal(err)
+	}
+}