Fix#3899. Supersedes PR #4476, which will be changed to draft status and closed if this PR is merged.
A standard cast from float to string in PHP can drop trailing decimal positions. This can lead to problems above and beyond the usual problems associated with floating point. See the superseded PR for a more complete explanation.
`StringHelper::convertToString` is changed for how it handles floats. It will now do separate casts for the whole and decimal parts, and then combine the results. This affects `Cell::getValueString` and `Cell::getCalculatedValueString`. Xlsx Writer will now invoke `convertToString` before writing a float to Xml. Ods Writer already uses `getValueString`, so no change is needed there. Xls Writer writes its float values in binary, so no change is needed there. Tests are added for all 3 writers.
Aside from fixing some problems, it might appear that this change introduces some new problems. For instance, setting a cell to `12345.6789` will now result in `12345.67890000000079` in the Xml. This difference is an illusion, merely a consequence of floating point rounding. If you run the following check under PhpUnit, it will pass:
```php
self::assertSame(12345.6789, 12345.67890000000079);
```
With PhpUnit 10 came the ability to use Php attributes rather than doc-block annotations for things like "data provider". PhpUnit 11 deprecates the use of annotations, and PhpUnit 12 will not not permit their use. Since PhpUnit 11 requires Php8.2+, we cannot adopt it as long as we support Php8.1, which will continue to be the case for some time. However, there is no penalty for early adoption.
Php-cs-fixer can use:
```
'php_unit_attributes' => ['keep_annotations' => false],
```
This allows us to run `composer fix` to automate all the needed changes. No manual changes were needed for any of the test members.
With this change, PhpUnit 9 can no longer be used with the test suite. File composer.json is updated to reflect that reality, and phpunit9.xml.dist, which has been supplied in case anyone needed to use PhpUnit 9, is no longer required, and is thus deleted. For now, PhpUnit 11 is not being added as a possibility.
No source code is changed in this PR.
While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
Successor to PR #3523. There are 494 single-line changes (`public function provider` to `public static function provider`) in this PR. None of these were made manually; they were all created with the following script (adapted from
https://stackoverflow.com/questions/25909820/how-to-recursively-iterate-through-files-in-php):
```php
$dir = 'C:/git/unit10prep2/tests/PhpSpreadsheetTests';
$it = new RecursiveDirectoryIterator($dir);
// Loop through files
foreach(new RecursiveIteratorIterator($it) as $file) {
if ($file->getExtension() === 'php') {
$contents = file_get_contents($file);
$new = preg_replace('/public function (\\w*)([Pp])rovider/', 'public static function $1$2rovider', $contents);
if ($new !== $contents) {
echo "changing $file\n";
file_put_contents($file, $new);
}
}
}
```
After this PR, there will be one more, with a small number of test changes, and enabling PhpUnit 10 for Php 8.1+.