Resell V2 - add subnets Get method

Add subnets package with Get method and basic Subnet structure.
Provide tests and doc example.

selvpcclient/resell/v2/subnets/doc.go

@@ -0,0 +1,13 @@
+/*
+Package subnets provides the ability to retrieve and manage subnets through
+the Resell v2 API.
+
+Example of getting a single subnet referenced by its id
+
+  subnet, _, err := subnets.Get(context, resellClient, subnetID)
+  if err != nil {
+    log.Fatal(err)
+  }
+  fmt.Println(subnet)
+*/
+package subnets

selvpcclient/resell/v2/subnets/requests.go

@@ -0,0 +1,33 @@
+package subnets
+
+import (
+	"context"
+	"strings"
+
+	"github.com/selectel/go-selvpcclient/selvpcclient"
+)
+
+const resourceURL = "subnets"
+
+// Get returns a single subnet by its id.
+func Get(ctx context.Context, client *selvpcclient.ServiceClient, id string) (*Subnet, *selvpcclient.ResponseResult, error) {
+	url := strings.Join([]string{client.Endpoint, resourceURL, id}, "/")
+	responseResult, err := client.DoRequest(ctx, "GET", url, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+	if responseResult.Err != nil {
+		return nil, responseResult, responseResult.Err
+	}
+
+	// Extract a subnet from the response body.
+	var result struct {
+		Subnet *Subnet `json:"subnet"`
+	}
+	err = responseResult.ExtractResult(&result)
+	if err != nil {
+		return nil, responseResult, err
+	}
+
+	return result.Subnet, responseResult, nil
+}

selvpcclient/resell/v2/subnets/schemas.go

@@ -0,0 +1,30 @@
+package subnets
+
+import "github.com/selectel/go-selvpcclient/selvpcclient/resell/v2/servers"
+
+// Subnet represents a single Resell subnet.
+type Subnet struct {
+	// ID is a unique id of a subnet.
+	ID int `json:"id"`
+
+	// Status shows if subnet is used.
+	Status string `json:"status"`
+
+	// Servers contains info about servers to which subnet is associated to.
+	Servers []servers.Server `json:"servers"`
+
+	// Region represents a region of where the subnet resides.
+	Region string `json:"region"`
+
+	// CIDR is a subnet prefix in CIDR notation.
+	CIDR string `json:"cidr"`
+
+	// NetworkID represents id of the associated network in the Networking service.
+	NetworkID string `json:"network_id"`
+
+	// SubnetID represents id of the associated subnet in the Networking service.
+	SubnetID string `json:"subnet_id"`
+
+	// ProjectID represents an associated Resell project.
+	ProjectID string `json:"project_id"`
+}

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

@@ -0,0 +1,52 @@
+package testing
+
+import (
+	"time"
+
+	"github.com/selectel/go-selvpcclient/selvpcclient/resell/v2/servers"
+	"github.com/selectel/go-selvpcclient/selvpcclient/resell/v2/subnets"
+)
+
+// TestGetSubnetResponseRaw represents a raw response from the Get request.
+const TestGetSubnetResponseRaw = `
+{
+    "subnet": {
+        "cidr": "203.0.113.11/24",
+        "id": 111122,
+        "network_id": "8233f12e-c47e-4f1c-953a-1ecd322a7119",
+        "project_id": "49338ac045f448e294b25d013f890317",
+        "region": "ru-3",
+        "servers": [
+            {
+                "id": "253b680c-89f6-4c85-afbf-c9a67c92d3fe",
+                "name": "Node01",
+                "status": "ACTIVE",
+                "updated": "2018-03-12T14:56:19Z"
+            }
+        ],
+        "status": "ACTIVE",
+        "subnet_id": "94425a6e-19cd-412d-9710-ff40b34a78f4"
+    }
+}
+`
+
+var subnetServerTimeStamp, _ = time.Parse(time.RFC3339, "2018-03-12T14:56:19Z")
+
+// TestGetSubnetResponse represents an unmarshalled TestGetSubnetResponseRaw.
+var TestGetSubnetResponse = &subnets.Subnet{
+	ID:     111122,
+	Status: "ACTIVE",
+	Servers: []servers.Server{
+		{
+			ID:      "253b680c-89f6-4c85-afbf-c9a67c92d3fe",
+			Name:    "Node01",
+			Status:  "ACTIVE",
+			Updated: subnetServerTimeStamp,
+		},
+	},
+	CIDR:      "203.0.113.11/24",
+	NetworkID: "8233f12e-c47e-4f1c-953a-1ecd322a7119",
+	ProjectID: "49338ac045f448e294b25d013f890317",
+	Region:    "ru-3",
+	SubnetID:  "94425a6e-19cd-412d-9710-ff40b34a78f4",
+}

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

@@ -0,0 +1,38 @@
+package testing
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"reflect"
+	"testing"
+
+	"github.com/selectel/go-selvpcclient/selvpcclient/resell/v2/subnets"
+	"github.com/selectel/go-selvpcclient/selvpcclient/testutils"
+)
+
+func TestGetSubnet(t *testing.T) {
+	testEnv := testutils.SetupTestEnv()
+	defer testEnv.TearDownTestEnv()
+	testEnv.NewTestResellV2Client()
+	testEnv.Mux.HandleFunc("/resell/v2/subnets/111122", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("Content-Type", "application/json")
+		fmt.Fprintf(w, TestGetSubnetResponseRaw)
+
+		if r.Method != http.MethodGet {
+			t.Fatalf("expected %s method but got %s", http.MethodGet, r.Method)
+		}
+	})
+
+	ctx := context.Background()
+	actual, _, err := subnets.Get(ctx, testEnv.Client, "111122")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := TestGetSubnetResponse
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Fatalf("expected %#v, but got %#v", expected, actual)
+	}
+}