Implementation of the CHITEST() statistical function (#1960)

* Implementation of the CHITEST() statistical function

* A couple of additional edge case tests (rows = 1, columns = 1)

tests/PhpSpreadsheetTests/Calculation/Functions/Statistical/ChiTestTest.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Calculation\Functions\Statistical;
+
+use PhpOffice\PhpSpreadsheet\Calculation\Statistical;
+use PHPUnit\Framework\TestCase;
+
+class ChiTestTest extends TestCase
+{
+    /**
+     * @dataProvider providerCHITEST
+     *
+     * @param mixed $expectedResult
+     * @param mixed $actual
+     * @param mixed $expected
+     */
+    public function testCHITEST($expectedResult, $actual, $expected): void
+    {
+        $result = Statistical\Distributions\ChiSquared::test($actual, $expected);
+        self::assertEqualsWithDelta($expectedResult, $result, 1E-12);
+    }
+
+    public function providerCHITEST()
+    {
+        return require 'tests/data/Calculation/Statistical/CHITEST.php';
+    }
+}

tests/data/Calculation/Statistical/CHITEST.php

@@ -0,0 +1,39 @@
+<?php
+
+return [
+    [
+        0.0152703571482,
+        [[112, 76], [85, 95]],
+        [[100, 85], [70, 90]],
+    ],
+    [
+        0.000308192027,
+        [[58, 35], [11, 25], [10, 23]],
+        [[45.35, 47.65], [17.56, 18.44], [16.09, 16.91]],
+    ],
+    [
+        0.015888560447,
+        [[58], [11], [10]],
+        [[45.35], [17.56], [16.09]],
+    ],
+    [
+        0.008682970191,
+        [[58, 35]],
+        [[45.35, 47.65]],
+    ],
+    [
+        '#NUM!',
+        [[58, 11], [10, 35], [25]],
+        [[45.35, 17.56], [16.09, 47.65], [18.44, 16.91]],
+    ],
+    [
+        '#DIV/0!',
+        [[112, 76], [85, 95]],
+        [[100, 0], [70, 90]],
+    ],
+    [
+        '#NUM!',
+        [[112, 76], [85, 95]],
+        [[100, 85], [-70, 90]],
+    ],
+];