diff --git a/README.md b/README.md
index 56f9a02..9923c86 100644
--- a/README.md
+++ b/README.md
@@ -146,6 +146,7 @@ $ sh boot.sh
 
 ### 其它支持与不支持
 
+- 不允许在一个声明中声明多个变量或函数（如 `int a, b;`）请写成多个声明。
 - 支持全局变量和局部变量，局部变量遮挡全局变量。
 - 不支持局部变量之间的遮挡，重名的局部变量为同一变量。
 - 函数只支持最多八个参数。函数声明中支持可变参数，仅用于兼容 C 语言库。
diff --git a/test.sh b/test.sh
index 7025834..5a82fef 100644
--- a/test.sh
+++ b/test.sh
@@ -15,6 +15,7 @@ for i in *.c; do
         rm $i.ans
     else
         echo "Test '$i' failed"
+        exit 1
     fi
 done
 echo "Passed $succ/$all tests"
diff --git a/test/enum.c b/test/enum.c
index 145b98b..7b53339 100644
--- a/test/enum.c
+++ b/test/enum.c
@@ -1,5 +1,5 @@
 enum {
-    A, B, C = 1, D, E = A, F
+    A, B, C = 1, D, E = A, F,
 };
 
 int main() {
diff --git a/test/escape.c b/test/escape.c
index 8a0d33e..92cf816 100644
--- a/test/escape.c
+++ b/test/escape.c
@@ -1,9 +1,11 @@
 int getchar();
 int putchar(int ch);
-int printf(char* format, ...); 
+int fprintf(void* file, char* format, ...); 
+extern void* stdout;
+
 
 int main() {
-    int ch;
+    char ch = 0["\t\r\""];;
     while ((ch = getchar()) != -1) {
         if (ch == '\\') {
             ch = getchar();
@@ -22,7 +24,7 @@ int main() {
             } else if (ch == '\"') {
                 ch = '\"';
             } else {
-                printf("unexpected escaped character: '\\%c'\n", ch);
+                fprintf(stdout, "unexpected escaped character: '\\%c'\n", ch);
                 return 1;
             }
         }
diff --git a/test/inc.c b/test/inc.c
new file mode 100644
index 0000000..d39c5d3
--- /dev/null
+++ b/test/inc.c
@@ -0,0 +1,14 @@
+int printf(char* format, ...);
+
+int main() {
+    int a = 4;
+    printf("a = %d\n", a);
+    printf("a++ = %d\n", a++);
+    printf("a = %d\n", a);
+    printf("++a = %d\n", ++a);
+    printf("a = %d\n", a);
+    printf("a-- = %d\n", a--);
+    printf("a = %d\n", a);
+    printf("--a = %d\n", --a);
+    printf("a = %d\n", a);
+}
\ No newline at end of file
diff --git a/test/inc.in b/test/inc.in
new file mode 100644
index 0000000..e69de29
diff --git a/test/inc.out b/test/inc.out
new file mode 100644
index 0000000..33429d9
--- /dev/null
+++ b/test/inc.out
@@ -0,0 +1,10 @@
+a = 4
+a++ = 4
+a = 5
+++a = 6
+a = 6
+a-- = 6
+a = 5
+--a = 4
+a = 4
+0
diff --git a/test/loop.c b/test/loop.c
index 98c3e21..6ef9347 100644
--- a/test/loop.c
+++ b/test/loop.c
@@ -81,7 +81,25 @@ void test_break() {
     printf("\n");
 }
 
+void test_nested() {
+    int i; 
+    int j;
+
+    // For loop
+    printf("For loop:\n");
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
+            if (i >= 2 && j >= 2 && i + j >= 5) {
+                return; // Exit nested loop via return
+            }
+            printf("(%d, %d) ", i, j);
+        }
+        printf("\n");
+    }
+}
+
 int main() {
     test_continue();
     test_break();
+    test_nested();
 }
\ No newline at end of file
diff --git a/test/loop.out b/test/loop.out
index 460695d..1c18926 100644
--- a/test/loop.out
+++ b/test/loop.out
@@ -10,4 +10,7 @@ While loop:
 0 1 2 
 Do-while loop:
 0 1 2 
-0
+For loop:
+(0, 0) (0, 1) (0, 2) (0, 3) (0, 4) 
+(1, 0) (1, 1) (1, 2) (1, 3) (1, 4) 
+(2, 0) (2, 1) (2, 2) 0
diff --git a/test/overflow.c b/test/overflow.c
index a580076..1d12c64 100644
--- a/test/overflow.c
+++ b/test/overflow.c
@@ -1,5 +1,41 @@
-int main() {
-    int placeholder[1024];
-    int a = 1;
-    return (a=(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(0)))))))))))))))))))))), (a = a);
+int printf(char* format, ...);
+
+
+enum {
+    a = 1
+};
+
+int get_20() {
+    return (a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(- -0)))))))))))))))))))));
+}
+
+void dummy(int a0, int a1, int a2, int a3, int a4, int a5, int a6, int a7) {
+    a0 += a1;
+    printf("%d\n", a0);
+    a0 -= a1;
+    printf("%d\n", a0);
+    a0 *= a1;
+    printf("%d\n", a0);
+    a0 /= a1;
+    printf("%d\n", a0);
+    a0 %= a1;
+    printf("%d\n", a0);
+    a0 &= a1;
+    printf("%d\n", a0);
+    a0 |= a1;
+    printf("%d\n", a0);
+    a0 ^= a2;
+    printf("%d\n", a0);
+    a0 <<= a1;
+    printf("%d\n", a0);
+    a0 >>= a1;
+    printf("%d\n", a0);
+}
+
+
+int main() {
+    char placeholder[4096];
+    int a = 1;
+    dummy((a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(! !0))))))))))))))))))))), 3, a, a, a, a, a, a);
+    return (a=(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(a+(~ ~0)))))))))))))))))))))), (a = a);
 }
diff --git a/test/overflow.out b/test/overflow.out
index 209e3ef..1c9bef7 100644
--- a/test/overflow.out
+++ b/test/overflow.out
@@ -1 +1,11 @@
+23
+20
+60
+20
+2
+2
+3
+2
+16
+2
 20
diff --git a/test/short.c b/test/short.c
new file mode 100644
index 0000000..6602908
--- /dev/null
+++ b/test/short.c
@@ -0,0 +1,17 @@
+int printf(char* format, ...);
+
+int f(int i) {
+    printf("f(%d)\n", i);
+    return i % 2;
+}
+
+int main() {
+    1 && f(1);
+    0 && f(2);
+    1 || f(3);
+    0 || f(4);
+    1 ? f(5) : f(6);
+    0 ? f(7) : f(8);
+    1 && f(9) || f(10);
+    0 && f(11) || f(12);
+}
\ No newline at end of file
diff --git a/test/short.in b/test/short.in
new file mode 100644
index 0000000..e69de29
diff --git a/test/short.out b/test/short.out
new file mode 100644
index 0000000..68ecb28
--- /dev/null
+++ b/test/short.out
@@ -0,0 +1,7 @@
+f(1)
+f(4)
+f(5)
+f(8)
+f(9)
+f(12)
+0
diff --git a/test/sort.c b/test/sort.c
index b0793f0..970571f 100644
--- a/test/sort.c
+++ b/test/sort.c
@@ -1,21 +1,40 @@
 int printf(char* format, ...);
 int scanf(char* format, ...);
+int exit(int status);
+
+void assert_eq(int expected, int actual) {
+    if (expected != actual) {
+        printf("expected: %d, actual: %d\n", expected, actual);
+        exit(1);
+    }
+}
+
+void swap(int* a, int* b) {
+    int t = *a;
+    *a = *b;
+    *b = t;
+}
 
 void sort(int a[], int n) {
     for (int i = 0; i < n; i++) {
         for (int j = i + 1; j < n; j++) {
             if (a[i] > a[j]) {
-                int t = a[i];
-                a[i] = a[j];
-                a[j] = t;
+                swap(&a[i], &a[j]);
+                assert_eq(i - j, &a[i] - &a[j]);
+                assert_eq(j - i, &a[j] - &a[i]);
+                assert_eq(a[i], *(a + i));
+                assert_eq(i[a], *(i + a));
+                assert_eq(a[j - i], *(a + (j - i)));
+                assert_eq(j[a - i], *(j + (a - i)));
             }
         }
     }
 }
 
+int a[100];
+int n;
+
 int main() {
-    int n;
-    int a[100];
     scanf("%d", &n);
     for (int i = 0; i < n; i++) {
         scanf("%d", &a[i]);