java-topology/defects/element-web/unit/ElementWebTest.java

import java.util.*;

/**
 * CWE-407 unit tests for element-web (Matrix client) defects.
 *
 * element-web-0001: TextForEvent.tsx textForPowerEvent()
 *   users array + indexOf for dedup → O(U²)
 *   Fix: Set-based dedup → O(U)
 *
 * element-web-0002: TextForEvent.tsx textForPinnedEvent()
 *   previouslyPinned.indexOf inside filter → O(P×Q)
 *   Fix: Set.has() inside filter → O(P+Q)
 */
public class ElementWebTest {

    // --- element-web-0001: user dedup ---

    static List<String> deduplicateUsersArray(String[] current, String[] previous) {
        List<String> users = new ArrayList<>();
        for (String u : current) {
            if (!users.contains(u)) users.add(u);     // O(U) per user
        }
        for (String u : previous) {
            if (!users.contains(u)) users.add(u);
        }
        return users;
    }

    static List<String> deduplicateUsersSet(String[] current, String[] previous) {
        Set<String> seen = new LinkedHashSet<>();     // preserves insertion order
        for (String u : current) seen.add(u);
        for (String u : previous) seen.add(u);
        return new ArrayList<>(seen);
    }

    static void testElementWeb0001() throws Exception {
        int U = 1000;
        String[] current  = new String[U];
        String[] previous = new String[U];
        for (int i = 0; i < U; i++) {
            current[i]  = "@user" + i + ":matrix.org";
            previous[i] = "@user" + (i + U / 2) + ":matrix.org";  // partial overlap
        }

        // correctness
        List<String> rArr = deduplicateUsersArray(current, previous);
        List<String> rSet = deduplicateUsersSet(current, previous);
        Collections.sort(rArr);
        Collections.sort(rSet);
        assert rArr.equals(rSet) : "array and set must produce same user list";

        // performance
        long t0 = System.nanoTime();
        for (int r = 0; r < 200; r++) deduplicateUsersArray(current, previous);
        long tArr = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int r = 0; r < 200; r++) deduplicateUsersSet(current, previous);
        long tSet = System.nanoTime() - t0;

        double ratio = (double) tArr / tSet;
        System.out.printf("element-web-0001: array=%.3fs set=%.3fs ratio=%.1f×%n",
                tArr / 1e9, tSet / 1e9, ratio);
        assert ratio > 10 : "Expected >10× speedup, got " + ratio;
        System.out.println("PASS element-web-0001");
    }

    // --- element-web-0002: pinned messages filter ---

    static List<String> newlyPinnedIndexOf(List<String> pinned, List<String> previouslyPinned) {
        List<String> result = new ArrayList<>();
        for (String item : pinned) {
            if (!previouslyPinned.contains(item)) result.add(item);  // O(P) per item
        }
        return result;
    }

    static List<String> newlyPinnedSet(List<String> pinned, List<String> previouslyPinned) {
        Set<String> prevSet = new HashSet<>(previouslyPinned);       // O(1) lookup
        List<String> result = new ArrayList<>();
        for (String item : pinned) {
            if (!prevSet.contains(item)) result.add(item);
        }
        return result;
    }

    static void testElementWeb0002() throws Exception {
        int P = 1000;
        List<String> pinned = new ArrayList<>();
        List<String> previouslyPinned = new ArrayList<>();
        for (int i = 0; i < P; i++) {
            pinned.add("$event" + i);
            previouslyPinned.add("$event" + (i + P / 2));
        }

        // correctness
        List<String> r1 = newlyPinnedIndexOf(pinned, previouslyPinned);
        List<String> r2 = newlyPinnedSet(pinned, previouslyPinned);
        Collections.sort(r1);
        Collections.sort(r2);
        assert r1.equals(r2) : "indexOf and set paths must agree";

        // performance
        long t0 = System.nanoTime();
        for (int r = 0; r < 200; r++) newlyPinnedIndexOf(pinned, previouslyPinned);
        long tIndexOf = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int r = 0; r < 200; r++) newlyPinnedSet(pinned, previouslyPinned);
        long tSet = System.nanoTime() - t0;

        double ratio = (double) tIndexOf / tSet;
        System.out.printf("element-web-0002: indexOf=%.3fs set=%.3fs ratio=%.1f×%n",
                tIndexOf / 1e9, tSet / 1e9, ratio);
        assert ratio > 5 : "Expected >5× speedup, got " + ratio;
        System.out.println("PASS element-web-0002");
    }

    public static void main(String[] args) throws Exception {
        testElementWeb0001();
        testElementWeb0002();
        System.out.println("ALL PASS");
    }
}