Added Test Case Coverage for PKG/PROMISE

Signed-off-by: Naveed Jamil <naveed.jamil@tenpearls.com>

pkg/promise/promise_test.go

@@ -0,0 +1,25 @@
+package promise
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGo(t *testing.T) {
+	errCh := Go(functionWithError)
+	er := <-errCh
+	require.EqualValues(t, "Error Occurred", er.Error())
+
+	noErrCh := Go(functionWithNoError)
+	er = <-noErrCh
+	require.Nil(t, er)
+}
+
+func functionWithError() (err error) {
+	return errors.New("Error Occurred")
+}
+func functionWithNoError() (err error) {
+	return nil
+}