Yield empty self-closing row tags as empty row during query. (#673)

src/MiniExcel/OpenXml/ExcelOpenXmlSheetReader.cs

@@ -277,7 +277,11 @@ namespace MiniExcelLibs.OpenXml
 
                                 // row -> c
                                 if (!XmlReaderHelper.ReadFirstContent(reader))
+                                {
+                                    //Fill in case of self closed empty row tag eg. <row r="1"/>
+                                    yield return GetCell(useHeaderRow, maxColumnIndex, headRows, startColumnIndex); 
                                     continue;
+                                }
 
                                 // startcell pass rows
                                 if (rowIndex < startRowIndex)

tests/MiniExcelTests/MiniExcelOpenXmlTests.cs

@@ -252,6 +252,27 @@ namespace MiniExcelLibs.Tests
             }
         }
 
+        [Fact]
+        public void TestEmptyRowsQuerySelfClosingTag()
+        {
+            var path = @"../../../../../samples/xlsx/TestEmptySelfClosingRow.xlsx";
+            using (var stream = File.OpenRead(path))
+            {
+                var rows = stream.Query().ToList();
+
+                Assert.Equal(null, rows[0].A);
+                Assert.Equal(1, rows[1].A);
+                Assert.Equal(null, rows[2].A);
+                Assert.Equal(2, rows[3].A);
+                Assert.Equal(null, rows[4].A);
+                Assert.Equal(null, rows[5].A);
+                Assert.Equal(null, rows[6].A);
+                Assert.Equal(null, rows[7].A);
+                Assert.Equal(null, rows[8].A);
+                Assert.Equal(1, rows[9].A);
+            }
+        }
+
         [Fact()]
         public void TestDynamicQueryBasic_WithoutHead()
         {