Custom Filesystems

Overview

gogenfilter uses Go’s fs.FS interface, making it easy to test without real files or to read from custom sources.

Default Behavior

By default, the filter uses os.DirFS(".") (the current working directory):

package main

import "github.com/LarsArtmann/gogenfilter/v3"

func main() {
  opts, err := gogenfilter.WithFilterOptions(gogenfilter.FilterAll)
  if err != nil {
    panic(err)
  }
  f, err := gogenfilter.NewFilter(opts)
  if err != nil {
    panic(err)
  }
  // Uses os.DirFS(".") internally
  _ = f
}

Testing with MapFS

Use fstest.MapFS for deterministic, isolated tests:

package main

import (
  "testing/fstest"

  "github.com/LarsArtmann/gogenfilter/v3"
)

func main() {
  mapFS := fstest.MapFS{
    "db/models.go": &fstest.MapFile{
      Data: []byte("// Code generated by sqlc. DO NOT EDIT.\npackage db\n"),
    },
    "main.go": &fstest.MapFile{
      Data: []byte("package main\n"),
    },
  }

  opts, err := gogenfilter.WithFilterOptions(gogenfilter.FilterSQLC)
  if err != nil {
    panic(err)
  }
  fsConfig := gogenfilter.WithFS(mapFS)
  f, err := gogenfilter.NewFilter(opts, fsConfig)
  if err != nil {
    panic(err)
  }

  filtered, _ := f.Filter("db/models.go") // true
  filtered, _ = f.Filter("main.go")       // false
  _ = filtered
}

Custom Filesystem

Implement fs.FS for any source — embedded files, archives, remote storage:

package main

import (
  "embed"

  "github.com/LarsArtmann/gogenfilter/v3"
)

//go:embed testdata/*
var testdata embed.FS

func main() {
  opts, err := gogenfilter.WithFilterOptions(gogenfilter.FilterAll)
  if err != nil {
    panic(err)
  }
  f, err := gogenfilter.NewFilter(opts, gogenfilter.WithFS(testdata))
  if err != nil {
    panic(err)
  }
  _ = f
}

nil Handling

Passing nil to WithFS is safe — the filter falls back to os.DirFS(".").