diff --git a/tests/unit/test_log.c b/tests/unit/test_log.c
index 23ea0ec..65fef67 100644
--- a/tests/unit/test_log.c
+++ b/tests/unit/test_log.c
@@ -53,14 +53,78 @@ void test_level_persistence(void) {
     TEST_ASSERT_EQUAL(LOG_LEVEL_INFO, log_get_level());
 }
 
+/* ===== log_* 函数不 crash ===== */
+
+void test_log_calls_no_crash(void) {
+    /* 正常调用各等级日志，确认不崩溃 */
+    log_set_level(LOG_LEVEL_DEBUG);
+    log_error("error %d", 1);
+    log_warn("warn %s", "x");
+    log_info("info %f", 1.0);
+    log_debug("debug %p", (void*)0);
+}
+
+/* ===== stderr 过滤测试 ===== */
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+
+void test_log_level_filter(void) {
+    /* 临时将 stderr 重定向到管道，验证高等级日志被过滤 */
+    int pipefd[2];
+    TEST_ASSERT_EQUAL(0, pipe(pipefd));
+
+    int old_stderr = dup(STDERR_FILENO);
+    dup2(pipefd[1], STDERR_FILENO);
+    close(pipefd[1]);
+
+    /* 设置 ERROR 级别，调用 INFO 不应输出 */
+    log_set_level(LOG_LEVEL_ERROR);
+    log_info("this should be filtered");
+
+    /* 恢复 stderr */
+    fflush(stderr);
+    dup2(old_stderr, STDERR_FILENO);
+    close(old_stderr);
+
+    /* 读取管道 */
+    char buf[256] = {0};
+    int n = read(pipefd[0], buf, sizeof(buf) - 1);
+    close(pipefd[0]);
+
+    /* INFO 被过滤，管道应无输出或只有前缀/时间（不含消息） */
+    if (n > 0) {
+        TEST_ASSERT_NULL(strstr(buf, "this should be filtered"));
+    }
+
+    /* ERROR 应正常输出 */
+    int pipefd2[2];
+    TEST_ASSERT_EQUAL(0, pipe(pipefd2));
+    old_stderr = dup(STDERR_FILENO);
+    dup2(pipefd2[1], STDERR_FILENO);
+    close(pipefd2[1]);
+
+    log_error("this is an error");
+
+    fflush(stderr);
+    dup2(old_stderr, STDERR_FILENO);
+    close(old_stderr);
+
+    char buf2[256] = {0};
+    n = read(pipefd2[0], buf2, sizeof(buf2) - 1);
+    close(pipefd2[0]);
+
+    TEST_ASSERT_GREATER_THAN(0, n);
+    TEST_ASSERT_NOT_NULL(strstr(buf2, "this is an error"));
+}
+
 void setUp(void) {
-    /* 每个测试前重置为默认 */
     log_set_level(LOG_LEVEL_INFO);
     log_set_prefix("[Cocoon]");
 }
 
 void tearDown(void) {
-    /* 每个测试后重置 */
     log_set_level(LOG_LEVEL_INFO);
     log_set_prefix("[Cocoon]");
 }
@@ -76,6 +140,8 @@ int main(void) {
     RUN_TEST(test_set_prefix);
     RUN_TEST(test_set_prefix_null);
     RUN_TEST(test_level_persistence);
+    RUN_TEST(test_log_calls_no_crash);
+    RUN_TEST(test_log_level_filter);
 
     return UNITY_END();
 }