1 files changed, 41 insertions, 0 deletions
diff --git a/errext/cleanup_test.go b/errext/cleanup_test.go
new file mode 100644
index 0000000..09b3173
--- /dev/null
+++ b/errext/cleanup_test.go
@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package errext_test
+
+import (
+	"errors"
+	"testing"
+
+	"go.xyrillian.de/gg/assert"
+	"go.xyrillian.de/gg/errext"
+)
+
+type fooError struct{}
+type barError struct{}
+type bazError struct{}
+
+func (fooError) Error() string { return "foo" }
+func (barError) Error() string { return "bar" }
+func (bazError) Error() string { return "baz" }
+
+func TestIOError(t *testing.T) {
+	err := errext.WithCleanup(nil, "File.Close", nil)
+	assert.Equal(t, err == nil, true)
+
+	err = errext.WithCleanup(fooError{}, "File.Close", nil)
+	assert.ErrEqual(t, err, "foo")
+	assert.Equal(t, err, error(fooError{})) // check for no wrapping in type ioError without cleanup error
+
+	err = errext.WithCleanup(nil, "File.Close", barError{})
+	assert.ErrEqual(t, err, "during File.Close(): bar")
+	assert.Equal(t, errors.Is(err, fooError{}), false)
+	assert.Equal(t, errors.Is(err, barError{}), true)
+	assert.Equal(t, errors.Is(err, bazError{}), false)
+
+	err = errext.WithCleanup(fooError{}, "File.Close", barError{})
+	assert.ErrEqual(t, err, "foo (additional error during File.Close(): bar)")
+	assert.Equal(t, errors.Is(err, fooError{}), true)
+	assert.Equal(t, errors.Is(err, barError{}), true)
+	assert.Equal(t, errors.Is(err, bazError{}), false)
+}