repl: Make full logging optional in tests

Logs will be hidden unless verbose mode is enabled on the test run.

repl/session_test.go

@@ -1,16 +1,35 @@
 package repl
 
 import (
+	"flag"
+	"io/ioutil"
+	"log"
+	"os"
 	"strings"
 	"testing"
 
 	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/configs"
+	"github.com/hashicorp/terraform/helper/logging"
 	"github.com/hashicorp/terraform/providers"
 	"github.com/hashicorp/terraform/states"
 	"github.com/hashicorp/terraform/terraform"
 )
 
+func TestMain(m *testing.M) {
+	flag.Parse()
+
+	if testing.Verbose() {
+		// if we're verbose, use the logging requested by TF_LOG
+		logging.SetOutput()
+	} else {
+		// otherwise silence all logs
+		log.SetOutput(ioutil.Discard)
+	}
+
+	os.Exit(m.Run())
+}
+
 func TestSession_basicState(t *testing.T) {
 	state := states.BuildState(func(s *states.SyncState) {
 		s.SetResourceInstanceCurrent(