added test to validate expected behavior

pipeline/error_test.go

@@ -0,0 +1,32 @@
+package pipeline
+
+import (
+	"testing"
+
+	"github.com/pkg/errors"
+)
+
+func TestErrorWithCause(t *testing.T) {
+	rootErr := errors.New("root cause error")
+	pipeErr := NewError(rootErr, "pipeline wrapper error")
+	wrapErr := errors.Wrap(pipeErr, "wrap with stack trace")
+	causeErr := errors.Cause(wrapErr)
+	if causeErr == nil {
+		t.Fatal("cause error should not be nil")
+	}
+	if causeErr != rootErr {
+		t.Fatal("cause error should be the same as root error")
+	}
+}
+
+func TestErrorWithoutCause(t *testing.T) {
+	pipeErr := NewError(nil, "pipeline error without cause")
+	wrapErr := errors.Wrap(pipeErr, "wrap with stack trace")
+	causeErr := errors.Cause(wrapErr)
+	if causeErr == nil {
+		t.Fatal("cause error should not be nil")
+	}
+	if causeErr != pipeErr {
+		t.Fatal("cause error should be the same as pipeline error")
+	}
+}