[MM-60888] Fix: Retention can cause unrelated files to be deleted (#29897)

* fix for deleting non-bulk export files and directories

* add job worker setup and running to helper_test.go

* add infrastructure for e2e testing of workers; test ExportDelete

* linting

* use retention days in test instead of magic number

server/channels/jobs/export_delete_test.go

@@ -0,0 +1,102 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package jobs_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestExportDelete(t *testing.T) {
+	// Create a temporary export directory
+	fileSettingsDir, err := os.MkdirTemp("", "")
+	require.NoError(t, err)
+	relExportDir := "./export"
+	exportDir := filepath.Join(fileSettingsDir, relExportDir)
+
+	t.Cleanup(func() {
+		err = os.RemoveAll(fileSettingsDir)
+		assert.NoError(t, err)
+	})
+
+	retentionDays := 1
+
+	updateConfig := func(cfg *model.Config) {
+		*cfg.FileSettings.DriverName = model.ImageDriverLocal
+		*cfg.FileSettings.Directory = fileSettingsDir
+		*cfg.ExportSettings.Directory = relExportDir
+		*cfg.ExportSettings.RetentionDays = retentionDays
+	}
+
+	th := SetupWithUpdateCfg(t, updateConfig)
+	defer th.TearDown()
+
+	// Create test files with different timestamps
+	files := []string{
+		"old_export.zip",
+		"recent_export.zip",
+		"normal.txt",
+		"test_export.zip",
+		"data.json",
+	}
+
+	// Create directories that should not be deleted
+	dirs := []string{
+		"data",
+		"data/subfolder",
+	}
+
+	for _, dir := range dirs {
+		err = os.MkdirAll(filepath.Join(exportDir, dir), 0755)
+		require.NoError(t, err)
+		// Add a file in each directory that should not be deleted
+		err = os.WriteFile(filepath.Join(exportDir, dir, "file.txt"), []byte("test"), 0644)
+		require.NoError(t, err)
+	}
+
+	for _, file := range files {
+		err = os.WriteFile(filepath.Join(exportDir, file), []byte("test"), 0644)
+		require.NoError(t, err)
+	}
+
+	// Set old timestamps for files that should be deleted
+	oldTime := time.Now().Add(-(time.Duration(retentionDays) * 24 * time.Hour) - 1*time.Hour)
+	err = os.Chtimes(filepath.Join(exportDir, "old_export.zip"), oldTime, oldTime)
+	require.NoError(t, err)
+	err = os.Chtimes(filepath.Join(exportDir, "test_export.zip"), oldTime, oldTime)
+	require.NoError(t, err)
+
+	// Start the workers
+	th.SetupWorkers(t)
+
+	// Run the export delete job
+	th.RunJob(t, model.JobTypeExportDelete, nil)
+
+	// Verify files that should still exist
+	for _, name := range []string{
+		"recent_export.zip",
+		"normal.txt",
+		"data.json",
+		"data/file.txt",
+		"data/subfolder/file.txt",
+	} {
+		_, err := os.Stat(filepath.Join(exportDir, name))
+		require.NoError(t, err, "Expected file/directory to exist: %s", name)
+	}
+
+	// Verify files that should be deleted
+	for _, name := range []string{
+		"old_export.zip",
+		"test_export.zip",
+	} {
+		_, err := os.Stat(filepath.Join(exportDir, name))
+		require.True(t, os.IsNotExist(err), "Expected file to be deleted: %s", name)
+	}
+}