tw.check(t, "abc12345", "6789012345") // use Write and then WriteString since the remaining part is still longer than BufSize
	}
	{
		tw := &teststringwriter{}
		b := NewWriterSize(tw, BufSize)
		b.Write([]byte("abc")) // same as above, but use Write instead of WriteString
		tw.check(t, "", "")
		b.WriteString("123456789012345")
		tw.check(t, "abc12345", "6789012345") // same as above
	}
}

type StringTest struct {
	in  string
	out []byte
}

var upperTests = []StringTest{
	{"", []byte("")},
	{"ONLYUPPER", []byte("ONLYUPPER")},
	{"abc", []byte("ABC")},
	{"AbC123", []byte("ABC123")},
	{"azAZ09_", []byte("AZAZ09_")},
	{"longStrinGwitHmixofsmaLLandcAps", []byte("LONGSTRINGWITHMIXOFSMALLANDCAPS")},