Exporting the Merged Cell : Exports the merged cell properly with testcase to verify the scenario (#76)

* adding the functionality of exporting the merged cell with testcase to vreify the above enhancement

* addressing review comments : 1) moving the testing to appropriate folder 2) fixing lint errors 3) fixing the scenario when merge cell count is 0

* addressing 2nd round review comments : cosmetic fixes

* addressing review comments : taking reference instead of cloning

xlsx/src/export/worksheets.rs

@@ -59,6 +59,7 @@ pub(crate) fn get_worksheet_xml(
 ) -> String {
     let mut sheet_data_str: Vec<String> = vec![];
     let mut cols_str: Vec<String> = vec![];
+    let mut merged_cells_str: Vec<String> = vec![];
 
     for col in &worksheet.cols {
         // <col min="4" max="4" width="12" customWidth="1"/>
@@ -241,6 +242,12 @@ pub(crate) fn get_worksheet_xml(
         ))
     }
     let sheet_data = sheet_data_str.join("");
+
+    for merge_cell_ref in &worksheet.merge_cells {
+        merged_cells_str.push(format!("<mergeCell ref=\"{merge_cell_ref}\"/>"))
+    }
+    let merged_cells_count = merged_cells_str.len();
+
     let cols = cols_str.join("");
     let cols = if cols.is_empty() {
         "".to_string()
@@ -280,6 +287,16 @@ pub(crate) fn get_worksheet_xml(
         }
     }
 
+    let merge_cells_section = if merged_cells_count > 0 {
+        format!(
+            "<mergeCells count=\"{}\">{}</mergeCells>",
+            merged_cells_count,
+            merged_cells_str.join("")
+        )
+    } else {
+        "".to_string()
+    };
+
     format!(
         "{XML_DECLARATION}
 <worksheet \
@@ -295,6 +312,7 @@ xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\">
   <sheetData>\
   {sheet_data}\
   </sheetData>\
+  {merge_cells_section}\
 </worksheet>"
     )
 }

xlsx/tests/test.rs

@@ -334,3 +334,68 @@ fn no_export() {
     }
     fs::remove_dir_all(&dir).unwrap();
 }
+
+// This test verifies whether exporting the merged cells functionality is happening properly or not.
+// It first loads the excell having the merged cell and exports it to another xlsx and verifies whether merged
+// cell node is same in both of the xlsx file or not.
+#[test]
+fn test_exporting_merged_cells() {
+    let temp_file_name = "temp_file_test_export_merged_cells.xlsx";
+    let expected_merge_cell_ref = {
+        // loading the xlsx file containing merged cells
+        let example_file_name = "tests/example.xlsx";
+        let mut model = load_from_xlsx(example_file_name, "en", "UTC").unwrap();
+        let expected_merge_cell_ref = model
+            .workbook
+            .worksheets
+            .first()
+            .unwrap()
+            .merge_cells
+            .clone();
+        // exporting and saving it in another xlsx
+        model.evaluate();
+        save_to_xlsx(&model, temp_file_name).unwrap();
+        expected_merge_cell_ref
+    };
+    {
+        let mut temp_model = load_from_xlsx(temp_file_name, "en", "UTC").unwrap();
+        {
+            // loading the previous file back and verifying whether
+            // merged cells got exported properly or not
+            let got_merge_cell_ref = &temp_model
+                .workbook
+                .worksheets
+                .first()
+                .unwrap()
+                .merge_cells
+                .clone();
+            assert_eq!(expected_merge_cell_ref, *got_merge_cell_ref);
+            fs::remove_file(temp_file_name).unwrap();
+        }
+        {
+            // this block is to verify that if there are no
+            // merged cells, exported xml should not have the
+            // <mergeCells/> xml node
+            temp_model
+                .workbook
+                .worksheets
+                .get_mut(0)
+                .unwrap()
+                .merge_cells
+                .clear();
+
+            save_to_xlsx(&temp_model, temp_file_name).unwrap();
+            let temp_model2 = load_from_xlsx(temp_file_name, "en", "UTC").unwrap();
+            let got_merge_cell_ref_cnt = &temp_model2
+                .workbook
+                .worksheets
+                .first()
+                .unwrap()
+                .merge_cells
+                .len();
+            assert!(*got_merge_cell_ref_cnt == 0);
+        }
+    }
+
+    fs::remove_file(temp_file_name).unwrap();
+}