feat: update structure

cs2030s/labs/Lab7/Test2.java

@@ -0,0 +1,50 @@
+import cs2030s.fp.Combiner;
+import cs2030s.fp.Memo;
+
+public class Test2 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    int[] eval = new int[]{0};
+    Combiner<Integer, Integer, Integer> fib = (x, y) -> {
+      eval[0] += 1;
+      return x + y;
+    };
+    
+    MemoList<Integer> l = MemoList.generate(8, 0, 1, fib);
+    
+    we.expect(
+      "An initial MemoList only has the first two values evaluated",
+      l.toString(),
+      "[0, 1, ?, ?, ?, ?, ?, ?]"
+    );
+    
+    l.indexOf(5);
+    we.expect(
+      "Looking for 5 causes 4 evaluations",
+      eval[0],
+      4
+    );
+    
+    l.indexOf(3);
+    we.expect(
+      "Looking for 3 does not need any more evaluation",
+      eval[0],
+      4
+    );
+    
+    l.get(4);
+    we.expect(
+      "Retrieving index 4 does not need any more evaluation",
+      eval[0],
+      4
+    );
+    
+    l.get(6);
+    we.expect(
+      "Retrieving 6 causes one more evaluation",
+      eval[0],
+      5
+    );
+  }
+}