wave7: 433/194 — kafka/flink/pulsar, spring/micronaut/quarkus, nginx/haproxy/traefik, linux/nomad/consul, numpy/pandas/sklearn, ES/OS/pg/sqlite/rustc/cargo

defects/pandas/unit/PandasTest.java

@@ -0,0 +1,108 @@
+package unit;
+
+import java.util.*;
+
+/**
+ * Standalone unit tests for pandas CWE-407 defects.
+ *
+ * pandas-0001: Styler render — O(R×H) hidden_rows list membership in render loops
+ *   Simulates: [r for r in range(len(index)) if r not in self.hidden_rows]
+ *   and the body-cell loop: if r not in self.hidden_rows (O(H) per row).
+ *   slow(): list.contains(r) per row iteration — O(R×H)
+ *   fast(): HashSet.contains(r) per row iteration — O(R)
+ *   Assert: slowOps >= fastOps * 10 for R=2000 rows, H=500 hidden rows
+ */
+public class PandasTest {
+
+    // ── pandas-0001 ───────────────────────────────────────────────────────────
+
+    /**
+     * Slow path: hidden rows stored as a List<Integer>.
+     * Each membership test scans up to H entries — O(H) per row.
+     * Total for R rows: O(R × H).
+     *
+     * @param totalRows   total row count R
+     * @param hiddenRows  set of hidden row indices (stored as list)
+     * @return op count (each element comparison in list.contains() = 1 op)
+     */
+    static long slowRenderRows(int totalRows, List<Integer> hiddenRows) {
+        long ops = 0;
+        List<Integer> visibleRows = new ArrayList<>();
+
+        for (int r = 0; r < totalRows; r++) {
+            // Mirrors: if r not in self.hidden_rows — linear scan
+            boolean found = false;
+            for (int i = 0; i < hiddenRows.size(); i++) {
+                ops++;
+                if (hiddenRows.get(i) == r) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                visibleRows.add(r);
+            }
+        }
+        return ops;
+    }
+
+    /**
+     * Fast path: hidden rows stored as a HashSet<Integer>.
+     * Each membership test is O(1). Total for R rows: O(R + H).
+     *
+     * @param totalRows   total row count R
+     * @param hiddenRows  set of hidden row indices (stored as list — converted once)
+     * @return op count (1 op per row for set.contains + 1 op per hidden row to build set)
+     */
+    static long fastRenderRows(int totalRows, List<Integer> hiddenRows) {
+        long ops = 0;
+        List<Integer> visibleRows = new ArrayList<>();
+
+        // Build set once: O(H)
+        Set<Integer> hiddenSet = new HashSet<>(hiddenRows.size() * 2);
+        for (int h : hiddenRows) {
+            hiddenSet.add(h);
+            ops++;
+        }
+
+        for (int r = 0; r < totalRows; r++) {
+            ops++;                              // O(1) set.contains
+            if (!hiddenSet.contains(r)) {
+                visibleRows.add(r);
+            }
+        }
+        return ops;
+    }
+
+    static void testRenderRows() {
+        int R = 2000;   // total rows
+        int H = 500;    // hidden rows (scattered through the middle — maximizes scan depth)
+
+        List<Integer> hiddenRows = new ArrayList<>(H);
+        // Hidden rows in the range [R/4, R/4+H) — they appear late in the list
+        for (int i = R / 4; i < R / 4 + H; i++) hiddenRows.add(i);
+
+        long slowOps = slowRenderRows(R, hiddenRows);
+        long fastOps = fastRenderRows(R, hiddenRows);
+
+        System.out.printf(
+            "pandas-0001  R=%-5d H=%-4d  slowOps=%-8d  fastOps=%-6d  ratio=%.1fx%n",
+            R, H, slowOps, fastOps, (double) slowOps / fastOps
+        );
+
+        assert slowOps > fastOps * 10 :
+            "pandas-0001 FAIL: expected slowOps > 10×fastOps, got " + slowOps + " vs " + fastOps;
+        System.out.println("pandas-0001  PASS");
+    }
+
+    // ── main ──────────────────────────────────────────────────────────────────
+
+    public static void main(String[] args) {
+        int pass = 0, total = 1;
+
+        try { testRenderRows(); pass++; } catch (AssertionError e) { System.err.println(e.getMessage()); }
+
+        System.out.printf("%n%d/%d PASS%n", pass, total);
+        if (pass != total) System.exit(1);
+    }
+}