feat: update structure

cs2030s/labs/Lab5/Test2.java

@@ -0,0 +1,72 @@
+import java.io.PrintStream;
+import java.io.ByteArrayOutputStream;
+
+public class Test2 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    PrintStream old = System.out;
+    ByteArrayOutputStream baos;
+    PrintStream ps;
+    
+    cs2030s.fp.Constant<Integer> zero = new cs2030s.fp.Constant<>() {
+      public Integer init() {
+        return 0;
+      }
+    };
+    cs2030s.fp.Action<Integer> print = new cs2030s.fp.Action<>() {
+      public void call(Integer i) {
+        System.out.println(i);
+      }
+    };
+    
+    try {
+      we.expect(
+        "Actually.<Number>ok(0).unwrap()",
+        cs2030s.fp.Actually.<Number>ok(0).unwrap().toString(),
+        "0"
+      );
+    } catch(Exception e) {
+      System.out.println("Unexpected error occurs");
+    }
+    
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    cs2030s.fp.Actually.<Integer>ok(9).finish(print);
+    we.expectPrint("Actually.<Integer>ok(9).finish(print)",
+                   "9",
+                   baos,
+                   old);
+                   
+    baos = new ByteArrayOutputStream();
+    ps = new PrintStream(baos);
+    System.setOut(ps);
+    cs2030s.fp.Actually.<Integer>err(new Exception("Err")).finish(print);
+    we.expectPrint("Actually.<Integer>err(new Exception(\"Err\")).finish(print)",
+                   "",
+                   baos,
+                   old);
+    
+    we.expect(
+      "Actually.<Number>ok(9).except(zero)",
+      cs2030s.fp.Actually.<Number>ok(9).except(zero).toString(),
+      "9"
+    );
+    we.expect(
+      "Actually.<Number>err(new ArithmeticException(\"div by 0\")).except(zero)",
+      cs2030s.fp.Actually.<Number>err(new ArithmeticException("div by 0")).except(zero).toString(),
+      "0"
+    );
+    
+    we.expect(
+      "Actually.<Number>err(new ArithmeticException(\"div by 0\")).unless(4)",
+      cs2030s.fp.Actually.<Number>err(new ArithmeticException("div by 0")).unless(4).toString(),
+      "4"
+    );
+    we.expect(
+      "Actually.<Number>ok(0).unless(4)",
+      cs2030s.fp.Actually.<Number>ok(0).unless(4).toString(),
+      "0"
+    );
+  }
+}