From 6de64911fb91e7ac2dea8c5545f312c07ef88ab0 Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Sat, 22 Nov 2025 22:14:46 +0100
Subject: [PATCH] data: test TreeFinder

---
 internal/data/tree.go      |  5 ++++
 internal/data/tree_test.go | 52 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/internal/data/tree.go b/internal/data/tree.go
index e5777673f..eafb23adf 100644
--- a/internal/data/tree.go
+++ b/internal/data/tree.go
@@ -123,6 +123,7 @@ type TreeFinder struct {
 	next    func() (NodeOrError, bool)
 	stop    func()
 	current *Node
+	last    string
 }
 
 func NewTreeFinder(tree TreeNodeIterator) *TreeFinder {
@@ -139,6 +140,10 @@ func (t *TreeFinder) Find(name string) (*Node, error) {
 	if t.next == nil {
 		return nil, nil
 	}
+	if name <= t.last {
+		return nil, errors.Errorf("name %q is not greater than last name %q", name, t.last)
+	}
+	t.last = name
 	// loop until `t.current.Name` is >= name
 	for t.current == nil || t.current.Name < name {
 		current, ok := t.next()
diff --git a/internal/data/tree_test.go b/internal/data/tree_test.go
index 56752850e..ba1698227 100644
--- a/internal/data/tree_test.go
+++ b/internal/data/tree_test.go
@@ -224,6 +224,58 @@ func benchmarkLoadTree(t *testing.B, version uint) {
 	}
 }
 
+func TestTreeFinderNilIterator(t *testing.T) {
+	finder := data.NewTreeFinder(nil)
+	defer finder.Close()
+	node, err := finder.Find("foo")
+	rtest.OK(t, err)
+	rtest.Equals(t, node, nil, "finder should return nil node")
+}
+
+func TestTreeFinderError(t *testing.T) {
+	testErr := errors.New("error")
+	finder := data.NewTreeFinder(slices.Values([]data.NodeOrError{
+		{Node: &data.Node{Name: "a"}, Error: nil},
+		{Node: &data.Node{Name: "b"}, Error: nil},
+		{Node: nil, Error: testErr},
+	}))
+	defer finder.Close()
+	node, err := finder.Find("b")
+	rtest.OK(t, err)
+	rtest.Equals(t, node.Name, "b", "finder should return node with name b")
+
+	node, err = finder.Find("c")
+	rtest.Equals(t, err, testErr, "finder should return correcterror")
+	rtest.Equals(t, node, nil, "finder should return nil node")
+}
+
+func TestTreeFinderNotFound(t *testing.T) {
+	finder := data.NewTreeFinder(slices.Values([]data.NodeOrError{
+		{Node: &data.Node{Name: "a"}, Error: nil},
+	}))
+	defer finder.Close()
+	node, err := finder.Find("b")
+	rtest.OK(t, err)
+	rtest.Equals(t, node, nil, "finder should return nil node")
+	// must also be ok multiple times
+	node, err = finder.Find("c")
+	rtest.OK(t, err)
+	rtest.Equals(t, node, nil, "finder should return nil node")
+}
+
+func TestTreeFinderWrongOrder(t *testing.T) {
+	finder := data.NewTreeFinder(slices.Values([]data.NodeOrError{
+		{Node: &data.Node{Name: "d"}, Error: nil},
+	}))
+	defer finder.Close()
+	node, err := finder.Find("b")
+	rtest.OK(t, err)
+	rtest.Equals(t, node, nil, "finder should return nil node")
+	node, err = finder.Find("a")
+	rtest.Assert(t, strings.Contains(err.Error(), "is not greater than"), "unexpected error: %v", err)
+	rtest.Equals(t, node, nil, "finder should return nil node")
+}
+
 func TestFindTreeDirectory(t *testing.T) {
 	repo := repository.TestRepository(t)
 	sn := data.TestCreateSnapshot(t, repo, parseTimeUTC("2017-07-07 07:07:08"), 3)