修复了大量存在的问题，增加了假鸭子类型等等机制

Test/IterTest/App/main.py

@@ -1,35 +1,30 @@
 import t
 import stdio
 import string
+import testcheck
 
 def test_for_in_string():
-    stdio.printf("--- Test 1: for-in string iteration ---\n")
+    testcheck.section("Test 1: for-in string iteration")
     s: t.CChar | t.CPtr = "Hello"
     result: t.CInt = 0
     for ch in s:
         result += ch
     # H=72, e=101, l=108, l=108, o=111 => 500
-    if result == 500:
-        stdio.printf("PASS: for-in string (sum=%d)\n", result)
-    else:
-        stdio.printf("FAIL: for-in string (sum=%d, expect 500)\n", result)
+    testcheck.check(result == 500, "for-in string (sum=500)", "for-in string (sum expect 500)")
 
 def test_for_in_char_ptr():
-    stdio.printf("--- Test 2: for-in char* iteration ---\n")
+    testcheck.section("Test 2: for-in char* iteration")
     s: t.CChar | t.CPtr = "ABC"
-    chars: list[t.CInt, 4] = [0]
+    chars: t.CArray[t.CInt, 4] = [0]
     idx: t.CInt = 0
     for ch in s:
         if idx < 3:
             chars[idx] = ch
         idx += 1
-    if chars[0] == 65 and chars[1] == 66 and chars[2] == 67:
-        stdio.printf("PASS: for-in char* (A=%d B=%d C=%d)\n", chars[0], chars[1], chars[2])
-    else:
-        stdio.printf("FAIL: for-in char* (A=%d B=%d C=%d, expect 65 66 67)\n", chars[0], chars[1], chars[2])
+    testcheck.check(chars[0] == 65 and chars[1] == 66 and chars[2] == 67, "for-in char* (A=65 B=66 C=67)", "for-in char* (expect A=65 B=66 C=67)")
 
 def test_strcpy_for_in():
-    stdio.printf("--- Test 3: strcpy using for-in ---\n")
+    testcheck.section("Test 3: strcpy using for-in")
     src: t.CChar | t.CPtr = "test"
     # 手动实现 strcpy 用 for-in
     import w32.win32memory
@@ -45,17 +40,13 @@ def test_strcpy_for_in():
         p += 1
     p[0] = 0
     cmp_result: t.CInt = string.strcmp(buf, "test")
-    if cmp_result == 0:
-        stdio.printf("PASS: strcpy for-in (result=%s)\n", buf)
-    else:
-        stdio.printf("FAIL: strcpy for-in (cmp=%d)\n", cmp_result)
+    testcheck.check(cmp_result == 0, "strcpy for-in (result=test)", "strcpy for-in (cmp mismatch)")
 
 import w32.win32memory
 
 def main() -> t.CInt:
-    stdio.printf("=== IterTest: 指针迭代测试 ===\n\n")
+    testcheck.begin("IterTest: 指针迭代测试")
     test_for_in_string()
     test_for_in_char_ptr()
     test_strcpy_for_in()
-    stdio.printf("\n=== IterTest Complete ===\n")
-    return 0
+    return testcheck.end()