Create PHPUnit test cases for server code

[bobbingwide]

Some not insignificant changes are currently being developed. It's about time we implemented some regression testing capability for the PHP code.

Requirements

• Regression testing capability for PHP code.
• Tests to cover expected settings for each attribute.
• Tests to cover good and bad CSV data for the chart.
• Tests to be developed before any new solutions are merged.

Proposed solution

• Develop In Situ PHPUnit tests similar to those for other plugins oik plugins that deliver shortcodes / blocks.
• But no need to implement tests for internationalization.
• Generated .html test results files should be easy to validate against ChartJS.

[misaki-web]

We may also have a boolean constant (like SB_CHART_BLOCK_DEBUG) to deal with commented debug lines. Examples:

https://github.com/bobbingwide/sb-chart-block/blob/22ebbf178529f30d678e2c1d558a6660f2625386/libs/class-sb-chart-block.php#L78

https://github.com/bobbingwide/sb-chart-block/blob/22ebbf178529f30d678e2c1d558a6660f2625386/libs/class-sb-chart-block.php#L98

Something like this:

if ( SB_CHART_BLOCK_DEBUG ) print_r( $atts );

[bobbingwide]

Delivered in v1.2.0