diff --git a/tests/time_stdlib_test.rs b/tests/time_stdlib_test.rs
index 29e9846a..bb7c6888 100644
--- a/tests/time_stdlib_test.rs
+++ b/tests/time_stdlib_test.rs
@@ -88,3 +88,107 @@ fn test_native_create_time_invalid_values() {
     let result = native_create_time(args);
     assert!(result.is_err(), "create_time should fail with second >= 60");
 }
+
+use chrono::{Local, NaiveDate};
+use std::rc::Rc;
+use wfl::stdlib::time::{native_add_days, native_create_date, native_days_between, native_today};
+
+#[test]
+fn test_native_today() {
+    let expected = Local::now().date_naive();
+    let result = native_today(vec![]);
+    assert!(result.is_ok());
+    if let Value::Date(d) = result.unwrap() {
+        assert_eq!(*d, expected);
+    } else {
+        panic!("Expected Date variant");
+    }
+}
+
+#[test]
+fn test_native_create_date_valid() {
+    let args = vec![
+        Value::Number(2023.0),
+        Value::Number(10.0),
+        Value::Number(25.0),
+    ];
+    let result = native_create_date(args);
+    assert!(result.is_ok());
+    if let Value::Date(d) = result.unwrap() {
+        assert_eq!(*d, NaiveDate::from_ymd_opt(2023, 10, 25).unwrap());
+    } else {
+        panic!("Expected Date variant");
+    }
+}
+
+#[test]
+fn test_native_create_date_invalid_month() {
+    let args = vec![
+        Value::Number(2023.0),
+        Value::Number(13.0), // Invalid month
+        Value::Number(25.0),
+    ];
+    let result = native_create_date(args);
+    assert!(result.is_err());
+}
+
+#[test]
+fn test_native_create_date_invalid_day() {
+    let args = vec![
+        Value::Number(2023.0),
+        Value::Number(10.0),
+        Value::Number(32.0), // Invalid day
+    ];
+    let result = native_create_date(args);
+    assert!(result.is_err());
+
+    let args_zero = vec![
+        Value::Number(2023.0),
+        Value::Number(10.0),
+        Value::Number(0.0), // Invalid day (too low)
+    ];
+    let result_zero = native_create_date(args_zero);
+    assert!(result_zero.is_err());
+}
+
+#[test]
+fn test_native_add_days() {
+    let start_date = Rc::new(NaiveDate::from_ymd_opt(2023, 10, 25).unwrap());
+    let args = vec![Value::Date(start_date), Value::Number(5.0)];
+    let result = native_add_days(args);
+    assert!(result.is_ok());
+    if let Value::Date(d) = result.unwrap() {
+        assert_eq!(*d, NaiveDate::from_ymd_opt(2023, 10, 30).unwrap());
+    } else {
+        panic!("Expected Date variant");
+    }
+}
+
+#[test]
+fn test_native_add_days_negative() {
+    let start_date = Rc::new(NaiveDate::from_ymd_opt(2023, 10, 25).unwrap());
+    let args = vec![Value::Date(start_date), Value::Number(-5.0)];
+    let result = native_add_days(args);
+    assert!(result.is_ok());
+    if let Value::Date(d) = result.unwrap() {
+        assert_eq!(*d, NaiveDate::from_ymd_opt(2023, 10, 20).unwrap());
+    } else {
+        panic!("Expected Date variant");
+    }
+}
+
+#[test]
+fn test_native_days_between() {
+    let date1 = Rc::new(NaiveDate::from_ymd_opt(2023, 10, 20).unwrap());
+    let date2 = Rc::new(NaiveDate::from_ymd_opt(2023, 10, 25).unwrap());
+
+    // date1 is older, date2 is newer
+    let args = vec![Value::Date(date1), Value::Date(date2)];
+    let result = native_days_between(args);
+    assert!(result.is_ok());
+    if let Value::Number(n) = result.unwrap() {
+        assert_eq!(n, 5.0);
+    } else {
+        panic!("Expected Number variant");
+    }
+}