cyberark/secretless-broker

package configfile

import (
    "io/ioutil"
    "os"
    "testing"
    "time"

    "github.com/stretchr/testify/assert"
)

func TestAttachWatcher(t *testing.T) {
    t.Run("AttachWatcher", func(t *testing.T) {
        // Mock the log.Fatal function to intercept fatal errors for inspection
        var watcherErr error
        logFatal = func(v ...interface{}) {
            watcherErr = v[0].(error)
        }
        // Create a listener that will track the number of times the watcher detects a file change
        changeCount := 0
        // Allow a 10ms delay for the watcher to detect the file change
        delay := time.Millisecond * 10
        onChange := func() {
            changeCount++
        }

        checkChangeCount := func(t *testing.T, expectedValue int) {
            // Wait the specified amount, the assert that the change count is as expected
            time.Sleep(delay)
            assert.Equal(t, expectedValue, changeCount)
        }

        // Create a temp file to watch
        tempDir, _ := ioutil.TempDir("", "configfile_watcher")
        defer os.RemoveAll(tempDir)
        file, err := os.CreateTemp(tempDir, "configfile")
        assert.NoError(t, err)

        AttachWatcher(file.Name(), onChange)
        checkChangeCount(t, 0)
        assert.NoError(t, watcherErr)

        // Write to the file and check that the listener is called
        _, err = file.WriteString("test")
        assert.NoError(t, err)
        checkChangeCount(t, 1)
        assert.NoError(t, watcherErr)

        _, err = file.WriteString("test again")
        file.Close()
        assert.NoError(t, err)
        checkChangeCount(t, 2)
        assert.NoError(t, watcherErr)

        // Delete the file and check that the listener is called and an error occurs
        err = os.Remove(file.Name())
        assert.NoError(t, err)
        // Wait longer because the watcher tries to reattach to deleted files in case they're recreated
        time.Sleep(1 * time.Second)
        checkChangeCount(t, 3)
        assert.Error(t, watcherErr)
    })
}