Merge pull request #902 from sryoya/add_condition_to_the_validation_f…

…unction_for_TextBlockObject

Add the new condition to the validation func for TextBlockObject

block_object.go

@@ -138,6 +138,10 @@ func (s TextBlockObject) MixedElementType() MixedElementType {
 
 // Validate checks if TextBlockObject has valid values
 func (s TextBlockObject) Validate() error {
+	if s.Type != "plain_text" && s.Type != "mrkdwn" {
+		return errors.New("type must be either of plain_text or mrkdwn")
+	}
+
 	// https://github.com/slack-go/slack/issues/881
 	if s.Type == "mrkdwn" && s.Emoji {
 		return errors.New("emoji cannot be true in mrkdown")

block_object_test.go

@@ -99,6 +99,24 @@ func TestValidateTextBlockObject(t *testing.T) {
 			},
 			expected: nil,
 		},
+		{
+			input: TextBlockObject{
+				Type:     "mrkdwn",
+				Text:     "testText",
+				Emoji:    false,
+				Verbatim: false,
+			},
+			expected: nil,
+		},
+		{
+			input: TextBlockObject{
+				Type:     "invalid",
+				Text:     "testText",
+				Emoji:    false,
+				Verbatim: false,
+			},
+			expected: errors.New("type must be either of plain_text or mrkdwn"),
+		},
 		{
 			input: TextBlockObject{
 				Type:     "mrkdwn",