Feature/filestorage sharenetworks update (#126)

* sfs: Add update for share networks

* sfs: Add acceptance tests for share network Update

* sfs: Add possiblity to update the network for share network

* sfs: Improve share network Update unit tests

* sfs: Improve share network Update acceptance tests
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/requests.go b/openstack/sharedfilesystems/v2/sharenetworks/requests.go
index 700e703..ebaad70 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/requests.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/requests.go
@@ -123,3 +123,45 @@
 	_, r.Err = client.Get(getURL(client, id), &r.Body, nil)
 	return
 }
+
+// UpdateOptsBuilder allows extensions to add additional parameters to the
+// Update request.
+type UpdateOptsBuilder interface {
+	ToShareNetworkUpdateMap() (map[string]interface{}, error)
+}
+
+// UpdateOpts contain options for updating an existing ShareNetwork. This object is passed
+// to the sharenetworks.Update function. For more information about the parameters, see
+// the ShareNetwork object.
+type UpdateOpts struct {
+	// The share network name
+	Name string `json:"name,omitempty"`
+	// The share network description
+	Description string `json:"description,omitempty"`
+	// The UUID of the Neutron network to set up for share servers
+	NeutronNetID string `json:"neutron_net_id,omitempty"`
+	// The UUID of the Neutron subnet to set up for share servers
+	NeutronSubnetID string `json:"neutron_subnet_id,omitempty"`
+	// The UUID of the nova network to set up for share servers
+	NovaNetID string `json:"nova_net_id,omitempty"`
+}
+
+// ToShareNetworkUpdateMap assembles a request body based on the contents of an
+// UpdateOpts.
+func (opts UpdateOpts) ToShareNetworkUpdateMap() (map[string]interface{}, error) {
+	return gophercloud.BuildRequestBody(opts, "share_network")
+}
+
+// Update will update the ShareNetwork with provided information. To extract the updated
+// ShareNetwork from the response, call the Extract method on the UpdateResult.
+func Update(client *gophercloud.ServiceClient, id string, opts UpdateOptsBuilder) (r UpdateResult) {
+	b, err := opts.ToShareNetworkUpdateMap()
+	if err != nil {
+		r.Err = err
+		return
+	}
+	_, r.Err = client.Put(updateURL(client, id), b, &r.Body, &gophercloud.RequestOpts{
+		OkCodes: []int{200},
+	})
+	return
+}
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/results.go b/openstack/sharedfilesystems/v2/sharenetworks/results.go
index ce2b00b..1eb64bc 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/results.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/results.go
@@ -142,3 +142,8 @@
 type GetResult struct {
 	commonResult
 }
+
+// UpdateResult contains the response body and error from an Update request.
+type UpdateResult struct {
+	commonResult
+}
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go b/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
index 1b3cb9b..8b753e9 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
@@ -251,3 +251,57 @@
         }`)
 	})
 }
+
+func MockUpdateNeutronResponse(t *testing.T) {
+	th.Mux.HandleFunc("/share-networks/713df749-aac0-4a54-af52-10f6c991e80c", func(w http.ResponseWriter, r *http.Request) {
+		th.TestMethod(t, r, "PUT")
+		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
+		w.WriteHeader(http.StatusOK)
+		fmt.Fprintf(w, `
+            {
+                "share_network": {
+                    "name": "net_my2",
+                    "segmentation_id": null,
+                    "created_at": "2015-09-04T14:54:25.000000",
+                    "neutron_subnet_id": "new-neutron-subnet-id",
+                    "updated_at": "2015-09-07T08:02:53.512184",
+                    "id": "713df749-aac0-4a54-af52-10f6c991e80c",
+                    "neutron_net_id": "new-neutron-id",
+                    "ip_version": 4,
+                    "nova_net_id": null,
+                    "cidr": null,
+                    "project_id": "16e1ab15c35a457e9c2b2aa189f544e1",
+                    "network_type": null,
+                    "description": "new description"
+                }
+            }
+        `)
+	})
+}
+
+func MockUpdateNovaResponse(t *testing.T) {
+	th.Mux.HandleFunc("/share-networks/713df749-aac0-4a54-af52-10f6c991e80c", func(w http.ResponseWriter, r *http.Request) {
+		th.TestMethod(t, r, "PUT")
+		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
+		w.WriteHeader(http.StatusOK)
+		fmt.Fprintf(w, `
+            {
+                "share_network": {
+                    "name": "net_my2",
+                    "segmentation_id": null,
+                    "created_at": "2015-09-04T14:54:25.000000",
+                    "neutron_subnet_id": null,
+                    "updated_at": "2015-09-07T08:02:53.512184",
+                    "id": "713df749-aac0-4a54-af52-10f6c991e80c",
+                    "neutron_net_id": null,
+                    "ip_version": 4,
+                    "nova_net_id": "new-nova-id",
+                    "cidr": null,
+                    "project_id": "16e1ab15c35a457e9c2b2aa189f544e1",
+                    "network_type": null,
+                    "description": "new description"
+                }
+            }
+        `)
+	})
+}
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/testing/requests_test.go b/openstack/sharedfilesystems/v2/sharenetworks/testing/requests_test.go
index a66199f..0b28623 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/testing/requests_test.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/testing/requests_test.go
@@ -168,3 +168,72 @@
 
 	th.CheckDeepEquals(t, &expected, n)
 }
+
+// Verifies that it is possible to update a share network using neutron network
+func TestUpdateNeutron(t *testing.T) {
+	th.SetupHTTP()
+	defer th.TeardownHTTP()
+
+	MockUpdateNeutronResponse(t)
+
+	expected := sharenetworks.ShareNetwork{
+		ID:              "713df749-aac0-4a54-af52-10f6c991e80c",
+		Name:            "net_my2",
+		CreatedAt:       gophercloud.JSONRFC3339MilliNoZ(time.Date(2015, 9, 4, 14, 54, 25, 0, time.UTC)),
+		Description:     "new description",
+		NetworkType:     "",
+		CIDR:            "",
+		NovaNetID:       "",
+		NeutronNetID:    "new-neutron-id",
+		NeutronSubnetID: "new-neutron-subnet-id",
+		IPVersion:       4,
+		SegmentationID:  0,
+		UpdatedAt:       gophercloud.JSONRFC3339MilliNoZ(time.Date(2015, 9, 7, 8, 2, 53, 512184000, time.UTC)),
+		ProjectID:       "16e1ab15c35a457e9c2b2aa189f544e1",
+	}
+
+	options := sharenetworks.UpdateOpts{
+		Name:            "net_my2",
+		Description:     "new description",
+		NeutronNetID:    "new-neutron-id",
+		NeutronSubnetID: "new-neutron-subnet-id",
+	}
+
+	v, err := sharenetworks.Update(client.ServiceClient(), "713df749-aac0-4a54-af52-10f6c991e80c", options).Extract()
+	th.AssertNoErr(t, err)
+	th.CheckDeepEquals(t, &expected, v)
+}
+
+// Verifies that it is possible to update a share network using nova network
+func TestUpdateNova(t *testing.T) {
+	th.SetupHTTP()
+	defer th.TeardownHTTP()
+
+	MockUpdateNovaResponse(t)
+
+	expected := sharenetworks.ShareNetwork{
+		ID:              "713df749-aac0-4a54-af52-10f6c991e80c",
+		Name:            "net_my2",
+		CreatedAt:       gophercloud.JSONRFC3339MilliNoZ(time.Date(2015, 9, 4, 14, 54, 25, 0, time.UTC)),
+		Description:     "new description",
+		NetworkType:     "",
+		CIDR:            "",
+		NovaNetID:       "new-nova-id",
+		NeutronNetID:    "",
+		NeutronSubnetID: "",
+		IPVersion:       4,
+		SegmentationID:  0,
+		UpdatedAt:       gophercloud.JSONRFC3339MilliNoZ(time.Date(2015, 9, 7, 8, 2, 53, 512184000, time.UTC)),
+		ProjectID:       "16e1ab15c35a457e9c2b2aa189f544e1",
+	}
+
+	options := sharenetworks.UpdateOpts{
+		Name:        "net_my2",
+		Description: "new description",
+		NovaNetID:   "new-nova-id",
+	}
+
+	v, err := sharenetworks.Update(client.ServiceClient(), "713df749-aac0-4a54-af52-10f6c991e80c", options).Extract()
+	th.AssertNoErr(t, err)
+	th.CheckDeepEquals(t, &expected, v)
+}
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/urls.go b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
index 9e2c8e9..6198c54 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/urls.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
@@ -17,3 +17,7 @@
 func getURL(c *gophercloud.ServiceClient, id string) string {
 	return deleteURL(c, id)
 }
+
+func updateURL(c *gophercloud.ServiceClient, id string) string {
+	return deleteURL(c, id)
+}