tailscale: guard last_seen nil and add tests

Adds last_seen nil check to deviceToMap
Adds unit tests covering new data_source device fields

Signed-off-by: Zach Buchheit <zachb@tailscale.com>

Author: zbuchheit

tailscale/data_source_device.go

@@ -193,6 +193,13 @@ func dataSourceDeviceRead(ctx context.Context, d *schema.ResourceData, m interfa
 // resource in Terraform. This omits the "id" which is expected to be set
 // using [schema.ResourceData.SetId].
 func deviceToMap(device *tailscale.Device) map[string]any {
+	var lastSeen string
+	if device.LastSeen == nil {
+		lastSeen = ""
+	} else {
+		lastSeen = device.LastSeen.Format(time.RFC3339)
+	}
+
 	return map[string]any{
 		"name":                        device.Name,
 		"hostname":                    device.Hostname,
@@ -207,7 +214,7 @@ func deviceToMap(device *tailscale.Device) map[string]any {
 		"created":                     device.Created.Format(time.RFC3339),
 		"expires":                     device.Expires.Format(time.RFC3339),
 		"is_external":                 device.IsExternal,
-		"last_seen":                   device.LastSeen.Format(time.RFC3339),
+		"last_seen":                   lastSeen,
 		"machine_key":                 device.MachineKey,
 		"node_key":                    device.NodeKey,
 		"os":                          device.OS,

tailscale/data_source_device_test.go

@@ -0,0 +1,116 @@
+package tailscale
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	tsclient "tailscale.com/client/tailscale/v2"
+	"tailscale.com/tstest"
+)
+
+func TestDeviceToMap(t *testing.T) {
+	t.Parallel()
+	cl := tstest.NewClock(tstest.ClockOpts{})
+	created := tsclient.Time{Time: cl.Now().Truncate(time.Second)}
+	expires := tsclient.Time{Time: cl.Now().Truncate(time.Second).Add(24 * time.Hour)}
+	lastSeen := tsclient.Time{Time: cl.Now().Truncate(time.Second).Add(-5 * time.Minute)}
+
+	dev := &tsclient.Device{
+		Name:                      "host.example.ts.net",
+		Hostname:                  "host",
+		User:                      "user@example.com",
+		NodeID:                    "node-123",
+		Addresses:                 []string{"100.100.100.101", "fd7a:115c:a1e0::1"},
+		Tags:                      []string{"tag:test1", "tag:test2"},
+		Authorized:                true,
+		KeyExpiryDisabled:         true,
+		BlocksIncomingConnections: true,
+		ClientVersion:             "1.88.4",
+		Created:                   created,
+		Expires:                   expires,
+		IsExternal:                false,
+		LastSeen:                  &lastSeen,
+		MachineKey:                "machine-key",
+		NodeKey:                   "node-key",
+		OS:                        "linux",
+		UpdateAvailable:           true,
+		TailnetLockError:          "lock-error",
+		TailnetLockKey:            "lock-key",
+	}
+
+	m := deviceToMap(dev)
+
+	assert.Equal(t, dev.Name, m["name"].(string))
+	assert.Equal(t, dev.Hostname, m["hostname"].(string))
+	assert.Equal(t, dev.User, m["user"].(string))
+	assert.Equal(t, dev.NodeID, m["node_id"].(string))
+	assert.Equal(t, dev.Addresses, m["addresses"].([]string))
+	assert.Equal(t, dev.Tags, m["tags"].([]string))
+	assert.Equal(t, dev.Authorized, m["authorized"].(bool))
+	assert.Equal(t, dev.KeyExpiryDisabled, m["key_expiry_disabled"].(bool))
+	assert.Equal(t, dev.BlocksIncomingConnections, m["blocks_incoming_connections"].(bool))
+	assert.Equal(t, dev.ClientVersion, m["client_version"].(string))
+	assert.Equal(t, created.Format(time.RFC3339), m["created"].(string))
+	assert.Equal(t, expires.Format(time.RFC3339), m["expires"].(string))
+	assert.Equal(t, dev.IsExternal, m["is_external"].(bool))
+	assert.Equal(t, lastSeen.Format(time.RFC3339), m["last_seen"].(string))
+	assert.Equal(t, dev.MachineKey, m["machine_key"].(string))
+	assert.Equal(t, dev.NodeKey, m["node_key"].(string))
+	assert.Equal(t, dev.OS, m["os"].(string))
+	assert.Equal(t, dev.UpdateAvailable, m["update_available"].(bool))
+	assert.Equal(t, dev.TailnetLockError, m["tailnet_lock_error"].(string))
+	assert.Equal(t, dev.TailnetLockKey, m["tailnet_lock_key"].(string))
+}
+func TestDeviceToMap_LastSeenNil(t *testing.T) {
+	t.Parallel()
+	cl := tstest.NewClock(tstest.ClockOpts{})
+	created := tsclient.Time{Time: cl.Now().Truncate(time.Second)}
+	expires := tsclient.Time{Time: cl.Now().Truncate(time.Second).Add(24 * time.Hour)}
+
+	dev := &tsclient.Device{
+		Name:                      "host.example.ts.net",
+		Hostname:                  "host",
+		User:                      "user@example.com",
+		NodeID:                    "node-123",
+		Addresses:                 []string{"100.100.100.101", "fd7a:115c:a1e0::1"},
+		Tags:                      []string{"tag:test1", "tag:test2"},
+		Authorized:                true,
+		KeyExpiryDisabled:         true,
+		BlocksIncomingConnections: true,
+		ClientVersion:             "1.88.4",
+		Created:                   created,
+		Expires:                   expires,
+		IsExternal:                false,
+		LastSeen:                  nil,
+		MachineKey:                "machine-key",
+		NodeKey:                   "node-key",
+		OS:                        "linux",
+		UpdateAvailable:           true,
+		TailnetLockError:          "lock-error",
+		TailnetLockKey:            "lock-key",
+	}
+
+	m := deviceToMap(dev)
+
+	assert.Equal(t, dev.Name, m["name"].(string))
+	assert.Equal(t, dev.Hostname, m["hostname"].(string))
+	assert.Equal(t, dev.User, m["user"].(string))
+	assert.Equal(t, dev.NodeID, m["node_id"].(string))
+	assert.Equal(t, dev.Addresses, m["addresses"].([]string))
+	assert.Equal(t, dev.Tags, m["tags"].([]string))
+	assert.Equal(t, dev.Authorized, m["authorized"].(bool))
+	assert.Equal(t, dev.KeyExpiryDisabled, m["key_expiry_disabled"].(bool))
+	assert.Equal(t, dev.BlocksIncomingConnections, m["blocks_incoming_connections"].(bool))
+	assert.Equal(t, dev.ClientVersion, m["client_version"].(string))
+	assert.Equal(t, created.Format(time.RFC3339), m["created"].(string))
+	assert.Equal(t, expires.Format(time.RFC3339), m["expires"].(string))
+	assert.Equal(t, dev.IsExternal, m["is_external"].(bool))
+	assert.Equal(t, "", m["last_seen"]) // Expect empty string for nil LastSeen
+	assert.Equal(t, dev.MachineKey, m["machine_key"].(string))
+	assert.Equal(t, dev.NodeKey, m["node_key"].(string))
+	assert.Equal(t, dev.OS, m["os"].(string))
+	assert.Equal(t, dev.UpdateAvailable, m["update_available"].(bool))
+	assert.Equal(t, dev.TailnetLockError, m["tailnet_lock_error"].(string))
+	assert.Equal(t, dev.TailnetLockKey, m["tailnet_lock_key"].(string))
+}