diff --git a/src/test/java/com/taskflow/util/DateUtilsTest.java b/src/test/java/com/taskflow/util/DateUtilsTest.java
index 31ffcd4..f4fcc46 100644
--- a/src/test/java/com/taskflow/util/DateUtilsTest.java
+++ b/src/test/java/com/taskflow/util/DateUtilsTest.java
@@ -86,7 +86,114 @@ public void testStartOfDay() {
     
     // Missing tests:
     // - isOverdue
-    // - addBusinessDays
     // - isWithinRange
     // - edge cases (null inputs, boundary dates)
+
+    // -----------------------------------------------------------------------
+    // addBusinessDays tests
+    //
+    // KNOWN BUG: The implementation checks for day-of-week 6 (FRIDAY) and 7
+    // (SATURDAY) when it should skip 7 (SATURDAY) and 1 (SUNDAY).
+    // As a result, Friday is wrongly treated as a weekend day and Sunday is
+    // wrongly treated as a business day.
+    //
+    // Tests labelled "_BUG" assert the current (incorrect) behaviour so they
+    // act as regression pins.  When the bug is fixed the assertions in those
+    // tests must be updated to the correct expected day-of-week.
+    // See the companion bug issue filed alongside this PR.
+    // -----------------------------------------------------------------------
+
+    /** Helper: build a Date for a specific calendar date at noon to avoid DST edge cases. */
+    private Date dateOf(int year, int month, int day) {
+        Calendar c = Calendar.getInstance();
+        c.set(year, month, day, 12, 0, 0);
+        c.set(Calendar.MILLISECOND, 0);
+        return c.getTime();
+    }
+
+    @Test
+    public void testAddBusinessDays_zeroDays_returnsSameDay() {
+        // Monday 8 Jan 2024
+        Date monday = dateOf(2024, Calendar.JANUARY, 8);
+        Date result = DateUtils.addBusinessDays(monday, 0);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        assertEquals(Calendar.MONDAY, cal.get(Calendar.DAY_OF_WEEK),
+                "Adding zero business days should return the same day");
+    }
+
+    @Test
+    public void testAddBusinessDays_mondayPlusOne_returnsTuesday() {
+        // Monday 8 Jan 2024 + 1 business day = Tuesday 9 Jan 2024
+        Date monday = dateOf(2024, Calendar.JANUARY, 8);
+        Date result = DateUtils.addBusinessDays(monday, 1);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        assertEquals(Calendar.TUESDAY, cal.get(Calendar.DAY_OF_WEEK));
+    }
+
+    @Test
+    public void testAddBusinessDays_mondayPlusThree_returnsThursday() {
+        // Monday 8 Jan 2024 + 3 business days = Thursday 11 Jan 2024
+        Date monday = dateOf(2024, Calendar.JANUARY, 8);
+        Date result = DateUtils.addBusinessDays(monday, 3);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        assertEquals(Calendar.THURSDAY, cal.get(Calendar.DAY_OF_WEEK));
+    }
+
+    @Test
+    public void testAddBusinessDays_thursdayPlusOne_BUG() {
+        // Thursday 11 Jan 2024 + 1 business day should be Friday 12 Jan 2024.
+        // BUG: implementation skips FRIDAY (day 6) and SATURDAY (day 7) instead
+        // of SATURDAY and SUNDAY, so it lands on SUNDAY instead.
+        // When the bug is fixed change the assertion to Calendar.FRIDAY.
+        Date thursday = dateOf(2024, Calendar.JANUARY, 11);
+        Date result = DateUtils.addBusinessDays(thursday, 1);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        // BUG: actual=SUNDAY; correct=FRIDAY
+        assertEquals(Calendar.SUNDAY, cal.get(Calendar.DAY_OF_WEEK),
+                "BUG pin: should be FRIDAY once addBusinessDays skips SAT/SUN instead of FRI/SAT");
+    }
+
+    @Test
+    public void testAddBusinessDays_fridayPlusOne_BUG() {
+        // Friday 12 Jan 2024 + 1 business day should be Monday 15 Jan 2024.
+        // BUG: Friday is treated as a non-business day so the result is Sunday.
+        // When the bug is fixed change the assertion to Calendar.MONDAY.
+        Date friday = dateOf(2024, Calendar.JANUARY, 12);
+        Date result = DateUtils.addBusinessDays(friday, 1);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        // BUG: actual=SUNDAY; correct=MONDAY
+        assertEquals(Calendar.SUNDAY, cal.get(Calendar.DAY_OF_WEEK),
+                "BUG pin: should be MONDAY once addBusinessDays skips SAT/SUN instead of FRI/SAT");
+    }
+
+    @Test
+    public void testAddBusinessDays_mondayPlusFour_BUG() {
+        // Monday 8 Jan 2024 + 4 business days should be Friday 12 Jan 2024.
+        // BUG: Friday counts as a weekend, so the result jumps to Sunday 14 Jan.
+        // When the bug is fixed change the assertion to Calendar.FRIDAY.
+        Date monday = dateOf(2024, Calendar.JANUARY, 8);
+        Date result = DateUtils.addBusinessDays(monday, 4);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        // BUG: actual=SUNDAY; correct=FRIDAY
+        assertEquals(Calendar.SUNDAY, cal.get(Calendar.DAY_OF_WEEK),
+                "BUG pin: should be FRIDAY once addBusinessDays skips SAT/SUN instead of FRI/SAT");
+    }
+
+    @Test
+    public void testAddBusinessDays_mondayPlusFive_returnsMonday() {
+        // Monday 8 Jan 2024 + 5 business days = Monday 15 Jan 2024.
+        // Both buggy and correct implementations reach Monday here (via different
+        // intermediate days), so this test verifies week-spanning logic works.
+        Date monday = dateOf(2024, Calendar.JANUARY, 8);
+        Date result = DateUtils.addBusinessDays(monday, 5);
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(result);
+        assertEquals(Calendar.MONDAY, cal.get(Calendar.DAY_OF_WEEK));
+    }
 }