enable logger.With().Context(ctx).Logger() pattern (#7)

* enable logger.With().Context(ctx).Logger() pattern

* fix failing tests

* fix more failing tests

binary_test.go

@@ -5,6 +5,7 @@ package zerolog
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 

context.go

@@ -19,6 +19,12 @@ func (c Context) Logger() Logger {
 	return c.l
 }
 
+// Context adds the context.Context to the logger ctx.
+func (c Context) Context(ctx context.Context) Context {
+	c.l.ctx = ctx
+	return c
+}
+
 // Fields is a helper function to use a map or slice to set fields using type assertion.
 // Only map[string]interface{} and []interface{} are accepted. []interface{} must
 // alternate string keys and arbitrary values, and extraneous ones are ignored.

hook_test.go

@@ -2,33 +2,34 @@ package zerolog
 
 import (
 	"bytes"
+	"context"
 	"io/ioutil"
 	"testing"
 )
 
 var (
-	levelNameHook = HookFunc(func(e *Event, level Level, msg string) {
+	levelNameHook = HookFunc(func(ctx context.Context, e *Event, level Level, msg string) {
 		levelName := level.String()
 		if level == NoLevel {
 			levelName = "nolevel"
 		}
 		e.Str("level_name", levelName)
 	})
-	simpleHook = HookFunc(func(e *Event, level Level, msg string) {
+	simpleHook = HookFunc(func(ctx context.Context, e *Event, level Level, msg string) {
 		e.Bool("has_level", level != NoLevel)
 		e.Str("test", "logged")
 	})
-	copyHook = HookFunc(func(e *Event, level Level, msg string) {
+	copyHook = HookFunc(func(ctx context.Context, e *Event, level Level, msg string) {
 		hasLevel := level != NoLevel
 		e.Bool("copy_has_level", hasLevel)
 		if hasLevel {
 			e.Str("copy_level", level.String())
 		}
 		e.Str("copy_msg", msg)
 	})
-	nopHook = HookFunc(func(e *Event, level Level, message string) {
+	nopHook = HookFunc(func(ctx context.Context, e *Event, level Level, message string) {
 	})
-	discardHook = HookFunc(func(e *Event, level Level, message string) {
+	discardHook = HookFunc(func(ctx context.Context, e *Event, level Level, message string) {
 		e.Discard()
 	})
 )

log.go

@@ -100,6 +100,7 @@ package zerolog
 
 import (
 	"errors"
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -216,6 +217,7 @@ type Logger struct {
 	level   Level
 	sampler Sampler
 	context []byte
+	ctx     context.Context
 	hooks   []Hook
 	stack   bool
 }
@@ -459,6 +461,9 @@ func (l *Logger) newEvent(level Level, done func(string)) *Event {
 	if l.context != nil && len(l.context) > 1 {
 		e.buf = enc.AppendObjectData(e.buf, l.context)
 	}
+	if l.ctx != nil {
+		e.ctx = l.ctx
+	}
 	if l.stack {
 		e.Stack()
 	}