Fixed Functions->ifCondition for allowing <> and empty condition

In cells with formulas containing conditions like `=IFSUM(A1:A3;"";B1:B3)`
to sum cells from range A1:A3 with empty value in range B1:B3, the function
`Functions::ifCondition()` create in this case the code `=""""` instead of
`=""`, so it didn't work.

Closes #1206

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Keep big integer as integer instead of lossely casting to float [#874](https://github.com/PHPOffice/PhpSpreadsheet/pull/874)
 - Fix branch pruning handling of non boolean conditions [#1167](https://github.com/PHPOffice/PhpSpreadsheet/pull/1167)
 - Fix ODS Reader when no DC namespace are defined [#1182](https://github.com/PHPOffice/PhpSpreadsheet/pull/1182)
+- Fixed Functions->ifCondition for allowing <> and empty condition [#1206](https://github.com/PHPOffice/PhpSpreadsheet/pull/1206)
 
 ## [1.9.0] - 2019-08-17
 

src/PhpSpreadsheet/Calculation/Functions.php

@@ -278,7 +278,7 @@ class Functions
                 $condition = Calculation::wrapResult(strtoupper($condition));
             }
 
-            return '=' . $condition;
+            return str_replace('""""', '""', '=' . $condition);
         }
         preg_match('/(=|<[>=]?|>=?)(.*)/', $condition, $matches);
         [, $operator, $operand] = $matches;
@@ -290,7 +290,7 @@ class Functions
             $operand = Calculation::wrapResult(strtoupper($operand));
         }
 
-        return $operator . $operand;
+        return str_replace('""""', '""', $operator . $operand);
     }
 
     /**

tests/data/Calculation/Functions/IF_CONDITION.php

@@ -33,4 +33,12 @@ return [
         '<>"< PLEASE SELECT >"',
         '<>< Please Select >',
     ],
+    [
+        '<>""',
+        '<>',
+    ],
+    [
+        '=""',
+        '""',
+    ],
 ];