Fix pointer references in ctxlog

Signed-off-by: Carlos Martín <carlos.martin.sanchez@gmail.com>

Author: carlosms

util/ctxlog/context.go

@@ -25,10 +25,17 @@ func Get(ctx context.Context) log.Logger {
 	return NewLogger(fields)
 }
 
-// Fields returns the context log fields. It can be nil
+// Fields returns a copy of the context log fields. It can be nil
 func Fields(ctx context.Context) log.Fields {
 	if v := ctx.Value(logFieldsKey); v != nil {
-		return v.(log.Fields)
+		f := v.(log.Fields)
+		copy := make(map[string]interface{}, len(f))
+
+		for key, val := range f {
+			copy[key] = val
+		}
+
+		return copy
 	}
 
 	return nil
@@ -41,16 +48,16 @@ func WithLogFields(ctx context.Context, fields log.Fields) (context.Context, log
 		return ctx, Get(ctx)
 	}
 
-	var newFields log.Fields
+	newFields := make(map[string]interface{}, len(fields))
 
 	if v := ctx.Value(logFieldsKey); v != nil {
-		newFields = v.(log.Fields)
-
-		for k, v := range fields {
-			newFields[k] = v
+		for key, val := range v.(log.Fields) {
+			newFields[key] = val
 		}
-	} else {
-		newFields = fields
+	}
+
+	for key, val := range fields {
+		newFields[key] = val
 	}
 
 	ctx = set(ctx, newFields)

util/ctxlog/context_test.go

@@ -0,0 +1,93 @@
+package ctxlog_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	log "gopkg.in/src-d/go-log.v1"
+
+	"github.com/src-d/lookout/util/ctxlog"
+)
+
+func TestEmptyGet(t *testing.T) {
+	ctx := context.Background()
+
+	log := ctxlog.Get(ctx)
+
+	require.NotNil(t, log)
+
+	require.NotPanics(t, func() {
+		log.Debugf("a test log msg")
+	})
+}
+
+func TestNilFields(t *testing.T) {
+	ctx := context.Background()
+
+	fields := ctxlog.Fields(ctx)
+
+	require.Nil(t, fields)
+}
+
+func TestWithLogFields(t *testing.T) {
+	ctxA := context.Background()
+	ctxAB, _ := ctxlog.WithLogFields(ctxA, log.Fields{"keyB": "valB"})
+	ctxABC, _ := ctxlog.WithLogFields(ctxAB, log.Fields{"keyC": "valC"})
+	ctxABD, _ := ctxlog.WithLogFields(ctxAB, log.Fields{"keyD": "valD"})
+
+	fieldsA := ctxlog.Fields(ctxA)
+	fieldsB := ctxlog.Fields(ctxAB)
+	fieldsC := ctxlog.Fields(ctxABC)
+	fieldsD := ctxlog.Fields(ctxABD)
+
+	require.NotEqual(t, fieldsA, fieldsB)
+	require.NotEqual(t, fieldsB, fieldsC)
+
+	require.Nil(t, fieldsA["keyB"])
+	require.Nil(t, fieldsA["keyC"])
+	require.Nil(t, fieldsA["keyD"])
+
+	require.Equal(t, "valB", fieldsB["keyB"])
+	require.Nil(t, fieldsB["keyC"])
+	require.Nil(t, fieldsB["keyD"])
+
+	require.Equal(t, "valB", fieldsC["keyB"])
+	require.Equal(t, "valC", fieldsC["keyC"])
+	require.Nil(t, fieldsC["keyD"])
+
+	require.Equal(t, "valB", fieldsD["keyB"])
+	require.Nil(t, fieldsD["keyC"])
+	require.Equal(t, "valD", fieldsD["keyD"])
+}
+
+func TestWithNilLogFields(t *testing.T) {
+	ctxA := context.Background()
+
+	ctxB, logger := ctxlog.WithLogFields(ctxA, nil)
+
+	require.NotNil(t, ctxB)
+	require.NotNil(t, logger)
+}
+
+func TestReadOnlyWithLogFields(t *testing.T) {
+	ctxA := context.Background()
+	ctxB, _ := ctxlog.WithLogFields(ctxA, log.Fields{"keyB": "valB"})
+
+	fieldsA := ctxlog.Fields(ctxA)
+	fieldsB := ctxlog.Fields(ctxB)
+
+	require.Nil(t, fieldsA["keyB"])
+	require.Equal(t, "valB", fieldsB["keyB"])
+
+	fieldsB["keyY"] = "valY"
+
+	fieldsA2 := ctxlog.Fields(ctxA)
+	fieldsB2 := ctxlog.Fields(ctxB)
+
+	require.Nil(t, fieldsA2["keyB"])
+	require.Nil(t, fieldsA2["keyY"])
+
+	require.Equal(t, "valB", fieldsB2["keyB"])
+	require.Nil(t, fieldsB2["keyY"])
+}