if got := string(ss.Suffix()); got != "abc" {
		t.Errorf("got = %q; want abc", got)
	}
	ss.Write([]byte("defghijklmno"))
	if got := string(ss.Suffix()); got != "fghijklmno" {
		t.Errorf("got = %q; want fghijklmno", got)
	}
	if got, want := ss.Size(), int64(len("abc")+len("defghijklmno")); got != want {
		t.Errorf("Size = %d; want %d", got, want)
	}
	buf := make([]byte, ss.Size())

    assertThat(source!!.read(sourceBuffer, 5)).isEqualTo(5)
    assertThat(sourceBuffer.readUtf8()).isEqualTo("abcde")
    assertThat(source.read(sourceBuffer, 1024)).isEqualTo(8)
    assertThat(sourceBuffer.readUtf8()).isEqualTo("fghijklm")
    assertThat(source.read(sourceBuffer, 1024)).isEqualTo(-1)
    assertThat(sourceBuffer.size).isEqualTo(0)
    source.close()
    assertThat(relay.isClosed).isTrue()

	}
	if s, err := buf.Peek(4); string(s) != "ghij" || err != nil {
		t.Fatalf("want %q got %q, err=%v", "ghij", string(s), err)
	}
	if _, err := buf.Read(p[0:]); string(p[0:]) != "ghijklmnop" || err != nil {
		t.Fatalf("want %q got %q, err=%v", "ghijklmnop", string(p[0:minReadBufferSize]), err)
	}
	if s, err := buf.Peek(0); string(s) != "" || err != nil {
		t.Fatalf("want %q got %q, err=%v", "", string(s), err)
	}