Function EXACT(arg1, arg2) support (#595)

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- Add excel function EXACT(value1, value2) support
 - Support workbook view attributes for Xlsx format - [#523](https://github.com/PHPOffice/PhpSpreadsheet/issues/523)
 
 ### Fixed

src/PhpSpreadsheet/Calculation/Calculation.php

@@ -752,7 +752,7 @@ class Calculation
         ],
         'EXACT' => [
             'category' => Category::CATEGORY_TEXT_AND_DATA,
-            'functionCall' => [Functions::class, 'DUMMY'],
+            'functionCall' => [TextData::class, 'EXACT'],
             'argumentCount' => '2',
         ],
         'EXP' => [

src/PhpSpreadsheet/Calculation/TextData.php

@@ -577,4 +577,22 @@ public static function VALUE($value = '')
 
         return (float) $value;
     }
+
+    /**
+     * Compares two text strings and returns TRUE if they are exactly the same, FALSE otherwise.
+     * EXACT is case-sensitive but ignores formatting differences.
+     * Use EXACT to test text being entered into a document.
+     *
+     * @param $value1
+     * @param $value2
+     *
+     * @return bool
+     */
+    public static function EXACT($value1, $value2)
+    {
+        $value1 = Functions::flattenSingleValue($value1);
+        $value2 = Functions::flattenSingleValue($value2);
+
+        return (string) $value2 === (string) $value1;
+    }
 }

tests/PhpSpreadsheetTests/Calculation/TextDataTest.php

@@ -359,4 +359,28 @@ public function providerVALUE()
     {
         return require 'data/Calculation/TextData/VALUE.php';
     }
+
+    /**
+     * @dataProvider providerEXACT
+     *
+     * @param mixed $expectedResult
+     * @param array $args
+     */
+    public function testEXACT($expectedResult, ...$args)
+    {
+        StringHelper::setDecimalSeparator('.');
+        StringHelper::setThousandsSeparator(' ');
+        StringHelper::setCurrencyCode('$');
+
+        $result = TextData::EXACT(...$args);
+        self::assertSame($expectedResult, $result, null);
+    }
+
+    /**
+     * @return array
+     */
+    public function providerEXACT()
+    {
+        return require 'data/Calculation/TextData/EXACT.php';
+    }
 }

tests/data/Calculation/TextData/EXACT.php

@@ -0,0 +1,39 @@
+<?php
+
+return [
+    [
+        true,
+        '',
+        '',
+    ],
+    [
+        true,
+        '1000',
+        1000,
+    ],
+    [
+        true,
+        1000,
+        '1000',
+    ],
+    [
+        true,
+        'Abč',
+        'Abč',
+    ],
+    [
+        false,
+        'abč',
+        'Abč',
+    ],
+    [
+        false,
+        '10.010',
+        10.01,
+    ],
+    [
+        false,
+        '  ',
+        '',
+    ],
+];