java-topology/defects/jitsi-meet-0003/unit/AvModerationPendingTest.java

import java.util.*;

/**
 * Unit test for jitsi-meet-0003: AV moderation pending participant dedup.
 *
 * Models the TypeScript reducer logic in Java to verify O(1) Map-based dedup
 * vs O(P) Array.find() dedup.
 *
 * Defect location:
 *   react/features/av-moderation/reducer.ts   line 210 (PARTICIPANT_PENDING_AUDIO)
 *   react/features/av-moderation/functions.ts line 129 (isParticipantPending)
 *
 * Compile and run:
 *   javac defects/jitsi-meet-0003/unit/AvModerationPendingTest.java
 *   java -cp defects/jitsi-meet-0003/unit AvModerationPendingTest
 */
public class AvModerationPendingTest {

    // --- Defective implementation: Array.find() for dedup ---

    static List<Map<String, String>> pendingArrayAdd(
            List<Map<String, String>> pending, Map<String, String> participant) {
        // O(P) linear scan — mirrors reducer.ts line 210
        boolean alreadyPresent = false;
        for (Map<String, String> p : pending) {
            if (p.get("id").equals(participant.get("id"))) {
                alreadyPresent = true;
                break;
            }
        }
        if (!alreadyPresent) {
            List<Map<String, String>> updated = new ArrayList<>(pending);
            updated.add(participant);
            return updated;
        }
        return pending;
    }

    static boolean isPendingArray(List<Map<String, String>> pending, String id) {
        // O(P) — mirrors functions.ts line 129
        for (Map<String, String> p : pending) {
            if (p.get("id").equals(id)) return true;
        }
        return false;
    }

    // --- Fixed implementation: Map for O(1) dedup ---

    static Map<String, Map<String, String>> pendingMapAdd(
            Map<String, Map<String, String>> pending, Map<String, String> participant) {
        String id = participant.get("id");
        if (!pending.containsKey(id)) {
            Map<String, Map<String, String>> updated = new LinkedHashMap<>(pending);
            updated.put(id, participant);
            return updated;
        }
        return pending;
    }

    static boolean isPendingMap(Map<String, Map<String, String>> pending, String id) {
        return pending.containsKey(id);  // O(1)
    }

    // --- Helpers ---

    static Map<String, String> participant(String id) {
        Map<String, String> p = new HashMap<>();
        p.put("id", id);
        p.put("name", "Participant " + id);
        return p;
    }

    static void check(boolean condition, String msg) {
        if (!condition) throw new AssertionError("FAIL: " + msg);
    }

    public static void main(String[] args) {
        System.out.println("jitsi-meet-0003: AvModerationPendingTest");

        // Test 1: Array dedup correctness
        {
            List<Map<String, String>> pending = new ArrayList<>();
            pending = pendingArrayAdd(pending, participant("p1"));
            pending = pendingArrayAdd(pending, participant("p1"));  // duplicate
            pending = pendingArrayAdd(pending, participant("p2"));
            check(pending.size() == 2, "Array: duplicate must be rejected, got " + pending.size());
            check(isPendingArray(pending, "p1"), "Array: p1 must be present");
            check(isPendingArray(pending, "p2"), "Array: p2 must be present");
            check(!isPendingArray(pending, "p3"), "Array: p3 must be absent");
            System.out.println("  PASS test-1: array dedup correctness");
        }

        // Test 2: Map dedup correctness
        {
            Map<String, Map<String, String>> pending = new LinkedHashMap<>();
            pending = pendingMapAdd(pending, participant("p1"));
            pending = pendingMapAdd(pending, participant("p1"));  // duplicate
            pending = pendingMapAdd(pending, participant("p2"));
            check(pending.size() == 2, "Map: duplicate must be rejected, got " + pending.size());
            check(isPendingMap(pending, "p1"), "Map: p1 must be present");
            check(isPendingMap(pending, "p2"), "Map: p2 must be present");
            check(!isPendingMap(pending, "p3"), "Map: p3 must be absent");
            System.out.println("  PASS test-2: map dedup correctness");
        }

        // Test 3: Performance — count total comparisons (algorithmic, not timing)
        // Defective: adding P unique participants costs O(1)+O(2)+...+O(P) = O(P^2/2) comparisons
        // Fixed: O(P) hash lookups regardless of order
        {
            int P = 500;
            // Count comparison ops for array: each add scans the current list
            long arrayOps = 0;
            for (int size = 0; size < P; size++) {
                arrayOps += size;  // scan from 0..size-1 before confirming absent
            }
            // Count comparison ops for map: O(1) per add (hash)
            long mapOps = P;  // one hash + compare per add

            check(arrayOps > mapOps * 10,
                "Array O(P^2) ops=" + arrayOps + " must be >> map O(P) ops=" + mapOps);

            double ratio = (double) arrayOps / mapOps;
            System.out.printf("  PASS test-3: op-count P=%d | array %,d ops | map %,d ops | %.1fx%n",
                P, arrayOps, mapOps, ratio);
        }

        // Test 4: isParticipantPending lookup performance
        // Use a large enough list to make timing differences measurable
        {
            int P = 2000;
            int REPEATS = 500;
            List<Map<String, String>> arrayPending = new ArrayList<>();
            Map<String, Map<String, String>> mapPending = new LinkedHashMap<>();

            for (int i = 0; i < P; i++) {
                Map<String, String> p = participant("p" + i);
                arrayPending.add(p);
                mapPending.put(p.get("id"), p);
            }

            // warm-up
            for (int i = 0; i < P; i++) {
                isPendingArray(arrayPending, "p" + i);
                isPendingMap(mapPending, "p" + i);
            }

            long arrayStart = System.nanoTime();
            for (int r = 0; r < REPEATS; r++) {
                for (int i = 0; i < P; i++) {
                    isPendingArray(arrayPending, "p" + i);
                }
            }
            long arrayLookupTime = System.nanoTime() - arrayStart;

            long mapStart = System.nanoTime();
            for (int r = 0; r < REPEATS; r++) {
                for (int i = 0; i < P; i++) {
                    isPendingMap(mapPending, "p" + i);
                }
            }
            long mapLookupTime = System.nanoTime() - mapStart;

            double ratio = (double) arrayLookupTime / mapLookupTime;
            System.out.printf("  PASS test-4: lookup P=%d x%d | array %,d ns | map %,d ns | %.1fx%n",
                P, REPEATS, arrayLookupTime, mapLookupTime, ratio);
            check(mapLookupTime < arrayLookupTime, "Map lookup must be faster than array scan P=" + P);
        }

        System.out.println("ALL 4 PASS");
    }
}