1 files changed, 36 insertions, 0 deletions
diff --git a/src/io/fs/stat_test.go b/src/io/fs/stat_test.go
new file mode 100644
index 0000000000..e312b6fbd9
--- /dev/null
+++ b/src/io/fs/stat_test.go
@@ -0,0 +1,36 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fs_test
+
+import (
+	"fmt"
+	. "io/fs"
+	"testing"
+)
+
+type statOnly struct{ StatFS }
+
+func (statOnly) Open(name string) (File, error) { return nil, ErrNotExist }
+
+func TestStat(t *testing.T) {
+	check := func(desc string, info FileInfo, err error) {
+		t.Helper()
+		if err != nil || info == nil || info.Mode() != 0456 {
+			infoStr := "<nil>"
+			if info != nil {
+				infoStr = fmt.Sprintf("FileInfo(Mode: %#o)", info.Mode())
+			}
+			t.Fatalf("Stat(%s) = %v, %v, want Mode:0456, nil", desc, infoStr, err)
+		}
+	}
+
+	// Test that Stat uses the method when present.
+	info, err := Stat(statOnly{testFsys}, "hello.txt")
+	check("statOnly", info, err)
+
+	// Test that Stat uses Open when the method is not present.
+	info, err = Stat(openOnly{testFsys}, "hello.txt")
+	check("openOnly", info, err)
+}