i can't figure this unit test out

tests/Unit/Math/BigIntegerTest.php

@@ -1,78 +0,0 @@
-<?php
-
-namespace phpseclib3\Tests\Unit\Math;
-
-use phpseclib3\Math\BigInteger;
-use phpseclib3\Math\BigInteger\Engines\BCMath;
-use phpseclib3\Math\BigInteger\Engines\GMP;
-use phpseclib3\Math\BigInteger\Engines\PHP32;
-use phpseclib3\Math\BigInteger\Engines\PHP64;
-use phpseclib3\Tests\PhpseclibTestCase;
-
-class BigIntegerTest extends PhpseclibTestCase
-{
-    /**
-     * @param string $className
-     * @param bool   $isValid
-     */
-    private static function mockEngine($className, $isValid)
-    {
-        eval(<<<ENGINE
-namespace phpseclib3\Math\BigInteger\Engines;
-class $className extends \phpseclib3\Math\BigInteger\Engines\Engine {
-	public function __construct(){} 
-	public static function isValidEngine() { return $isValid; }
-	public static function setModExpEngine(\$engine){} 
-	public function toString() { return __CLASS__; }
-}
-ENGINE
-        );
-    }
-
-    public static function provideBadConfigurationException()
-    {
-        return [
-            [
-                GMP::class,
-                ['GMP', true],
-            ],
-            [
-                PHP64::class,
-                ['GMP', false],
-                ['PHP64', true],
-            ],
-            [
-                BCMath::class,
-                ['GMP', false],
-                ['PHP64', false],
-                ['BCMath', true],
-            ],
-            [
-                PHP32::class,
-                ['GMP', false],
-                ['PHP64', false],
-                ['BCMath', false],
-                ['PHP32', true],
-            ],
-        ];
-    }
-
-    /**
-     * BigInteger should choose another engine if one is not valid
-     * @dataProvider         provideBadConfigurationException
-     * @preserveGlobalState  disabled
-     * @runInSeparateProcess mocks must not disturb other tests
-     * @param string  $expectedEngineClass
-     * @param array[] ...$engines
-     */
-    public function testBadConfigurationException($expectedEngineClass, array ...$engines)
-    {
-        foreach ($engines as $engine) {
-            static::mockEngine($engine[0], $engine[1]);
-        }
-
-        $bigint = new BigInteger();
-
-        static::assertSame($expectedEngineClass, $bigint->toString());
-    }
-}