Add changelog entry, add additional test case

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- `Client.Enqueue` no longer enqueues tasks with empty typename; Error message is returned.
+
 ## [0.18.2] - 2020-07-15
 
 ### Changed

client.go

@@ -179,9 +179,6 @@ func (d processInOption) Value() interface{} { return time.Duration(d) }
 // ErrDuplicateTask error only applies to tasks enqueued with a Unique option.
 var ErrDuplicateTask = errors.New("task already exists")
 
-// ErrEmptyTypename indicates that task's typename is empty.
-var ErrEmptyTypename = errors.New("task typename cannot be empty")
-
 type option struct {
 	retry     int
 	queue     string
@@ -271,7 +268,7 @@ func (c *Client) Close() error {
 // If no ProcessAt or ProcessIn options are provided, the task will be pending immediately.
 func (c *Client) Enqueue(task *Task, opts ...Option) (*TaskInfo, error) {
 	if strings.TrimSpace(task.Type()) == "" {
-		return nil, fmt.Errorf("%w", ErrEmptyTypename)
+		return nil, fmt.Errorf("task typename cannot be empty")
 	}
 	c.mu.Lock()
 	if defaults, ok := c.opts[task.Type()]; ok {

client_test.go

@@ -590,6 +590,11 @@ func TestClientEnqueueError(t *testing.T) {
 			task: NewTask("", h.JSON(map[string]interface{}{})),
 			opts: []Option{},
 		},
+		{
+			desc: "With blank task typename",
+			task: NewTask("    ", h.JSON(map[string]interface{}{})),
+			opts: []Option{},
+		},
 	}
 
 	for _, tc := range tests {