Allow setting fill colour for bar chart data points

[DanWin]

This is:

• a bugfix
• a new feature

Checklist:

• Changes are covered by unit tests
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change
• Documentation is updated as necessary

Why this change is needed?

This will fix #1400 #1433 and #2183

[MarkBaker]

Thank you for this contribution.

Is it possible to provide some unit tests to verify this for all chart types that are affected? Charts is one area that is the least covered by tests, and it really needs some TLC there.

[MarkBaker]

in_array() should always be used in strict mode

[MarkBaker]

Please address requested change; and unit testing

[DanWin]

Agreed, in_array() should be in strict mode. I saw it mostly being non-strict in other parts of the code and the previous checks were also non-strict and thus kept it the same way.
As for unit testing, I'll need help with that. I've never written those and I'm not sure how to write tests for this case.

[MarkBaker]

Agreed, in_array() should be in strict mode. I saw it mostly being non-strict in other parts of the code and the previous checks were also non-strict and thus kept it the same way.

Thanks. A lot of the code that uses in_array() was originally written for earlier versions of PHP, before the strict mode flag was added. Now, we always try to apply it when we're working on those parts of the codebase where it isn't yet applied (scouting rules).

As for unit testing, I'll need help with that. I've never written those and I'm not sure how to write tests for this case.

There's some examples on how to approach testing in /tests/PhpSpreadsheetTests/Writer/Xlsx/* where we use the writer calls to return the XML to the test rather than actually saving to a file; and can then assert that the XML contains the markup that's expected.
e.g. ConditionalTest.php and the testWriteSimpleCellConditionalFromWizard() method.

Though you might want to create a Charts subfolder under .../Writer/Xlsx/, and put the test in there.

Something like:

namespace PhpOffice\PhpSpreadsheetTests\Writer\Xlsx\Charts;

use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;

class BarChartTest extends AbstractFunctional
{
    public function testWriteBarChartWithUserDefinedFillColors(): void
    {
        $spreadsheet = new Spreadsheet();
        $worksheet = $spreadsheet->getActiveSheet();

        // Code to create a bar chart with user-defined fill colours goes here

        $writer = new Xlsx($spreadsheet);
        $writerWorksheet = new Xlsx\Worksheet($writer);
        $data = $writerWorksheet->writeWorksheet($worksheet, []);

        $expected = <<<XML
//xml for a bar chart with user-defined fill colours goes here
XML;
        self::assertStringContainsString($expected, $data);
    }
}

[oleibman]

This PR will be superseded by #2906, including tests. Converting this to draft; and will close it if 2906 is merged.

[oleibman]

Superseded by 2906, which was just merged.