stream/mts/meta_test.go: added TestGetAbsent key to check that we get an error when we try and get data with key that doesn't exist in metadata map

stream/mts/meta.go

@@ -32,6 +32,10 @@ import (
 	"sync"
 )
 
+var (
+	errKeyAbsent = errors.New("Key does not exist in map")
+)
+
 type Meta struct {
 	mu   sync.RWMutex
 	data map[string]string
@@ -51,7 +55,7 @@ func (m *Meta) Add(key, val string) {
 // All returns the a copy of the map containing the meta data
 func (m *Meta) All() map[string]string {
 	m.mu.Lock()
-	var cpy map[string]string
+	cpy := make(map[string]string)
 	for k, v := range m.data {
 		cpy[k] = v
 	}
@@ -65,7 +69,7 @@ func (m *Meta) Get(key string) (string, error) {
 	val, ok := m.data[key]
 	m.mu.Unlock()
 	if !ok {
-		return "", errors.New("Key does not exist in metadata map")
+		return "", errKeyAbsent
 	}
 
 	return val, nil

stream/mts/meta_test.go

@@ -83,8 +83,14 @@ func TestAll(t *testing.T) {
 	}
 }
 
-// TODO: test all
-// TODO: test get when key exists
 // TODO: test get when key doesn't exist
+func TestGetAbsentKey(t *testing.T) {
+	meta := NewMeta()
+
+	if _, err := meta.Get("loc"); err != errKeyAbsent {
+		t.Errorf("Expected error: %v", errKeyAbsent.Error())
+	}
+}
+
 // TODO: test delete when key exists
 // TODO: test delete when key doesn't exist