Do not apply SuffixAutoColon when suffix is only space characters

This updates the spinner only append a colon (`:`) onto the suffix if the
suffix is set, and it contains more than space characters.

spinner.go

@@ -157,8 +157,8 @@ type Config struct {
 
 	// SuffixAutoColon configures whether the spinner adds a colon after the
 	// suffix automatically. If there is a message, a colon followed by a space
-	// is added to the suffix. Otherwise, if there is no message the colon is
-	// omitted.
+	// is added to the suffix. Otherwise, if there is no message, or the suffix
+	// is only space characters, the colon is omitted.
 	//
 	// If SpinnerAtEnd is set to true, this option is ignored.
 	SuffixAutoColon bool
@@ -845,7 +845,7 @@ func paint(w io.Writer, maxWidth int, char character, prefix, message, suffix st
 		}
 
 		if suffixAutoColon { // also implicitly !spinnerAtEnd
-			if len(suffix) > 0 && len(message) > 0 && message != "\n" {
+			if len(strings.TrimSpace(suffix)) > 0 && len(message) > 0 && message != "\n" {
 				suffix += ": "
 			}
 		}

spinner_test.go

@@ -1164,7 +1164,7 @@ func TestSpinner_paintUpdate(t *testing.T) {
 			want: "\r\033[K\rmsg ay \r\033[K\rmsg az \r\033[K\rmsg az \r\033[K\rmsg ay ",
 		},
 		{
-			name: "spinner_no_hide_cursor_auto_cursor",
+			name: "spinner_no_hide_cursor_auto_cursor_empty_suffix",
 			spinner: &Spinner{
 				buffer:          &bytes.Buffer{},
 				mu:              &sync.Mutex{},
@@ -1177,7 +1177,23 @@ func TestSpinner_paintUpdate(t *testing.T) {
 				frequency:       10,
 				suffixAutoColon: true,
 			},
-			want: "\r\033[K\ray : msg\r\033[K\raz : msg\r\033[K\raz : msg\r\033[K\ray : msg",
+			want: "\r\033[K\ray msg\r\033[K\raz msg\r\033[K\raz msg\r\033[K\ray msg",
+		},
+		{
+			name: "spinner_no_hide_cursor_auto_cursor_suffix",
+			spinner: &Spinner{
+				buffer:          &bytes.Buffer{},
+				mu:              &sync.Mutex{},
+				prefix:          "a",
+				message:         "msg",
+				suffix:          " foo",
+				maxWidth:        1,
+				colorFn:         fmt.Sprintf,
+				chars:           []character{{Value: "y", Size: 1}, {Value: "z", Size: 1}},
+				frequency:       10,
+				suffixAutoColon: true,
+			},
+			want: "\r\033[K\ray foo: msg\r\033[K\raz foo: msg\r\033[K\raz foo: msg\r\033[K\ray foo: msg",
 		},
 		{
 			name: "spinner_hide_cursor",
@@ -1304,7 +1320,7 @@ func TestSpinner_paintStop(t *testing.T) {
 			want: "\r\033[K\rstop ax \n",
 		},
 		{
-			name: "ok_auto_colon",
+			name: "ok_auto_colon_empty_suffix",
 			ok:   true,
 			spinner: &Spinner{
 				buffer:          &bytes.Buffer{},
@@ -1317,7 +1333,23 @@ func TestSpinner_paintStop(t *testing.T) {
 				stopMsg:         "stop",
 				suffixAutoColon: true,
 			},
-			want: "\r\033[K\rax : stop\n",
+			want: "\r\033[K\rax stop\n",
+		},
+		{
+			name: "ok_auto_colon_suffix",
+			ok:   true,
+			spinner: &Spinner{
+				buffer:          &bytes.Buffer{},
+				mu:              &sync.Mutex{},
+				prefix:          "a",
+				suffix:          " foo",
+				maxWidth:        1,
+				stopColorFn:     fmt.Sprintf,
+				stopChar:        character{Value: "x", Size: 1},
+				stopMsg:         "stop",
+				suffixAutoColon: true,
+			},
+			want: "\r\033[K\rax foo: stop\n",
 		},
 		{
 			name: "ok_auto_colon_no_msg",