add XmlReportPage tests

Author: vananiev

src/main/java/org/spacious_team/table_wrapper/xml/XmlReportPage.java

@@ -80,21 +80,21 @@ int findEmptyRow(int startRow, int endRow) {
         int lastRowNum = Math.max(0, startRow);
         for (int n = getLastRowNum(); lastRowNum <= n && lastRowNum < endRow; lastRowNum++) {
             Row row = sheet.getRowAt(lastRowNum + 1);
-            if (row == null || row.getCellMap().isEmpty()) {
-                return lastRowNum;  // all row cells blank
+            if (row == null || row.getCellMap() == null || row.getCellMap().isEmpty()) {
+                return lastRowNum;  // all row cells are blank
             }
             boolean isRowEmpty = true;
             for (@Nullable Cell cell : row.getCells()) {
                 @Nullable Object value;
                 if (!(cell == null
                         || ((value = XmlCellDataAccessObject.INSTANCE.getValue(cell)) == null)
-                        || (value instanceof String) && (value.toString().isEmpty()))) {
+                        || ((value instanceof String) && (value.toString().isEmpty())))) {
                     isRowEmpty = false;
                     break;
                 }
             }
             if (isRowEmpty) {
-                return lastRowNum;  // all row cells blank
+                return lastRowNum;  // all row cells are blank
             }
         }
         return -1;

src/test/java/org/spacious_team/table_wrapper/xml/XmlReportPageTest.java

@@ -118,6 +118,14 @@ void findEmptyRow_noEmpty() {
         assertEquals(-1, reportPage.findEmptyRow(0, Integer.MAX_VALUE));
     }
 
+    @Test
+    void findEmptyRow_limitEnd_noEmpty() {
+        Worksheet worksheet = getWorksheet();
+        XmlReportPage reportPage = new XmlReportPage(worksheet);
+
+        assertEquals(-1, reportPage.findEmptyRow(0, 1));
+    }
+
     @Test
     void findEmptyRow_onEmptySheet() {
         Worksheet worksheet = new SSWorksheet("test sheet");
@@ -136,7 +144,7 @@ void findEmptyRow_onSheetOfEmptyRow() {
     }
 
     @Test
-    void findEmptyRow() {
+    void findEmptyRow_allCellsAreEmpty() {
         Worksheet worksheet = getWorksheet();
         worksheet.addCellAt(3, 1).setData("");
         worksheet.addCellAt(3, 2).setData("");
@@ -145,11 +153,20 @@ void findEmptyRow() {
         assertEquals(2, reportPage.findEmptyRow(0, Integer.MAX_VALUE));
     }
 
+    @Test
+    void findEmptyRow_row2IsNull() {
+        Worksheet worksheet = getWorksheet();
+        worksheet.addCellAt(4, 1).setData("");  // zero based row num = 3, zero based row 2 now is null
+        XmlReportPage reportPage = new XmlReportPage(worksheet);
+
+        assertEquals(2, reportPage.findEmptyRow(0, Integer.MAX_VALUE));
+    }
+
     private static Worksheet getWorksheet() {
         Worksheet worksheet = new SSWorksheet("test sheet");
         worksheet.addCellAt(1, 1).setData("11");
         worksheet.addCellAt(1, 2).setData("12");
-        worksheet.addCellAt(2, 1).setData("21");
+        worksheet.addCellAt(2, 1).setData(21);
         worksheet.addCellAt(2, 2).setData("22");
         return worksheet;
     }