refactor: make measurex depend on measurexlite (#892)

This diff makes `measurex` depend on `measurexlite` rather than the other way around.

While there, add unit tests.

Closes https://github.com/ooni/probe/issues/2240

internal/measurex/failure.go

@@ -1,12 +1,6 @@
 package measurex
 
-// NewFailure creates a serializable failure from an error. We
-// cannot round trip an error using JSON, so we serialize to this
-// intermediate format that is a sort of Optional<string>.
-func NewFailure(err error) *string {
-	if err == nil {
-		return nil
-	}
-	s := err.Error()
-	return &s
-}
+import "github.com/ooni/probe-cli/v3/internal/measurexlite"
+
+// NewFailure is an alias for  measurexlite.NewFailure
+var NewFailure = measurexlite.NewFailure

internal/measurex/logger.go

@@ -1,63 +1,15 @@
 package measurex
 
+import "github.com/ooni/probe-cli/v3/internal/measurexlite"
+
 //
 // Logger
 //
 // Code for logging
 //
 
-import (
-	"fmt"
-	"sync"
-	"time"
+// NewOperationLogger is an alias for measurex.NewOperationLogger.
+var NewOperationLogger = measurexlite.NewOperationLogger
 
-	"github.com/ooni/probe-cli/v3/internal/model"
-)
-
-// NewOperationLogger creates a new logger that logs
-// about an in-progress operation.
-func NewOperationLogger(logger model.Logger, format string, v ...interface{}) *OperationLogger {
-	ol := &OperationLogger{
-		sighup:  make(chan interface{}),
-		logger:  logger,
-		once:    &sync.Once{},
-		message: fmt.Sprintf(format, v...),
-		wg:      &sync.WaitGroup{},
-	}
-	ol.wg.Add(1)
-	go ol.logloop()
-	return ol
-}
-
-// OperationLogger logs about an in-progress operation
-type OperationLogger struct {
-	logger  model.Logger
-	message string
-	once    *sync.Once
-	sighup  chan interface{}
-	wg      *sync.WaitGroup
-}
-
-func (ol *OperationLogger) logloop() {
-	defer ol.wg.Done()
-	timer := time.NewTimer(500 * time.Millisecond)
-	defer timer.Stop()
-	select {
-	case <-timer.C:
-		ol.logger.Infof("%s... in progress", ol.message)
-	case <-ol.sighup:
-		// we'll emit directly in stop
-	}
-}
-
-func (ol *OperationLogger) Stop(err error) {
-	ol.once.Do(func() {
-		close(ol.sighup)
-		ol.wg.Wait()
-		if err != nil {
-			ol.logger.Infof("%s... %s", ol.message, err.Error())
-			return
-		}
-		ol.logger.Infof("%s... ok", ol.message)
-	})
-}
+// OperationLogger is an alias for measurex.OperationLogger.
+type OperationLogger = measurexlite.OperationLogger