check(t, "TestBasicOperations (5)", &buf, "ab")

		n, err = buf.Write(testBytes[2:26])
		if want := 24; err != nil || n != want {
			t.Errorf("Write: got (%d, %v), want (%d, %v)", n, err, want, nil)
		}
		check(t, "TestBasicOperations (6)", &buf, testString[0:26])

		buf.Truncate(26)
		check(t, "TestBasicOperations (7)", &buf, testString[0:26])

		buf.Truncate(20)
		check(t, "TestBasicOperations (8)", &buf, testString[0:20])