Fix 337 : Reader\Csv::inferSeparator() generates a notice when the file is empty

phpunit.xml.dist

@@ -5,6 +5,7 @@
     syntaxCheck="true"
     disallowTestOutput="true">
     <php>
+        <ini name="error_reporting" value="-1"/>
         <ini name="memory_limit" value="2048M"/>
     </php>
     <testsuite name="PhpSpreadsheet Unit Test Suite">

src/PhpSpreadsheet/Reader/Csv.php

@@ -181,6 +181,13 @@ protected function inferSeparator()
             }
         }
 
+        // If number of lines is 0, nothing to infer : fall back to the default
+        if ($numberLines === 0) {
+            $this->delimiter = reset($potentialDelimiters);
+
+            return $this->skipBOM();
+        }
+
         // Calculate the mean square deviations for each delimiter (ignoring delimiters that haven't been found consistently)
         $meanSquareDeviations = [];
         $middleIdx = floor(($numberLines - 1) / 2);

tests/PhpSpreadsheetTests/Reader/CsvTest.php

@@ -67,6 +67,18 @@ public function providerDelimiterDetection()
                 'D8',
                 -58.373161,
             ],
+            [
+                'data/Reader/CSV/empty.csv',
+                ',',
+                'A1',
+                null,
+            ],
+            [
+                'data/Reader/CSV/no_delimiter.csv',
+                ',',
+                'A1',
+                'SingleLine',
+            ],
         ];
     }
 

tests/data/Reader/CSV/no_delimiter.csv

@@ -0,0 +1 @@
+SingleLine