add test for spinner

Signed-off-by: Billy Zha <[email protected]>

cmd/oras/internal/display/progress/spinner_test.go

@@ -0,0 +1,30 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package progress
+
+import "testing"
+
+func Test_spinner_symbol(t *testing.T) {
+	var s spinner
+	for i := 0; i < len(spinnerSymbols); i++ {
+		if s.symbol() != spinnerSymbols[i] {
+			t.Errorf("symbol() = %v, want %v", s.symbol(), spinnerSymbols[i])
+		}
+	}
+	if s.symbol() != spinnerSymbols[0] {
+		t.Errorf("symbol() = %v, want %v", s.symbol(), spinnerSymbols[0])
+	}
+}