- Create unit test (#944)

- Add changelog entry for issue #700

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 - Fix handling for escaped enclosures and new lines in CSV Separator Inference
 - Fix MATCH an error was appearing when comparing strings against 0 (always true)
+- Fix wrong calculation of highest column with specified row [#700](https://github.com/PHPOffice/PhpSpreadsheet/issues/700)
 - Fix VLOOKUP 
 - Fix return type hint
 

tests/PhpSpreadsheetTests/Collection/CellsTest.php

@@ -114,4 +114,21 @@ class CellsTest extends TestCase
         $collection->add('A1', $cell);
         $collection->add('A2', $cell);
     }
+
+    public function testGetHighestColumn()
+    {
+        $workbook = new Spreadsheet();
+        $sheet = $workbook->getActiveSheet();
+        $collection = $sheet->getCellCollection();
+
+        // check for empty sheet
+        $this->assertEquals('A', $collection->getHighestColumn());
+        $this->assertEquals('A', $collection->getHighestColumn(1));
+
+        // set a value and check again
+        $sheet->getCell('C4')->setValue(1);
+        $this->assertEquals('C', $collection->getHighestColumn());
+        $this->assertEquals('A', $collection->getHighestColumn(1));
+        $this->assertEquals('C', $collection->getHighestColumn(4));
+    }
 }