adding merge cell logic processing

formatting commit

addressing testcase failures

adding one more scenario to case

adding one more scenario to case

Adding update and unmerge functions for merge cell handling

adding one more case to testcase

adding testcases to base code

adding testcase for import/export

adding documentation to some of the PUB function

fixing warnings and test warnings

adding merge cell part cell update restriction to public sytle set fns

addressing reviwers comment : Changed Mergedcell structure and its side effercts

reverting it back to non pub.

renaming update_merge_cells to just merge_cells in model

renaming *unmerge_merged_cell* to *unmerge_cells*

addressing other reviewer's comment + cosmetica naming adjustments

cosmetic changes

xlsx/tests/test.rs

@@ -406,7 +406,7 @@ fn test_exporting_merged_cells() {
             .worksheets
             .first()
             .unwrap()
-            .merge_cells
+            .merged_cells_list
             .clone();
         // exporting and saving it in another xlsx
         model.evaluate();
@@ -423,7 +423,7 @@ fn test_exporting_merged_cells() {
                 .worksheets
                 .first()
                 .unwrap()
-                .merge_cells
+                .merged_cells_list
                 .clone();
             assert_eq!(expected_merge_cell_ref, *got_merge_cell_ref);
             fs::remove_file(temp_file_name).unwrap();
@@ -437,7 +437,7 @@ fn test_exporting_merged_cells() {
                 .worksheets
                 .get_mut(0)
                 .unwrap()
-                .merge_cells
+                .merged_cells_list
                 .clear();
 
             save_to_xlsx(&temp_model, temp_file_name).unwrap();
@@ -447,7 +447,7 @@ fn test_exporting_merged_cells() {
                 .worksheets
                 .first()
                 .unwrap()
-                .merge_cells
+                .merged_cells_list
                 .len();
             assert!(*got_merge_cell_ref_cnt == 0);
         }
@@ -494,3 +494,73 @@ fn test_documentation_xlsx() {
     }
     fs::remove_dir_all(&dir).unwrap();
 }
+
+#[test]
+fn test_merge_cell_import_export_behaviors() {
+    // loading the xlsx file containing merged cells
+    let example_file_name = "tests/Merged_cells.xlsx";
+    let mut model = load_from_xlsx(example_file_name, "en", "UTC").unwrap();
+
+    // Case1 : To check whether Merge cells structures got imported properly or not
+    let imported_merge_cell_vec = model.workbook.worksheet(0).unwrap().get_merged_cells_list();
+
+    assert_eq!(imported_merge_cell_vec.len(), 5);
+    let range_refs_of_merge_cell: Vec<String> = imported_merge_cell_vec
+        .iter()
+        .map(|cell| cell.get_merged_cells_str_ref().unwrap())
+        .collect();
+    assert_eq!(
+        range_refs_of_merge_cell,
+        [
+            "C1:D3".to_string(),
+            "A1:B4".to_string(),
+            "G1:H7".to_string(),
+            "D8:E9".to_string(),
+            "D4:F6".to_string()
+        ]
+    );
+
+    // Create one More Merge cell which Overlaps with 3 More
+    model.merge_cells(0, "A1:D5").unwrap();
+    model
+        .set_user_input(0, 1, 1, "New overlapped Merge cell".to_string())
+        .unwrap();
+
+    let mut style = model.get_style_for_cell(0, 1, 1).unwrap();
+    style.font.b = true;
+    assert_eq!(
+        model.workbook.styles.create_named_style("bold", &style),
+        Ok(())
+    );
+
+    model.set_cell_style_by_name(0, 1, 1, "bold").unwrap();
+
+    // Lets export to different Excell
+    let exported_merge_cell_xlsx = "temporary_exported_mergecells.xlsx";
+    save_to_xlsx(&model, exported_merge_cell_xlsx).unwrap();
+
+    {
+        let temp_model = load_from_xlsx(exported_merge_cell_xlsx, "en", "UTC").unwrap();
+        // Loading the exported sheet back and verifying whether it got exported properly or not
+        let imported_merge_cell_vec = temp_model
+            .workbook
+            .worksheet(0)
+            .unwrap()
+            .get_merged_cells_list();
+
+        assert_eq!(imported_merge_cell_vec.len(), 3);
+        let range_refs_of_merge_cell: Vec<String> = imported_merge_cell_vec
+            .iter()
+            .map(|cell| cell.get_merged_cells_str_ref().unwrap())
+            .collect();
+        assert_eq!(
+            range_refs_of_merge_cell,
+            [
+                "G1:H7".to_string(),
+                "D8:E9".to_string(),
+                "A1:D5".to_string()
+            ]
+        );
+    }
+    fs::remove_file(exported_merge_cell_xlsx).unwrap();
+}