Enhance OneNote skip check (#4517)

This enhances the check that allows skipping OneNote files that cannot be downloaded
with a mime type check.

This handles cases where the folder the item is in does not have the `package` facet.

---

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

- [x] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [ ] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix a case where missing item LastModifiedTimes could cause incremental backups to fail.
 - Email size metadata was incorrectly set to the size of the last attachment.  Emails will now correctly report the size of the mail content plus the size of all attachments.
 - Improves the filtering capabilities for Groups restore and backup
+- Improve check to skip OneNote files that cannot be downloaded.
 
 ### Changed
 - Groups restore now expects the site whose backup we should restore

src/internal/m365/collection/drive/collection.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"io"
 	"net/http"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -32,6 +33,8 @@ import (
 const (
 	// Used to compare in case of OneNote files
 	MaxOneNoteFileSize = 2 * 1024 * 1024 * 1024
+
+	oneNoteMimeType = "application/msonenote"
 )
 
 var _ data.BackupCollection = &Collection{}
@@ -271,12 +274,15 @@ func (oc *Collection) getDriveItemContent(
 			return nil, clues.Wrap(err, "deleted item").Label(graph.LabelsSkippable)
 		}
 
+		var itemMimeType string
+		if item.GetFile() != nil {
+			itemMimeType = ptr.Val(item.GetFile().GetMimeType())
+		}
 		// Skip big OneNote files as they can't be downloaded
 		if clues.HasLabel(err, graph.LabelStatus(http.StatusServiceUnavailable)) &&
-			// oc.scope == CollectionScopePackage && *item.GetSize() >= MaxOneNoteFileSize {
 			// TODO: We've removed the file size check because it looks like we've seen persistent
 			// 503's with smaller OneNote files also.
-			oc.scope == CollectionScopePackage {
+			(oc.scope == CollectionScopePackage || strings.EqualFold(itemMimeType, oneNoteMimeType)) {
 			// FIXME: It is possible that in case of a OneNote file we
 			// will end up just backing up the `onetoc2` file without
 			// the one file which is the important part of the OneNote

src/internal/m365/collection/drive/collection_test.go

@@ -531,11 +531,12 @@ func (suite *GetDriveItemUnitTestSuite) TestGetDriveItem_error() {
 	strval := "not-important"
 
 	table := []struct {
-		name     string
+		name         string
-		colScope collectionScope
+		colScope     collectionScope
-		itemSize int64
+		itemSize     int64
-		labels   []string
+		itemMimeType string
-		err      error
+		labels       []string
+		err          error
 	}{
 		{
 			name:     "Simple item fetch no error",
@@ -571,6 +572,14 @@ func (suite *GetDriveItemUnitTestSuite) TestGetDriveItem_error() {
 			err:      clues.New("small onenote error").Label(graph.LabelStatus(http.StatusServiceUnavailable)),
 			labels:   []string{graph.LabelStatus(http.StatusServiceUnavailable), graph.LabelsSkippable},
 		},
+		{
+			name:         "small OneNote file",
+			colScope:     CollectionScopeFolder,
+			itemMimeType: oneNoteMimeType,
+			itemSize:     10,
+			err:          clues.New("small onenote error").Label(graph.LabelStatus(http.StatusServiceUnavailable)),
+			labels:       []string{graph.LabelStatus(http.StatusServiceUnavailable), graph.LabelsSkippable},
+		},
 		{
 			name:     "big OneNote file",
 			colScope: CollectionScopePackage,
@@ -610,6 +619,8 @@ func (suite *GetDriveItemUnitTestSuite) TestGetDriveItem_error() {
 				true,
 				false)
 
+			stubItem.GetFile().SetMimeType(&test.itemMimeType)
+
 			mbh := mock.DefaultOneDriveBH("a-user")
 			mbh.GI = mock.GetsItem{Item: stubItem}
 			mbh.GetResps = []*http.Response{{StatusCode: http.StatusOK}}