Add ShardErrors.Unwrap() support

Signed-off-by: Marco Pracucci <marco@pracucci.com>

pkg/kadm/errors.go

@@ -121,3 +121,14 @@ func (e *ShardErrors) Error() string {
 	}
 	return fmt.Sprintf("request %s has %d separate shard errors, first: %s", e.Name, len(e.Errs), e.Errs[0].Err)
 }
+
+// Unwrap returns the underlying errors.
+func (e *ShardErrors) Unwrap() []error {
+	unwrapped := make([]error, 0, len(e.Errs))
+
+	for _, shardErr := range e.Errs {
+		unwrapped = append(unwrapped, shardErr.Err)
+	}
+
+	return unwrapped
+}

pkg/kadm/errors_test.go

@@ -0,0 +1,23 @@
+package kadm
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+func TestShardErrors_Unwrap(t *testing.T) {
+	err1 := errors.New("test error 1")
+	err2 := errors.New("test error 2")
+
+	errs := &ShardErrors{Errs: []ShardError{{Err: err1}, {Err: context.Canceled}}}
+	if !errors.Is(errs, err1) {
+		t.Errorf("ShardErrors does not match error %v", err1)
+	}
+	if !errors.Is(errs, context.Canceled) {
+		t.Errorf("ShardErrors does not match error %v", context.Canceled)
+	}
+	if errors.Is(errs, err2) {
+		t.Errorf("ShardErrors matches error %v but it not expected to match it", err2)
+	}
+}