support prefix for default router

default_writing_router.go

@@ -12,10 +12,45 @@ import (
 )
 
 
-// DefaultWritingRouter returns an initialized DefaultWritingRouter
+// NewDefaultWritingRouter returns an initialized DefaultWritingRouter
 func NewDefaultWritingRouter(writer io.Writer) *DefaultWritingRouter {
+	return NewDefaultWritingRouterWithPrefix(writer, nil)
+}
+
+// NewDefaultWritingRouterWithPrefix returns an initialized DefaultWritingRouter
+func NewDefaultWritingRouterWithPrefix(writer io.Writer, prefix map[string]interface{}) *DefaultWritingRouter {
+	var prefixBuffer []byte
+	if 0 < len(prefix) {
+//@TODO: This is a potential heavy operation. Is there a better way
+//       to get the ultimate result this is trying to archive?
+//
+		sortedKeys := make([]string, len(prefix))
+		i := 0
+		for key, _ := range prefix {
+			sortedKeys[i] = key
+			i++
+		}
+		sort.Strings(sortedKeys)
+
+		for _, key := range sortedKeys {
+
+			value := prefix[key]
+
+			if s, ok := value.(string); !ok {
+				prefixBuffer = dotquote.AppendString(prefixBuffer, fmt.Sprintf("%T", value), key, "type")
+				prefixBuffer = append(prefixBuffer, ' ')
+				prefixBuffer = dotquote.AppendString(prefixBuffer, fmt.Sprintf("%v", value), key, "value")
+				prefixBuffer = append(prefixBuffer, ' ')
+			} else {
+				prefixBuffer = dotquote.AppendString(prefixBuffer, s, key)
+				prefixBuffer = append(prefixBuffer, ' ')
+			}
+		}
+	}
+
 	router := DefaultWritingRouter{
 		writer:writer,
+		prefix:prefixBuffer,
 	}
 
 	return &router
@@ -28,6 +63,7 @@ func NewDefaultWritingRouter(writer io.Writer) *DefaultWritingRouter {
 // deployment enviornment.
 type DefaultWritingRouter struct {
 	writer io.Writer
+	prefix []byte
 }
 
 
@@ -48,6 +84,10 @@ func (router *DefaultWritingRouter) Route(message string, context map[string]int
 	var buffer [512]byte
 	p := buffer[:0]
 
+	if prefix := router.prefix; 0 < len(prefix) {
+		p = append(p, prefix...)
+	}
+
 
 	p = dotquote.AppendString(p, message, "text")
 	p = append(p, ' ')

default_writing_router_test.go

@@ -64,3 +64,65 @@ func TestDefaultWritingRouterRoute(t *testing.T) {
 		}
 	}
 }
+
+
+func TestDefaultWritingRouterWithPrefixRoute(t *testing.T) {
+
+	tests := []struct{
+		Message string
+		Context map[string]interface{}
+		Prefix map[string]interface{}
+		ExpectContains []string
+	}{
+		{
+			Message: "Hello world!",
+			Context: map[string]interface{}{
+				"apple": "one",
+				"banana": 2,
+				"cherry": 3.3,
+				"kiwi":   true,
+				"~error": errors.New("test error"),
+			},
+			Prefix: map[string]interface{}{
+				"name": "backendapi",
+				"number": "123",
+			},
+			ExpectContains: []string{
+				`"name"="backendapi" "number"="123"`,
+				`"text"="Hello world!"`,
+				` "ctx"."apple"."type"="string" "ctx"."apple"."value"="one" "ctx"."banana"."type"="int" "ctx"."banana"."value"="2" "ctx"."cherry"."type"="float64" "ctx"."cherry"."value"="3.3" "ctx"."kiwi"."type"="bool" "ctx"."kiwi"."value"="true"`,
+				` "error"."type"="*errors.errorString" "error"."text"="test error" `,
+				` "when"="`,
+			},
+		},
+	}
+
+
+	for testNumber, test := range tests {
+
+		var buffer bytes.Buffer
+
+		var router Router = NewDefaultWritingRouterWithPrefix(&buffer, test.Prefix)
+
+		ctx := map[string]interface{}{}
+		for n, v := range test.Context {
+			ctx[n] = v
+		}
+
+		if err := router.Route(test.Message, ctx); nil != err {
+			t.Errorf("For test #%d, did not expect an error, but actually got one: (%T) %v", testNumber, err, err)
+			continue
+		}
+
+		{
+			actual := buffer.String()
+			for expectedNumber, expectContains := range test.ExpectContains {
+
+				if !strings.Contains(actual, expectContains) {
+					t.Errorf("For test #%d and expected #%d, expect to contain, actual:\n==)>%s<(==\n==)>%s<(==", testNumber, expectedNumber, expectContains, actual)
+					continue
+				}
+			}
+		}
+	}
+}