Add tests to validate additional scenarios and also improve the branch coverage.

src/test/java/com/cronutils/mapper/WeekDayTest.java

@@ -65,4 +65,32 @@ public void testMapIntervalWithoutZeroStartingSunday() {
         final WeekDay target = new WeekDay(2, false);
         assertEquals(1, source.mapTo(value, target));
     }
+
+    @Test
+    public void testMapSourceWithZeroStartingMonday_TargetWithZeroNotStartingMonday() {
+        final WeekDay source = new WeekDay(0, true);
+        final WeekDay target = new WeekDay(1, true);
+        assertEquals(1, source.mapTo(6, target));
+    }
+
+    @Test
+    public void testMapSourceWithZeroStartingMonday_TargetWithZeroStartingMonday() {
+        final WeekDay source = new WeekDay(0, true);
+        final WeekDay target = new WeekDay(0, true);
+        assertEquals(6, source.mapTo(6, target));
+    }
+
+    @Test
+    public void testMapSourceWithZeroStartingMonday_TargetWithoutZeroStartingMonday() {
+        final WeekDay source = new WeekDay(0, true);
+        final WeekDay target = new WeekDay(1, false);
+        assertEquals(2, source.mapTo(1, target));
+    }
+
+    @Test
+    public void testMapSourceWithZeroStartingMonday_TargetWithoutZeroStartingSunday() {
+        final WeekDay source = new WeekDay(0, true);
+        final WeekDay target = new WeekDay(2, false);
+        assertEquals(2, source.mapTo(6, target));
+    }
 }

src/test/java/com/cronutils/model/field/expression/OnTest.java

@@ -80,4 +80,23 @@ public void testAsStringWithNth() {
         assertEquals(expression,
                 new On(new IntegerFieldValue(first), new SpecialCharFieldValue(SpecialChar.HASH), new IntegerFieldValue(second)).asString());
     }
+
+    @Test
+    public void testAsStringSpecialCharQuestionMark() {
+        final String expression = "?";
+        assertEquals(expression, new On(new SpecialCharFieldValue(SpecialChar.QUESTION_MARK)).asString());
+    }
+
+    @Test
+    public void testAsStringSpecialCharLWithTime() {
+        final int dayOfWeek = 5;
+        final String expression = String.format("%sL", dayOfWeek);
+        assertEquals(expression, new On(new IntegerFieldValue(dayOfWeek), new SpecialCharFieldValue(SpecialChar.L)).asString());
+    }
+
+    @Test
+    public void testAsStringSpecialCharWDefault() {
+        final String expression = "W";
+        assertEquals(expression, new On(new IntegerFieldValue(-1), new SpecialCharFieldValue(SpecialChar.W)).asString());
+    }
 }

src/test/java/com/cronutils/model/time/TimeNodeTest.java

@@ -103,6 +103,37 @@ public void testGetValueFromListWithEmptyList() {
         assertThrows(IllegalArgumentException.class, () -> timeNode.getValueFromList(new ArrayList<>(), 0, new AtomicInteger(0)));
     }
 
+    @Test
+    public void testGetValueFromListWithLargeIndices() {
+        final List<Integer> values = Arrays.asList(2, 8, 14, 20);
+        final AtomicInteger shift = new AtomicInteger(0);
+
+        final int largePositiveIndex = 365 * 6; 
+        int value = timeNode.getValueFromList(values, largePositiveIndex, shift);
+        assertEquals(14, value);
+        assertEquals(547, shift.get());
+
+        shift.set(0);
+        final int largeNegativeIndex = -1000;
+        value = timeNode.getValueFromList(values, largeNegativeIndex, shift);
+        assertEquals(2, value);
+        assertEquals(250, shift.get());
+    }
+
+    @Test
+    public void testGetValueFromListWithDuplicates() {
+        final List<Integer> tradingTimes = Arrays.asList(930, 930, 1130, 1130, 1300, 1500);
+        final AtomicInteger shift = new AtomicInteger(0);
+        int nextSession = timeNode.getValueFromList(tradingTimes, 10, shift);
+        assertEquals(1300, nextSession);
+        assertEquals(1, shift.get());
+
+        shift.set(0);
+        int prevSession = timeNode.getValueFromList(tradingTimes, -5, shift);
+        assertEquals(930, prevSession);
+        assertEquals(1, shift.get());
+    }
+
     private void assertResult(final int value, final int shift, final NearestValue nearestValue) {
         assertEquals(value, nearestValue.getValue(), String.format("Values do not match! Expected: %s Found: %s", value, nearestValue.getValue()));
         assertEquals(shift, nearestValue.getShifts(), String.format("Shifts do not match! Expected: %s Found: %s", shift, nearestValue.getShifts()));