grpc/config/file/config_test.go

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// inspired by / taken from github.com/spf13/viper
package file
import (
"context"
"os"
"os/exec"
"path"
"path/filepath"
"runtime"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"go.linka.cloud/grpc/config"
)
func newConfigFile(t *testing.T) (config.Config, string, func()) {
path := filepath.Join(os.TempDir(), "config.yaml")
if err := os.WriteFile(path, []byte("ok"), os.ModePerm); err != nil {
t.Fatal(err)
}
cleanUp := func() {
if err := os.Remove(path); err != nil {
t.Error(err)
}
}
return &file{path: path}, path, cleanUp
}
func newSymlinkedConfigFile(t *testing.T) (config.Config, string, string, func()) {
watchDir, err := os.MkdirTemp("", "")
require.Nil(t, err)
dataDir1 := path.Join(watchDir, "data1")
err = os.Mkdir(dataDir1, 0o777)
require.Nil(t, err)
realConfigFile := path.Join(dataDir1, "config.yaml")
t.Logf("Real config file location: %s\n", realConfigFile)
err = os.WriteFile(realConfigFile, []byte("foo: bar\n"), 0o640)
require.Nil(t, err)
cleanup := func() {
os.RemoveAll(watchDir)
}
// now, symlink the tm `data1` dir to `data` in the baseDir
os.Symlink(dataDir1, path.Join(watchDir, "data"))
// and link the `<watchdir>/datadir1/config.yaml` to `<watchdir>/config.yaml`
configFile := path.Join(watchDir, "config.yaml")
os.Symlink(path.Join(watchDir, "data", "config.yaml"), configFile)
path := path.Join(watchDir, "config.yaml")
t.Logf("Config file location: %s\n", path)
return &file{path: path}, watchDir, configFile, cleanup
}
func TestWatch(t *testing.T) {
t.Run("file content changed", func(t *testing.T) {
// given a `config.yaml` file being watched
v, cpath, cleanup := newConfigFile(t)
defer cleanup()
updates := make(chan []byte, 1)
if err := v.Watch(context.Background(), updates); err != nil {
t.Fatal(err)
}
// when overwriting the file and waiting for the custom change notification handler to be triggered
err := os.WriteFile(cpath, []byte("foo: baz\n"), 0o640)
b := <-updates
// then the config value should have changed
require.Nil(t, err)
assert.Equal(t, []byte("foo: baz\n"), b)
})
t.Run("link to real file changed (à la Kubernetes)", func(t *testing.T) {
// skip if not executed on Linux
if runtime.GOOS != "linux" {
t.Skipf("Skipping test as symlink replacements don't work on non-linux environment...")
}
v, watchDir, _, cleanup := newSymlinkedConfigFile(t)
defer cleanup()
updates := make(chan []byte, 1)
if err := v.Watch(context.Background(), updates); err != nil {
t.Fatal(err)
}
// when link to another `config.yaml` file
dataDir2 := path.Join(watchDir, "data2")
err := os.MkdirAll(dataDir2, 0o777)
require.NoError(t, err)
configFile2 := path.Join(dataDir2, "config.yaml")
err = os.WriteFile(configFile2, []byte("foo: baz\n"), 0o640)
require.NoError(t, err)
// change the symlink using the `ln -sfn` command
err = exec.Command("ln", "-sfn", dataDir2, path.Join(watchDir, "data")).Run()
require.NoError(t, err)
b := <-updates
assert.Equal(t, []byte("foo: baz\n"), b)
})
}