Revert "Remove test for old getMountpoint"

This reverts commit 0593fe5

Author: kmarius

internal/xdg/trashdir.go

@@ -239,23 +239,25 @@ func getAllMountpoints() ([]string, error) {
 	return mountpoints, nil
 }
 
+var mountinfo_Mounted = mountinfo.Mounted
+var realpath_Realpath = realpath.Realpath
+
 // Obtain a mount point associated with a file.
 // Same as df <PATH>
 func getMountpoint(path string) (string, error) {
 
 	// iterate over the parents of the real (without symlinks) path until we find a mount point
 
-	candidate, err := realpath.Realpath(path)
+	candidate, err := realpath_Realpath(path)
 	if err != nil {
 		return "", err
 	}
 
-OUTER:
 	for {
 		// root is always mounted
 		if candidate == string(os.PathSeparator) {
 			slog.Debug("root mountpoint is detected", "path", path)
-			break OUTER
+			break
 		}
 
 		if candidate == "." {
@@ -264,8 +266,8 @@ OUTER:
 			return "", errors.New("mountpoint is '.'")
 		}
 
-		if mounted, err := mountinfo.Mounted(candidate); err == nil && mounted {
-			break OUTER
+		if mounted, err := mountinfo_Mounted(candidate); err == nil && mounted {
+			break
 		}
 
 		candidate = filepath.Dir(candidate)

internal/xdg/trashdir_test.go

@@ -0,0 +1,53 @@
+package xdg
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetMountpoint(t *testing.T) {
+	// replace to stub
+	mountinfo_Mounted = func(fpath string) (bool, error) {
+		mounts := []string{
+			"/",
+			"/foo/bar",
+			"/foo",
+			"/fooo/bar",
+			"/ffoo/bar",
+		}
+		return slices.Contains(mounts, fpath), nil
+	}
+
+	realpath_Realpath = func(path string) (string, error) {
+		return path, nil
+	}
+
+	testsNormal := []struct {
+		path string
+		want string
+	}{
+		{path: "/a.txt", want: "/"},
+		{path: "/foo/bar/a.txt", want: "/foo/bar"},
+		{path: "/foo/bar/aaa/b.txt", want: "/foo/bar"},
+		{path: "/ffoo/bar/a.txt", want: "/ffoo/bar"},
+		{path: "/aaa/bbb/ccc/ddd.txt", want: "/"},
+		{path: "/", want: "/"},
+	}
+
+	t.Run("normal", func(t *testing.T) {
+		for _, tt := range testsNormal {
+			got, err := getMountpoint(tt.path)
+			require.NoError(t, err)
+			if got != tt.want {
+				t.Errorf("getMountpoint(%q) = %q, want %q", tt.path, got, tt.want)
+			}
+		}
+	})
+
+	t.Run("error", func(t *testing.T) {
+		got, err := getMountpoint("")
+		require.Error(t, err, got)
+	})
+}