java-topology/tests/unit/Moad0002UnitTest.java

package unit;

import support.Moad0002Algorithm;
import support.Moad0002Algorithm.Context;
import support.Moad0002Algorithm.DefectiveAudioSystem;
import support.Moad0002Algorithm.DefectiveDisplaySystem;
import support.Moad0002Algorithm.FixedAudioSystem;
import support.Moad0002Algorithm.FixedDisplaySystem;

/**
 * Unit tests for MOAD-0002: An Intertangled Defect.
 *
 * Proves from first principles:
 *   1. Defective: AudioSystem.setLocale() mutates state seen by DisplaySystem —
 *      cross-subsystem interference through shared global state.
 *   2. Defective: two independent "contexts" sharing GLOBAL cannot coexist —
 *      the second write tramples the first silently.
 *   3. Fixed: two Context objects carry independent values simultaneously.
 *   4. Fixed: AudioSystem and DisplaySystem read from separate Context objects
 *      without interfering with each other.
 *
 * No build tool required. Compile and run:
 *
 *   cd tests
 *   java -m jdk.compiler/com.sun.tools.javac.Main -cp . \
 *        support/Moad0002Algorithm.java unit/Moad0002UnitTest.java
 *   java -cp . unit.Moad0002UnitTest
 */
public class Moad0002UnitTest {

    private static int passed = 0;
    private static int failed = 0;

    public static void main(String[] args) {
        System.out.println("=== Moad0002UnitTest (An Intertangled Defect) ===\n");

        System.out.println("-- Correctness: subsystems read values correctly --");
        testDefectiveBasicRead();
        testFixedBasicRead();

        System.out.println("\n-- Defect: shared global state causes cross-subsystem interference --");
        testDefectiveAudioLocaleLeaksToDisplay();
        testDefectiveTwoContextsTrample();

        System.out.println("\n-- Fix: isolated Context objects prevent interference --");
        testFixedTwoContextsCoexist();
        testFixedSubsystemsDoNotInterfere();

        System.out.printf("\n%d passed, %d failed%n", passed, failed);
        if (failed > 0) System.exit(1);
    }

    // ── Correctness ───────────────────────────────────────────────────────────

    static void testDefectiveBasicRead() {
        Moad0002Algorithm.resetGlobal();
        DefectiveAudioSystem audio = new DefectiveAudioSystem();
        audio.setVolume(80);
        assertEqual("defective audio: volume reads back correctly", 80, audio.getVolume());
    }

    static void testFixedBasicRead() {
        Context ctx = new Context(70, 200, "fr");
        FixedAudioSystem    audio   = new FixedAudioSystem(ctx);
        FixedDisplaySystem  display = new FixedDisplaySystem(ctx);
        assertEqual("fixed audio: volume", 70, audio.getVolume());
        assertEqual("fixed display: brightness", 200, display.getBrightness());
        assertEqual("fixed audio: locale", "fr", audio.getLocale());
        assertEqual("fixed display: locale", "fr", display.getLocale());
    }

    // ── Defect ────────────────────────────────────────────────────────────────

    static void testDefectiveAudioLocaleLeaksToDisplay() {
        Moad0002Algorithm.resetGlobal();
        DefectiveAudioSystem   audio   = new DefectiveAudioSystem();
        DefectiveDisplaySystem display = new DefectiveDisplaySystem();

        // AudioSystem configures locale — conceptually an audio concern (TTS language)
        audio.setLocale("ja");

        // DEFECT: DisplaySystem reads the same global — sees audio's mutation
        // This is the intertangle: two subsystems that should be independent
        // are coupled through a shared mutable state object.
        String displayLocale = display.getLocale();
        assertEqual("defective: audio locale write leaks into display", "ja", displayLocale);
    }

    static void testDefectiveTwoContextsTrample() {
        Moad0002Algorithm.resetGlobal();
        // Two independent "sessions" each configure their own audio subsystem.
        DefectiveAudioSystem session1 = new DefectiveAudioSystem();
        DefectiveAudioSystem session2 = new DefectiveAudioSystem();

        session1.setVolume(30);   // session 1 sets volume to 30
        session2.setVolume(90);   // session 2 sets volume to 90 — TRAMPLES session 1

        // DEFECT: session 1 now sees 90, not 30 — its configuration was silently destroyed.
        // Two contexts cannot coexist when they share a global state object.
        int session1Volume = session1.getVolume();
        assertEqual("defective: session2 write tramples session1 volume", 90, session1Volume);
    }

    // ── Fix ───────────────────────────────────────────────────────────────────

    static void testFixedTwoContextsCoexist() {
        Context ctx1 = new Context(30, 150, "en");
        Context ctx2 = new Context(90, 200, "ja");

        FixedAudioSystem s1 = new FixedAudioSystem(ctx1);
        FixedAudioSystem s2 = new FixedAudioSystem(ctx2);

        // FIX: both values coexist — ctx1 and ctx2 are independent objects
        assertEqual("fixed: session1 volume preserved after session2 created", 30, s1.getVolume());
        assertEqual("fixed: session2 volume independent of session1",          90, s2.getVolume());
        assertEqual("fixed: session1 locale preserved",  "en", s1.getLocale());
        assertEqual("fixed: session2 locale independent", "ja", s2.getLocale());
    }

    static void testFixedSubsystemsDoNotInterfere() {
        Context audioCtx   = new Context(75, 0,   "de");
        Context displayCtx = new Context(0,  180,  "fr");

        FixedAudioSystem   audio   = new FixedAudioSystem(audioCtx);
        FixedDisplaySystem display = new FixedDisplaySystem(displayCtx);

        // FIX: each subsystem reads only its own context — no cross-contamination
        assertEqual("fixed: audio locale unaffected by display context", "de", audio.getLocale());
        assertEqual("fixed: display locale unaffected by audio context", "fr", display.getLocale());
        assertEqual("fixed: display brightness from own context", 180, display.getBrightness());
        assertEqual("fixed: audio volume from own context",        75, audio.getVolume());
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    static void assertEqual(String label, int expected, int actual) {
        if (expected == actual) {
            System.out.printf("  PASS: %s%n", label);
            passed++;
        } else {
            System.out.printf("  FAIL: %s — expected %d, got %d%n", label, expected, actual);
            failed++;
        }
    }

    static void assertEqual(String label, String expected, String actual) {
        if (expected == null ? actual == null : expected.equals(actual)) {
            System.out.printf("  PASS: %s%n", label);
            passed++;
        } else {
            System.out.printf("  FAIL: %s — expected '%s', got '%s'%n", label, expected, actual);
            failed++;
        }
    }
}