diff --git a/tests/PhpSpreadsheetTests/Calculation/TextDataTest.php b/tests/PhpSpreadsheetTests/Calculation/TextDataTest.php
index b539abba..8b5d0218 100644
--- a/tests/PhpSpreadsheetTests/Calculation/TextDataTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/TextDataTest.php
@@ -323,9 +323,9 @@ class TextDataTest extends \PHPUnit_Framework_TestCase
     public function testTEXT()
     {
         //    Enforce decimal and thousands separator values to UK/US, and currency code to USD
-        call_user_func([StringHelper::class, 'setDecimalSeparator'], '.');
-        call_user_func([StringHelper::class, 'setThousandsSeparator'], ',');
-        call_user_func([StringHelper::class, 'setCurrencyCode'], '$');
+        StringHelper::setDecimalSeparator('.');
+        StringHelper::setThousandsSeparator(',');
+        StringHelper::setCurrencyCode('$');
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -343,9 +343,9 @@ class TextDataTest extends \PHPUnit_Framework_TestCase
      */
     public function testVALUE()
     {
-        call_user_func([StringHelper::class, 'setDecimalSeparator'], '.');
-        call_user_func([StringHelper::class, 'setThousandsSeparator'], ' ');
-        call_user_func([StringHelper::class, 'setCurrencyCode'], '$');
+        StringHelper::setDecimalSeparator('.');
+        StringHelper::setThousandsSeparator(' ');
+        StringHelper::setCurrencyCode('$');
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
diff --git a/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php b/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
index f0fb0aff..8fced6da 100644
--- a/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
@@ -16,7 +16,7 @@ class DataTypeTest extends \PHPUnit_Framework_TestCase
 
     public function testGetErrorCodes()
     {
-        $result = call_user_func([DataType::class, 'getErrorCodes']);
+        $result = DataType::getErrorCodes();
         $this->assertInternalType('array', $result);
         $this->assertGreaterThan(0, count($result));
         $this->assertArrayHasKey('#NULL!', $result);
diff --git a/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php b/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
index 38a3629b..c1cd9aae 100644
--- a/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
@@ -81,7 +81,7 @@ class DefaultValueBinderTest extends \PHPUnit_Framework_TestCase
         $objRichText->createText('Hello World');
 
         $expectedResult = DataType::TYPE_INLINE;
-        $result = call_user_func([DefaultValueBinder::class, 'dataTypeForValue'], $objRichText);
+        $result = DefaultValueBinder::dataTypeForValue($objRichText);
         $this->assertEquals($expectedResult, $result);
     }
 }
diff --git a/tests/PhpSpreadsheetTests/CellTest.php b/tests/PhpSpreadsheetTests/CellTest.php
index 7ad5e8bf..995d2926 100644
--- a/tests/PhpSpreadsheetTests/CellTest.php
+++ b/tests/PhpSpreadsheetTests/CellTest.php
@@ -27,7 +27,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = 'ABCD';
         try {
-            call_user_func([Cell::class, 'columnIndexFromString'], $cellAddress);
+            Cell::columnIndexFromString($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Column string index can not be longer than 3 characters');
@@ -41,7 +41,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = '';
         try {
-            call_user_func([Cell::class, 'columnIndexFromString'], $cellAddress);
+            Cell::columnIndexFromString($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Column string index can not be empty');
@@ -87,7 +87,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = 'A1:AI2012';
         try {
-            call_user_func([Cell::class, 'coordinateFromString'], $cellAddress);
+            Cell::coordinateFromString($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Cell coordinate string can not be a range of cells');
@@ -101,7 +101,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = '';
         try {
-            call_user_func([Cell::class, 'coordinateFromString'], $cellAddress);
+            Cell::coordinateFromString($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Cell coordinate can not be zero-length string');
@@ -115,7 +115,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = 'AI';
         try {
-            call_user_func([Cell::class, 'coordinateFromString'], $cellAddress);
+            Cell::coordinateFromString($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Invalid cell coordinate ' . $cellAddress);
@@ -145,7 +145,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = 'A1:AI2012';
         try {
-            call_user_func([Cell::class, 'absoluteCoordinate'], $cellAddress);
+            Cell::absoluteCoordinate($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Cell coordinate string can not be a range of cells');
@@ -175,7 +175,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellAddress = 'A1:AI2012';
         try {
-            call_user_func([Cell::class, 'absoluteReference'], $cellAddress);
+            Cell::absoluteReference($cellAddress);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Cell coordinate string can not be a range of cells');
@@ -227,7 +227,7 @@ class CellTest extends \PHPUnit_Framework_TestCase
     {
         $cellRange = '';
         try {
-            call_user_func([Cell::class, 'buildRange'], $cellRange);
+            Cell::buildRange($cellRange);
         } catch (\Exception $e) {
             $this->assertInstanceOf(Exception::class, $e);
             $this->assertEquals($e->getMessage(), 'Range does not contain any information');
diff --git a/tests/PhpSpreadsheetTests/SettingsTest.php b/tests/PhpSpreadsheetTests/SettingsTest.php
index 4a3c5fa5..4712f206 100644
--- a/tests/PhpSpreadsheetTests/SettingsTest.php
+++ b/tests/PhpSpreadsheetTests/SettingsTest.php
@@ -12,7 +12,7 @@ class SettingsTest extends \PHPUnit_Framework_TestCase
      */
     public function testGetXMLSettings()
     {
-        $result = call_user_func([\PhpSpreadsheet\Settings::class, 'getLibXmlLoaderOptions']);
+        $result = \PhpSpreadsheet\Settings::getLibXmlLoaderOptions();
         $this->assertTrue((bool) ((LIBXML_DTDLOAD | LIBXML_DTDATTR) & $result));
     }
 
@@ -21,7 +21,7 @@ class SettingsTest extends \PHPUnit_Framework_TestCase
     public function testSetXMLSettings()
     {
         call_user_func_array([\PhpSpreadsheet\Settings::class, 'setLibXmlLoaderOptions'], [LIBXML_DTDLOAD | LIBXML_DTDATTR | LIBXML_DTDVALID]);
-        $result = call_user_func([\PhpSpreadsheet\Settings::class, 'getLibXmlLoaderOptions']);
+        $result = \PhpSpreadsheet\Settings::getLibXmlLoaderOptions();
         $this->assertTrue((bool) ((LIBXML_DTDLOAD | LIBXML_DTDATTR | LIBXML_DTDVALID) & $result));
     }
 }
diff --git a/tests/PhpSpreadsheetTests/Shared/CodePageTest.php b/tests/PhpSpreadsheetTests/Shared/CodePageTest.php
index 10f93449..7376a97c 100644
--- a/tests/PhpSpreadsheetTests/Shared/CodePageTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/CodePageTest.php
@@ -27,7 +27,7 @@ class CodePageTest extends \PHPUnit_Framework_TestCase
     {
         $invalidCodePage = 12345;
         try {
-            call_user_func([CodePage::class, 'numberToName'], $invalidCodePage);
+            CodePage::numberToName($invalidCodePage);
         } catch (Exception $e) {
             $this->assertEquals($e->getMessage(), 'Unknown codepage: 12345');
 
@@ -40,7 +40,7 @@ class CodePageTest extends \PHPUnit_Framework_TestCase
     {
         $unsupportedCodePage = 720;
         try {
-            call_user_func([CodePage::class, 'numberToName'], $unsupportedCodePage);
+            CodePage::numberToName($unsupportedCodePage);
         } catch (Exception $e) {
             $this->assertEquals($e->getMessage(), 'Code page 720 not supported.');
 
diff --git a/tests/PhpSpreadsheetTests/Shared/DateTest.php b/tests/PhpSpreadsheetTests/Shared/DateTest.php
index ea0182e7..6b8f5741 100644
--- a/tests/PhpSpreadsheetTests/Shared/DateTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/DateTest.php
@@ -14,7 +14,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
         ];
 
         foreach ($calendarValues as $calendarValue) {
-            $result = call_user_func([Date::class, 'setExcelCalendar'], $calendarValue);
+            $result = Date::setExcelCalendar($calendarValue);
             $this->assertTrue($result);
         }
     }
@@ -22,7 +22,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
     public function testSetExcelCalendarWithInvalidValue()
     {
         $unsupportedCalendar = '2012';
-        $result = call_user_func([Date::class, 'setExcelCalendar'], $unsupportedCalendar);
+        $result = Date::setExcelCalendar($unsupportedCalendar);
         $this->assertFalse($result);
     }
 
@@ -31,10 +31,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeExcelToTimestamp1900()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_WINDOWS_1900
-        );
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -52,10 +49,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeTimestampToExcel1900()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_WINDOWS_1900
-        );
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -73,10 +67,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeDateTimeToExcel()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_WINDOWS_1900
-        );
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -94,10 +85,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeFormattedPHPToExcel1900()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_WINDOWS_1900
-        );
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -115,10 +103,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeExcelToTimestamp1904()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_MAC_1904
-        );
+        Date::setExcelCalendar(Date::CALENDAR_MAC_1904);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -136,10 +121,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeTimestampToExcel1904()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_MAC_1904
-        );
+        Date::setExcelCalendar(Date::CALENDAR_MAC_1904);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
@@ -173,10 +155,7 @@ class DateTest extends \PHPUnit_Framework_TestCase
      */
     public function testDateTimeExcelToTimestamp1900Timezone()
     {
-        call_user_func(
-            [Date::class, 'setExcelCalendar'],
-            Date::CALENDAR_WINDOWS_1900
-        );
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $args = func_get_args();
         $expectedResult = array_pop($args);
diff --git a/tests/PhpSpreadsheetTests/Shared/FileTest.php b/tests/PhpSpreadsheetTests/Shared/FileTest.php
index 61bc9729..cc05a6f6 100644
--- a/tests/PhpSpreadsheetTests/Shared/FileTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/FileTest.php
@@ -10,7 +10,7 @@ class FileTest extends \PHPUnit_Framework_TestCase
     {
         $expectedResult = false;
 
-        $result = call_user_func([File::class, 'getUseUploadTempDirectory']);
+        $result = File::getUseUploadTempDirectory();
         $this->assertEquals($expectedResult, $result);
     }
 
@@ -22,9 +22,9 @@ class FileTest extends \PHPUnit_Framework_TestCase
         ];
 
         foreach ($useUploadTempDirectoryValues as $useUploadTempDirectoryValue) {
-            call_user_func([File::class, 'setUseUploadTempDirectory'], $useUploadTempDirectoryValue);
+            File::setUseUploadTempDirectory($useUploadTempDirectoryValue);
 
-            $result = call_user_func([File::class, 'getUseUploadTempDirectory']);
+            $result = File::getUseUploadTempDirectory();
             $this->assertEquals($useUploadTempDirectoryValue, $result);
         }
     }
diff --git a/tests/PhpSpreadsheetTests/Shared/FontTest.php b/tests/PhpSpreadsheetTests/Shared/FontTest.php
index 8a93425f..e50a3f15 100644
--- a/tests/PhpSpreadsheetTests/Shared/FontTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/FontTest.php
@@ -10,7 +10,7 @@ class FontTest extends \PHPUnit_Framework_TestCase
     {
         $expectedResult = Font::AUTOSIZE_METHOD_APPROX;
 
-        $result = call_user_func([Font::class, 'getAutoSizeMethod']);
+        $result = Font::getAutoSizeMethod();
         $this->assertEquals($expectedResult, $result);
     }
 
@@ -22,7 +22,7 @@ class FontTest extends \PHPUnit_Framework_TestCase
         ];
 
         foreach ($autosizeMethodValues as $autosizeMethodValue) {
-            $result = call_user_func([Font::class, 'setAutoSizeMethod'], $autosizeMethodValue);
+            $result = Font::setAutoSizeMethod($autosizeMethodValue);
             $this->assertTrue($result);
         }
     }
@@ -31,7 +31,7 @@ class FontTest extends \PHPUnit_Framework_TestCase
     {
         $unsupportedAutosizeMethod = 'guess';
 
-        $result = call_user_func([Font::class, 'setAutoSizeMethod'], $unsupportedAutosizeMethod);
+        $result = Font::setAutoSizeMethod($unsupportedAutosizeMethod);
         $this->assertFalse($result);
     }
 
diff --git a/tests/PhpSpreadsheetTests/Shared/StringTest.php b/tests/PhpSpreadsheetTests/Shared/StringTest.php
index 8accc643..4fe28bc1 100644
--- a/tests/PhpSpreadsheetTests/Shared/StringTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/StringTest.php
@@ -11,18 +11,18 @@ class StringTest extends \PHPUnit_Framework_TestCase
         parent::setUp();
 
         // Reset Currency Code
-        call_user_func([StringHelper::class, 'setCurrencyCode'], null);
+        StringHelper::setCurrencyCode(null);
     }
 
     public function testGetIsMbStringEnabled()
     {
-        $result = call_user_func([StringHelper::class, 'getIsMbstringEnabled']);
+        $result = StringHelper::getIsMbstringEnabled();
         $this->assertTrue($result);
     }
 
     public function testGetIsIconvEnabled()
     {
-        $result = call_user_func([StringHelper::class, 'getIsIconvEnabled']);
+        $result = StringHelper::getIsIconvEnabled();
         $this->assertTrue($result);
     }
 
@@ -31,16 +31,16 @@ class StringTest extends \PHPUnit_Framework_TestCase
         $localeconv = localeconv();
 
         $expectedResult = (!empty($localeconv['decimal_point'])) ? $localeconv['decimal_point'] : ',';
-        $result = call_user_func([StringHelper::class, 'getDecimalSeparator']);
+        $result = StringHelper::getDecimalSeparator();
         $this->assertEquals($expectedResult, $result);
     }
 
     public function testSetDecimalSeparator()
     {
         $expectedResult = ',';
-        call_user_func([StringHelper::class, 'setDecimalSeparator'], $expectedResult);
+        StringHelper::setDecimalSeparator($expectedResult);
 
-        $result = call_user_func([StringHelper::class, 'getDecimalSeparator']);
+        $result = StringHelper::getDecimalSeparator();
         $this->assertEquals($expectedResult, $result);
     }
 
@@ -49,16 +49,16 @@ class StringTest extends \PHPUnit_Framework_TestCase
         $localeconv = localeconv();
 
         $expectedResult = (!empty($localeconv['thousands_sep'])) ? $localeconv['thousands_sep'] : ',';
-        $result = call_user_func([StringHelper::class, 'getThousandsSeparator']);
+        $result = StringHelper::getThousandsSeparator();
         $this->assertEquals($expectedResult, $result);
     }
 
     public function testSetThousandsSeparator()
     {
         $expectedResult = ' ';
-        call_user_func([StringHelper::class, 'setThousandsSeparator'], $expectedResult);
+        StringHelper::setThousandsSeparator($expectedResult);
 
-        $result = call_user_func([StringHelper::class, 'getThousandsSeparator']);
+        $result = StringHelper::getThousandsSeparator();
         $this->assertEquals($expectedResult, $result);
     }
 
@@ -66,16 +66,16 @@ class StringTest extends \PHPUnit_Framework_TestCase
     {
         $localeconv = localeconv();
         $expectedResult = (!empty($localeconv['currency_symbol']) ? $localeconv['currency_symbol'] : (!empty($localeconv['int_curr_symbol']) ? $localeconv['int_curr_symbol']: '$'));
-        $result = call_user_func([StringHelper::class, 'getCurrencyCode']);
+        $result = StringHelper::getCurrencyCode();
         $this->assertEquals($expectedResult, $result);
     }
 
     public function testSetCurrencyCode()
     {
         $expectedResult = '£';
-        call_user_func([StringHelper::class, 'setCurrencyCode'], $expectedResult);
+        StringHelper::setCurrencyCode($expectedResult);
 
-        $result = call_user_func([StringHelper::class, 'getCurrencyCode']);
+        $result = StringHelper::getCurrencyCode();
         $this->assertEquals($expectedResult, $result);
     }
 }
diff --git a/tests/PhpSpreadsheetTests/Shared/TimeZoneTest.php b/tests/PhpSpreadsheetTests/Shared/TimeZoneTest.php
index 3b6d05e5..5483e730 100644
--- a/tests/PhpSpreadsheetTests/Shared/TimeZoneTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/TimeZoneTest.php
@@ -17,7 +17,7 @@ class TimeZoneTest extends \PHPUnit_Framework_TestCase
         ];
 
         foreach ($timezoneValues as $timezoneValue) {
-            $result = call_user_func([TimeZone::class, 'setTimezone'], $timezoneValue);
+            $result = TimeZone::setTimezone($timezoneValue);
             $this->assertTrue($result);
         }
     }
@@ -25,7 +25,7 @@ class TimeZoneTest extends \PHPUnit_Framework_TestCase
     public function testSetTimezoneWithInvalidValue()
     {
         $unsupportedTimezone = 'Etc/GMT+10';
-        $result = call_user_func([TimeZone::class, 'setTimezone'], $unsupportedTimezone);
+        $result = TimeZone::setTimezone($unsupportedTimezone);
         $this->assertFalse($result);
     }
 }