lib: Use counterfeiter to mock interfaces in tests (#7375)

script/prune_mocks.go

@@ -0,0 +1,79 @@
+// Copyright (C) 2021 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// +build ignore
+
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+func main() {
+	var path string
+	flag.StringVar(&path, "t", "", "Name of file to prune")
+	flag.Parse()
+
+	filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			log.Fatal(err)
+		}
+		if !info.Mode().IsRegular() {
+			return nil
+		}
+		err = pruneInterfaceCheck(path, info.Size())
+		if err != nil {
+			log.Fatal(err)
+		}
+		err = exec.Command("goimports", "-w", path).Run()
+		if err != nil {
+			log.Fatal(err)
+		}
+		return nil
+	})
+}
+
+func pruneInterfaceCheck(path string, size int64) error {
+	fd, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+
+	tmp, err := ioutil.TempFile(".", "")
+	if err != nil {
+		return err
+	}
+
+	scanner := bufio.NewScanner(fd)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(strings.TrimSpace(line), "var _ ") {
+			continue
+		}
+		if _, err := tmp.WriteString(line + "\n"); err != nil {
+			os.Remove(tmp.Name())
+			return err
+		}
+	}
+
+	if err := fd.Close(); err != nil {
+		return err
+	}
+	if err := os.Remove(path); err != nil {
+		return err
+	}
+	return os.Rename(tmp.Name(), path)
+}