Fix sanity tests for exchange emails export (#4756)

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---

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

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

#### Type of change

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- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

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* #<issue>

#### Test Plan

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

src/cmd/sanity_test/common/sanitree.go

@@ -149,7 +149,7 @@ type NodeComparator[ET, EL, RT, RL any] func(
 // different data types.  The two trees are expected to represent
 // a common hierarchy.
 //
-// Additional comparisons besides the tre hierarchy are optionally
+// Additional comparisons besides the tree hierarchy are optionally
 // left to the caller by population of the NodeComparator func.
 func CompareDiffTrees[ET, EL, RT, RL any](
 	ctx context.Context,

src/cmd/sanity_test/export/exchange.go

@@ -36,12 +36,10 @@ func CheckEmailExport(
 		expect *common.Sanitree[models.MailFolderable, any],
 		result *common.Sanitree[fs.FileInfo, fs.FileInfo],
 	) {
-		modifiedExpectedLeaves := map[string]*common.Sanileaf[models.MailFolderable, any]{}
 		modifiedResultLeaves := map[string]*common.Sanileaf[fs.FileInfo, fs.FileInfo]{}
 
-		for key, val := range expect.Leaves {
+		for _, val := range expect.Leaves {
 			val.Size = 0 // we cannot match up sizes
-			modifiedExpectedLeaves[key] = val
 		}
 
 		for key, val := range result.Leaves {

src/cmd/sanity_test/restore/exchange.go

@@ -29,11 +29,12 @@ func CheckEmailRestoration(
 		"source_container_id", sourceTree.ID,
 		"source_container_name", sourceTree.Name)
 
-	common.AssertEqualTrees[models.MailFolderable, any](
+	// NOTE: We cannot compare leaves as the IDs of the restored items
+	// differ from the original ones.
+	common.CompareDiffTrees[models.MailFolderable, any](
 		ctx,
 		sourceTree,
 		restoredTree.Children[envs.SourceContainer],
-		nil,
 		nil)
 
 	common.Infof(ctx, "Success")
@@ -122,7 +123,7 @@ func recursivelyBuildTree(
 	}
 
 	for _, child := range childFolders {
-		if int(ptr.Val(child.GetTotalItemCount())) == 0 {
+		if int(ptr.Val(child.GetTotalItemCount()))+len(childFolders) == 0 {
 			common.Infof(ctx, "skipped empty folder: %s/%s", location, ptr.Val(child.GetDisplayName()))
 			continue
 		}
@@ -133,9 +134,27 @@ func recursivelyBuildTree(
 			ID:          ptr.Val(child.GetId()),
 			Name:        ptr.Val(child.GetDisplayName()),
 			CountLeaves: int(ptr.Val(child.GetTotalItemCount())),
+			Leaves:      map[string]*common.Sanileaf[models.MailFolderable, any]{},
 			Children:    map[string]*common.Sanitree[models.MailFolderable, any]{},
 		}
 
+		mails, err := ac.Mail().GetItemsInContainer(ctx, userID, c.ID)
+		if err != nil {
+			common.Fatal(ctx, "getting child containers", err)
+		}
+
+		for _, mail := range mails {
+			m := &common.Sanileaf[models.MailFolderable, any]{
+				Parent: c,
+				Self:   mail,
+				ID:     ptr.Val(mail.GetId()),
+				Name:   ptr.Val(mail.GetSubject()),
+				Size:   int64(len(ptr.Val(mail.GetBody().GetContent()))),
+			}
+
+			c.Leaves[m.ID] = m
+		}
+
 		stree.Children[c.Name] = c
 
 		recursivelyBuildTree(ctx, ac, c, userID, location+c.Name+"/")