[hw-2] add tests, coverage, benchmarks

.golangci.yaml

@@ -13,6 +13,10 @@ output:
   print-linter-name: true
 
 linters-settings:
+  gocyclo:
+    min-complexity: 15
+  gocognit:
+    min-complexity: 20
   govet:
     enable:
       - shadow
@@ -28,6 +32,8 @@ linters:
     # - dupl - it's very slow, enable if you really know why you need it
     - errcheck
     - goconst
+    - gocognit
+    - gocyclo
     - goimports
     - gosec
     - govet