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https://github.com/blackboxprogramming/universal-computer.git
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Alexa Amundson
efffc8e4d6
- GitHub Actions CI: Python 3.10/3.11/3.12, pytest, smoke tests - Tests: tape representation, incrementer, even/odd, halt detection, step limits, missing transitions, stay direction - README with badges, theory section, machine creation docs Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> RoadChain-SHA2048: d4d129eaf6941a81 RoadChain-Identity: alexa@sovereign RoadChain-Full: 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
151 lines
5.1 KiB
Python
151 lines
5.1 KiB
Python
"""Tests for the Universal Turing Machine simulator."""
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import json
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import os
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import pytest
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import sys
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sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
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from utm import TuringMachine, parse_tape, tape_to_string
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MACHINES_DIR = os.path.join(os.path.dirname(__file__), '..', 'machines')
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def load_machine(name: str) -> TuringMachine:
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path = os.path.join(MACHINES_DIR, name)
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with open(path, 'r') as f:
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return TuringMachine(json.load(f))
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# ── Tape representation ────────────────────────────────────────────────────
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class TestTape:
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def test_parse_tape_basic(self):
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tape = parse_tape("1101", "_")
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assert tape == {0: "1", 1: "1", 2: "0", 3: "1"}
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def test_parse_tape_empty(self):
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tape = parse_tape("", "_")
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assert tape == {}
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def test_parse_tape_with_blanks(self):
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tape = parse_tape("1_0", "_")
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assert tape == {0: "1", 2: "0"}
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def test_tape_to_string(self):
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tape = {0: "1", 1: "1", 2: "1", 3: "0"}
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assert tape_to_string(tape, "_") == "1110"
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def test_tape_to_string_empty(self):
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assert tape_to_string({}, "_") == ""
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def test_tape_to_string_with_gaps(self):
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tape = {0: "1", 2: "1"}
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result = tape_to_string(tape, "_")
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assert result == "1_1"
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# ── Incrementer machine ────────────────────────────────────────────────────
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class TestIncrementer:
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def test_increment_unary_3(self):
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"""111 (unary 3) should become 1111 (unary 4)."""
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tm = load_machine("incrementer.json")
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tape = parse_tape("111", tm.blank)
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final_tape, steps, state = tm.run(tape)
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result = tape_to_string(final_tape, tm.blank)
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assert result == "1111"
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assert state == tm.halt
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def test_increment_unary_1(self):
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"""1 (unary 1) should become 11 (unary 2)."""
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tm = load_machine("incrementer.json")
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tape = parse_tape("1", tm.blank)
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final_tape, steps, state = tm.run(tape)
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result = tape_to_string(final_tape, tm.blank)
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assert result == "11"
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def test_increment_empty(self):
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"""Empty tape should become 1 (unary 1)."""
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tm = load_machine("incrementer.json")
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tape = parse_tape("", tm.blank)
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final_tape, steps, state = tm.run(tape)
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result = tape_to_string(final_tape, tm.blank)
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assert result == "1"
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# ── Even/odd machine ──────────────────────────────────────────────────────
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class TestEvenOdd:
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def test_even_length(self):
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tm = load_machine("even_odd.json")
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tape = parse_tape("1111", tm.blank)
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final_tape, steps, state = tm.run(tape)
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assert state == tm.halt
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def test_odd_length(self):
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tm = load_machine("even_odd.json")
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tape = parse_tape("111", tm.blank)
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final_tape, steps, state = tm.run(tape)
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assert state == tm.halt
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# ── Machine behavior ──────────────────────────────────────────────────────
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class TestMachineBehavior:
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def test_halts_within_step_limit(self):
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tm = load_machine("incrementer.json")
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tape = parse_tape("1", tm.blank)
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_, steps, _ = tm.run(tape, max_steps=100)
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assert steps < 100
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def test_step_limit_prevents_infinite_loop(self):
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"""A machine that never halts should stop at max_steps."""
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desc = {
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"states": ["q0"],
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"alphabet": ["0", "1"],
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"blank": "_",
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"transitions": {"q0:0": ["q0", "1", "R"], "q0:1": ["q0", "0", "R"], "q0:_": ["q0", "0", "R"]},
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"start": "q0",
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"halt": "halt"
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}
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tm = TuringMachine(desc)
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tape = parse_tape("0", tm.blank)
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_, steps, state = tm.run(tape, max_steps=50)
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assert steps == 50
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assert state != tm.halt
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def test_missing_transition_stops(self):
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"""Machine should stop when no transition exists."""
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desc = {
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"states": ["q0", "halt"],
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"alphabet": ["a"],
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"blank": "_",
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"transitions": {},
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"start": "q0",
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"halt": "halt"
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}
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tm = TuringMachine(desc)
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tape = parse_tape("a", tm.blank)
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_, steps, state = tm.run(tape)
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assert steps == 0
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assert state == "q0"
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def test_stay_direction(self):
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"""S direction should not move the head."""
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desc = {
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"states": ["q0", "halt"],
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"alphabet": ["a"],
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"blank": "_",
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"transitions": {"q0:a": ["halt", "b", "S"]},
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"start": "q0",
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"halt": "halt"
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}
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tm = TuringMachine(desc)
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tape = parse_tape("a", "_")
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final_tape, steps, state = tm.run(tape)
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assert state == "halt"
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assert final_tape[0] == "b"
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assert steps == 1
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