Add context methods

ctx.go

@@ -0,0 +1,16 @@
+package zerolog
+
+import "context"
+
+type ctxKey struct{}
+
+// WithContext returns a copy of ctx with l associated.
+func (l Logger) WithContext(ctx context.Context) context.Context {
+	return context.WithValue(ctx, ctxKey{}, l)
+}
+
+// FromContext returns the Logger associated with the ctx.
+func FromContext(ctx context.Context) (l Logger, ok bool) {
+	l, ok = ctx.Value(ctxKey{}).(Logger)
+	return
+}

ctx_test.go

@@ -0,0 +1,28 @@
+package zerolog
+
+import (
+	"context"
+	"io/ioutil"
+	"reflect"
+	"testing"
+)
+
+func TestCtx(t *testing.T) {
+	log := New(ioutil.Discard)
+	ctx := log.WithContext(context.Background())
+	log2, ok := FromContext(ctx)
+	if !ok {
+		t.Error("Expected ok=true from FromContext")
+	}
+	if !reflect.DeepEqual(log, log2) {
+		t.Error("FromContext did not return the expected logger")
+	}
+
+	log2, ok = FromContext(context.Background())
+	if ok {
+		t.Error("Expected ok=false from FromContext")
+	}
+	if !reflect.DeepEqual(log2, Logger{}) {
+		t.Error("FromContext did not return the expected logger")
+	}
+}