allow groups to have no display name (#5020)

relax conditions on groups by allowing them to have an empty display name.

---

#### Does this PR need a docs update or release note?

- [x] ✅ Yes, it's included

#### Type of change

- [x] 🐛 Bugfix

#### Issue(s)

* Fixes #4918

#### Test Plan

- [x] 💪 Manual
- [x] ⚡ Unit test

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 - Retry transient 400 "invalidRequest" errors during onedrive & sharepoint backup.
 - Backup attachments associated with group mailbox items.
+- Groups and Teams backups no longer fail when a resource has no display name.
 
 ### Changed
 - When running `backup details` on an empty backup returns a more helpful error message.

src/pkg/services/m365/groups.go

@@ -2,12 +2,14 @@ package m365
 
 import (
 	"context"
+	"strings"
 
 	"github.com/alcionai/clues"
 	"github.com/microsoftgraph/msgraph-sdk-go/models"
 
 	"github.com/alcionai/corso/src/internal/common/ptr"
 	"github.com/alcionai/corso/src/pkg/fault"
+	"github.com/alcionai/corso/src/pkg/logger"
 	"github.com/alcionai/corso/src/pkg/services/m365/api"
 )
 
@@ -141,14 +143,23 @@ func parseGroup(ctx context.Context, mg models.Groupable) (*Group, error) {
 
 // parseGroup extracts information from `models.Teamable` we care about
 func parseGroupFromTeamable(ctx context.Context, mg models.Teamable) (*Group, error) {
-	if mg.GetDisplayName() == nil {
+	if len(ptr.Val(mg.GetId())) == 0 {
-		return nil, clues.New("group missing display name").
+		return nil, clues.New("group missing id").
 			With("group_id", ptr.Val(mg.GetId()))
 	}
 
+	if mg.GetDisplayName() == nil {
+		// logging just in case.  This shouldn't cause any issues, because
+		// idname consumers should be prepared to use the ID in place of the
+		// display name (or some other standard display).
+		logger.Ctx(ctx).
+			With("group_id", ptr.Val(mg.GetId())).
+			Info("group missing display name")
+	}
+
 	u := &Group{
-		ID:          ptr.Val(mg.GetId()),
+		ID:          strings.Clone(ptr.Val(mg.GetId())),
-		DisplayName: ptr.Val(mg.GetDisplayName()),
+		DisplayName: strings.Clone(ptr.Val(mg.GetDisplayName())),
 		IsTeam:      true,
 	}
 

src/pkg/services/m365/groups_test.go

@@ -5,10 +5,12 @@ import (
 
 	"github.com/alcionai/clues"
 	"github.com/google/uuid"
+	"github.com/microsoftgraph/msgraph-sdk-go/models"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/stretchr/testify/suite"
 
+	"github.com/alcionai/corso/src/internal/common/ptr"
 	"github.com/alcionai/corso/src/internal/tester"
 	"github.com/alcionai/corso/src/internal/tester/tconfig"
 	"github.com/alcionai/corso/src/pkg/errs"
@@ -149,3 +151,87 @@ func (suite *GroupsIntgSuite) TestSitesInGroup() {
 	assert.NoError(t, err, clues.ToCore(err))
 	assert.NotEmpty(t, sites)
 }
+
+// ---------------------------------------------------------------------------
+// unit tests
+// ---------------------------------------------------------------------------
+
+type GroupsUnitSuite struct {
+	tester.Suite
+}
+
+func TestGroupsUnitSuite(t *testing.T) {
+	suite.Run(t, &GroupsUnitSuite{Suite: tester.NewUnitSuite(t)})
+}
+
+func (suite *GroupsUnitSuite) TestParseGroupFromTeamable() {
+	id := uuid.NewString()
+	name := uuid.NewString()
+
+	table := []struct {
+		name      string
+		team      func() models.Teamable
+		expectErr assert.ErrorAssertionFunc
+		expect    Group
+	}{
+		{
+			name: "good team",
+			team: func() models.Teamable {
+				team := models.NewTeam()
+				team.SetId(ptr.To(id))
+				team.SetDisplayName(ptr.To(name))
+
+				return team
+			},
+			expectErr: assert.NoError,
+			expect: Group{
+				ID:          id,
+				DisplayName: name,
+				IsTeam:      true,
+			},
+		},
+		{
+			name: "no display name",
+			team: func() models.Teamable {
+				team := models.NewTeam()
+				team.SetId(ptr.To(id))
+
+				return team
+			},
+			expectErr: assert.NoError,
+			expect: Group{
+				ID:          id,
+				DisplayName: "",
+				IsTeam:      true,
+			},
+		},
+		{
+			name: "no id",
+			team: func() models.Teamable {
+				team := models.NewTeam()
+				team.SetDisplayName(ptr.To(name))
+
+				return team
+			},
+			expectErr: assert.Error,
+			expect:    Group{},
+		},
+	}
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			t := suite.T()
+
+			ctx, flush := tester.NewContext(t)
+			defer flush()
+
+			result, err := parseGroupFromTeamable(ctx, test.team())
+			test.expectErr(t, err, clues.ToCore(err))
+
+			if err != nil {
+				assert.Nil(t, result)
+			} else {
+				assert.Equal(t, test.expect, *result)
+			}
+		})
+	}
+}