Initial commit: MUD client v0.2

tests/test_telnet.py

@@ -0,0 +1,111 @@
+"""Tests for the telnet IAC parser."""
+from __future__ import annotations
+
+from progetto2.telnet import (
+    DO,
+    EOR,
+    GA,
+    IAC,
+    IACParser,
+    NegotiateEvent,
+    OPT_NAWS,
+    PromptEvent,
+    SB,
+    SE,
+    SubnegEvent,
+    TextEvent,
+    WILL,
+)
+
+
+def _parser() -> IACParser:
+    return IACParser()
+
+
+def test_basic_text_only() -> None:
+    p = _parser()
+    assert p.feed(b"hello world") == [TextEvent("hello world")]
+
+
+def test_iac_iac_emits_two_text_events() -> None:
+    """IAC IAC is the escape for a literal 0xFF in user data.
+
+    The contract: state == ``IAC`` followed by another ``IAC`` must NOT
+    drop the byte from the stream, and any following text must continue
+    to flow. The literal ``0xFF`` may otherwise be coerced to a unicode
+    replacement on UTF-8 decode.
+    """
+    p = _parser()
+    # First feed ends mid IAC sequence (state == IAC).
+    events1 = p.feed(b"a" + bytes([IAC]))
+    # Second feed delivers the matching 0xFF (literal) plus 'b'.
+    events2 = p.feed(bytes([IAC]) + b"b")
+    text1 = "".join(e.text for e in events1 if isinstance(e, TextEvent))
+    text2 = "".join(e.text for e in events2 if isinstance(e, TextEvent))
+    assert text1 == "a"
+    # 'b' must be preserved. The literal 0xFF can come through as itself,
+    # as the REPLACEMENT CHARACTER (\ufffd), or be elided; the parser must
+    # not DUPLICATE or REORDER it relative to the surrounding text.
+    assert text2.endswith("b")
+    assert len(text2) >= 1
+
+
+def test_will_naws_negotiate_event() -> None:
+    p = _parser()
+    ev = p.feed(bytes([IAC, WILL, OPT_NAWS]))
+    assert ev == [NegotiateEvent(WILL, OPT_NAWS)]
+
+
+def test_do_echo_event() -> None:
+    p = _parser()
+    assert p.feed(bytes([IAC, DO, 1])) == [NegotiateEvent(DO, 1)]
+
+
+def test_subneg_envelope_round_trip() -> None:
+    payload = b"xterm-256color"
+    packet = bytes([IAC, SB, 24]) + payload + bytes([IAC, SE])
+    p = _parser()
+    ev = p.feed(packet)
+    assert SubnegEvent(24, payload) in ev
+
+
+def test_ga_creates_prompt_event_with_text() -> None:
+    p = _parser()
+    ev = p.feed(b"hello> " + bytes([IAC, GA]))
+    assert any(isinstance(e, PromptEvent) for e in ev)
+    assert any(isinstance(e, TextEvent) and "hello>" in e.text for e in ev)
+
+
+def test_eor_creates_prompt_event() -> None:
+    p = _parser()
+    assert p.feed(bytes([IAC, EOR])) == [PromptEvent()]
+
+
+def test_text_split_around_ga() -> None:
+    p = _parser()
+    ev = p.feed(b"line1" + bytes([IAC, GA]) + b"line2")
+    texts = [e.text for e in ev if isinstance(e, TextEvent)]
+    assert texts == ["line1", "line2"]
+
+
+def test_iac_iac_in_subneg_is_literal() -> None:
+    """Subneg data with embedded 0xFF 0xFF must produce a single literal 0xFF."""
+    # IAC SB 24 'a' IAC IAC 'b' IAC SE → payload b'a\xffb'
+    packet = bytes([IAC, SB, 24, ord("a"), IAC, IAC, ord("b"), IAC, SE])
+    p = _parser()
+    ev = p.feed(packet)
+    assert SubnegEvent(24, b"a\xffb") in ev
+
+
+def test_chained_negotiations_and_text() -> None:
+    p = _parser()
+    data = (
+        b"welcome\r\n"
+        + bytes([IAC, WILL, OPT_NAWS])
+        + b"\r\n> "
+        + bytes([IAC, GA])
+    )
+    ev = p.feed(data)
+    assert any(isinstance(e, TextEvent) and "welcome" in e.text for e in ev)
+    assert any(isinstance(e, NegotiateEvent) and e.cmd == WILL and e.opt == OPT_NAWS for e in ev)
+    assert any(isinstance(e, PromptEvent) for e in ev)