EDIT

<?php

// using namespace to allow for better sorting of test classes in the results

namespace test\phpunit\unit;

use PHPUnit\Framework\TestCase;

// these includes require <includePath>../..</includePath> to be set in phpUnit.xml

include 'includes/common.inc';

include 'cdm_api/commons.php';

/**

 * test to test if phpUnit is ok

 * @author a.kohlbecker

 *

 */

class StatisticalValuesTest extends TestCase {

  function new_statistical_value($value = null){

    $stat_val = new \stdClass(); // need to use the root namespace

    $stat_val->_value = $value;

    return $stat_val;

  }

  function create_statistical_values($typicalLowerBoundary = null, $typicalUpperrBoundary = null, $average  = null, $sampleSize = null, $variance = null, $standard_deviation = null){

    $stat_vals = statistical_values_array();

    $stat_vals['TypicalLowerBoundary'] = $this->new_statistical_value($typicalLowerBoundary);

    $stat_vals['TypicalUpperBoundary'] = $this->new_statistical_value($typicalUpperrBoundary);

    $stat_vals['SampleSize'] = $this->new_statistical_value($sampleSize);

    $stat_vals['Average'] = $this->new_statistical_value($average);

    if($variance){

      $stat_vals['Variance'] = $this->new_statistical_value($variance);

    }

    if($standard_deviation){

      $stat_vals['StandardDeviation'] = $this->new_statistical_value($standard_deviation);

    }

    return $stat_vals;

  }

  function html2text($html){

    return  html_entity_decode(strip_tags($html), ENT_COMPAT, 'utf-8');

  }

  function test_statistical_values_significant_figures_avarage() {

    $stat_vals = $this->create_statistical_values(0.123457,  0.123456, 0.123456523847, 5);

    $this->assertEquals('0.123457–0.123456 [5;x̄=0.1234565]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(12.23,  14.2, 13.2231423, 15);

    $this->assertEquals('12.23–14.2 [15;x̄=13.2]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(4,  6, 5, 2);

    $this->assertEquals('4–6 [2;x̄=5]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(4,  6, 5.0000, 2);

    $this->assertEquals('4–6 [2;x̄=5]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(6.3467,  6.3482, 6.347034915, 20);

    $this->assertEquals('6.3467–6.3482 [20;x̄=6.34703]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(0.00000001,  1, (1 - 0.00000001) / 2, 20);

    $this->assertEquals('1.0E-8–1 [20;x̄=0.5]', $this->html2text(statistical_values($stat_vals)));

    $stat_vals = $this->create_statistical_values(22,  23, 22.5, 4);

    $this->assertEquals('22–23 [4;x̄=22.5]', $this->html2text(statistical_values($stat_vals)));

    // see https://dev.e-taxonomy.eu/redmine/issues/8771#note-17

    $stat_vals = $this->create_statistical_values(22,  23, 22.047619, 24);

    $this->assertEquals('22–23 [24;x̄=22]', $this->html2text(statistical_values($stat_vals)));

  }

  function test_statistical_values_no_min_max() {

    $stat_vals = $this->create_statistical_values(null,  null, 0.1234, 5);

    $this->assertEquals('0.1234 [5]', $this->html2text(statistical_values($stat_vals)));

    // as discussed in https://dev.e-taxonomy.eu/redmine/issues/8771#note-16 variance etc should not be suppressed

    $stat_vals = $this->create_statistical_values(null,  null, 0.1234, 5, 0.3, 0.12);

    $this->assertEquals('0.1234 [5;σ²=0.3;σ=0.12]', $this->html2text(statistical_values($stat_vals)));

  }

  function test_statistical_values_with_unit() {

    $stat_vals = $this->create_statistical_values(2.2,  8.7, 5.234, 5, 0.3, 0.12);

    $this->assertEquals('2.2–8.7 cm [5;x̄=5;σ²=0.3;σ=0.12]', $this->html2text(statistical_values($stat_vals, 'cm')));

  }

  function test_statistical_values_no_brackets() {

    $stat_vals = $this->create_statistical_values(2.2,  8.7);

    $this->assertEquals('2.2–8.7 cm', $this->html2text(statistical_values($stat_vals, 'cm')));

    $stat_vals = $this->create_statistical_values(null,  null, 5.3);

    $this->assertEquals('5.3 m', $this->html2text(statistical_values($stat_vals, 'm')));

  }

}