Remove legacy `unknwon/com` package (#19298)

Follows: #19284
* The `CopyDir` is only used inside test code
* Rewrite `ToSnakeCase` with more test cases
* The `RedisCacher` only put strings into cache, here we use internal `toStr` to replace the legacy `ToStr`
* The `UniqueQueue` can use string as ID directly, no need to call `ToStr`

3 files changed, 106 insertions, 3 deletions

diff --git a/models/migrations/migrations_test.go b/models/migrations/migrations_test.go
index a17eba54e8..a1fd49a8b9 100644
--- a/models/migrations/migrations_test.go
+++ b/models/migrations/migrations_test.go
@@ -203,7 +203,7 @@ func prepareTestEnv(t *testing.T, skip int, syncModels ...interface{}) (*xorm.En
 	deferFn := PrintCurrentTest(t, ourSkip)
 	assert.NoError(t, os.RemoveAll(setting.RepoRootPath))
 
-	assert.NoError(t, util.CopyDir(path.Join(filepath.Dir(setting.AppPath), "integrations/gitea-repositories-meta"),
+	assert.NoError(t, unittest.CopyDir(path.Join(filepath.Dir(setting.AppPath), "integrations/gitea-repositories-meta"),
 		setting.RepoRootPath))
 	ownerDirs, err := os.ReadDir(setting.RepoRootPath)
 	if err != nil {
diff --git a/models/unittest/fscopy.go b/models/unittest/fscopy.go
new file mode 100644
index 0000000000..ff815e729d
--- /dev/null
+++ b/models/unittest/fscopy.go
@@ -0,0 +1,103 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package unittest
+
+import (
+	"errors"
+	"io"
+	"os"
+	"path"
+	"strings"
+
+	"code.gitea.io/gitea/modules/util"
+)
+
+// Copy copies file from source to target path.
+func Copy(src, dest string) error {
+	// Gather file information to set back later.
+	si, err := os.Lstat(src)
+	if err != nil {
+		return err
+	}
+
+	// Handle symbolic link.
+	if si.Mode()&os.ModeSymlink != 0 {
+		target, err := os.Readlink(src)
+		if err != nil {
+			return err
+		}
+		// NOTE: os.Chmod and os.Chtimes don't recognize symbolic link,
+		// which will lead "no such file or directory" error.
+		return os.Symlink(target, dest)
+	}
+
+	sr, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer sr.Close()
+
+	dw, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer dw.Close()
+
+	if _, err = io.Copy(dw, sr); err != nil {
+		return err
+	}
+
+	// Set back file information.
+	if err = os.Chtimes(dest, si.ModTime(), si.ModTime()); err != nil {
+		return err
+	}
+	return os.Chmod(dest, si.Mode())
+}
+
+// CopyDir copy files recursively from source to target directory.
+//
+// The filter accepts a function that process the path info.
+// and should return true for need to filter.
+//
+// It returns error when error occurs in underlying functions.
+func CopyDir(srcPath, destPath string, filters ...func(filePath string) bool) error {
+	// Check if target directory exists.
+	if _, err := os.Stat(destPath); !errors.Is(err, os.ErrNotExist) {
+		return errors.New("file or directory already exists: " + destPath)
+	}
+
+	err := os.MkdirAll(destPath, os.ModePerm)
+	if err != nil {
+		return err
+	}
+
+	// Gather directory info.
+	infos, err := util.StatDir(srcPath, true)
+	if err != nil {
+		return err
+	}
+
+	var filter func(filePath string) bool
+	if len(filters) > 0 {
+		filter = filters[0]
+	}
+
+	for _, info := range infos {
+		if filter != nil && filter(info) {
+			continue
+		}
+
+		curPath := path.Join(destPath, info)
+		if strings.HasSuffix(info, "/") {
+			err = os.MkdirAll(curPath, os.ModePerm)
+		} else {
+			err = Copy(path.Join(srcPath, info), curPath)
+		}
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/models/unittest/testdb.go b/models/unittest/testdb.go
index b6469fb309..b6924d4706 100644
--- a/models/unittest/testdb.go
+++ b/models/unittest/testdb.go
@@ -104,7 +104,7 @@ func MainTest(m *testing.M, pathToGiteaRoot string, fixtureFiles ...string) {
 	if err = util.RemoveAll(repoRootPath); err != nil {
 		fatalTestError("util.RemoveAll: %v\n", err)
 	}
-	if err = util.CopyDir(filepath.Join(pathToGiteaRoot, "integrations", "gitea-repositories-meta"), setting.RepoRootPath); err != nil {
+	if err = CopyDir(filepath.Join(pathToGiteaRoot, "integrations", "gitea-repositories-meta"), setting.RepoRootPath); err != nil {
 		fatalTestError("util.CopyDir: %v\n", err)
 	}
 
@@ -175,7 +175,7 @@ func PrepareTestEnv(t testing.TB) {
 	assert.NoError(t, PrepareTestDatabase())
 	assert.NoError(t, util.RemoveAll(setting.RepoRootPath))
 	metaPath := filepath.Join(giteaRoot, "integrations", "gitea-repositories-meta")
-	assert.NoError(t, util.CopyDir(metaPath, setting.RepoRootPath))
+	assert.NoError(t, CopyDir(metaPath, setting.RepoRootPath))
 
 	ownerDirs, err := os.ReadDir(setting.RepoRootPath)
 	assert.NoError(t, err)