Consolidate CPUInfo finder (#16)

Split the "get the string which contains the info" and the "retrieve the info from the string" in order to add unit tests to the 2nd one.

src/CpuInfoFinder.php

@@ -16,7 +16,6 @@
 use function count;
 use function file_get_contents;
 use function is_file;
-use function preg_match_all;
 
 /**
  * Find the number of CPU cores looking up at the cpuinfo file which is available
@@ -25,8 +24,10 @@
  * @see https://github.com/paratestphp/paratest/blob/c163539818fd96308ca8dc60f46088461e366ed4/src/Runners/PHPUnit/Options.php#L903-L909
  * @see https://unix.stackexchange.com/questions/146051/number-of-processors-in-proc-cpuinfo
  */
-final class CpuInfoFinder implements CpuCoreFinder
+final class CpuInfoFinder
 {
+    private const CPU_INFO_PATH = '/proc/cpuinfo';
+
     private function __construct()
     {
     }
@@ -36,18 +37,35 @@ private function __construct()
      */
     public static function find(): ?int
     {
-        // from brianium/paratest
-        if (is_file('/proc/cpuinfo')) {
-            // Linux (and potentially Windows with linux sub systems)
-            $cpuinfo = file_get_contents('/proc/cpuinfo');
+        $cpuInfo = self::getCpuInfo();
 
-            if (false !== $cpuinfo) {
-                preg_match_all('/^processor/m', $cpuinfo, $matches);
+        return null === $cpuInfo ? null : self::countCpuCores($cpuInfo);
+    }
 
-                return count($matches[0]);
-            }
+    private static function getCpuInfo(): ?string
+    {
+        if (!is_file(self::CPU_INFO_PATH)) {
+            return null;
         }
 
-        return null;
+        $cpuInfo = file_get_contents(self::CPU_INFO_PATH);
+
+        return false === $cpuInfo
+            ? null
+            : $cpuInfo;
+    }
+
+    /**
+     * @internal
+     *
+     * @return positive-int|null
+     */
+    public static function countCpuCores(string $cpuInfo): ?int
+    {
+        preg_match_all('/^processor/m', $cpuInfo, $matches);
+
+        $processorCount = count($matches[0]);
+
+        return $processorCount > 0 ? $processorCount : null;
     }
 }

tests/CpuInfoFinderTest.php

@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * This file is part of the Fidry CPUCounter Config package.
+ *
+ * (c) Théo FIDRY <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Fidry\CpuCounter\Test;
+
+use Fidry\CpuCounter\CpuInfoFinder;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \Fidry\CpuCounter\CpuInfoFinder
+ *
+ * @internal
+ */
+final class CpuInfoFinderTest extends TestCase
+{
+    /**
+     * @dataProvider cpuInfoProvider
+     */
+    public function test_it_can_count_the_number_of_cpu_cores(
+        string $cpuInfo,
+        ?int $expected
+    ): void {
+        $actual = CpuInfoFinder::countCpuCores($cpuInfo);
+
+        self::assertSame($expected, $actual);
+    }
+
+    public static function cpuInfoProvider(): iterable
+    {
+        yield 'empty' => [
+            <<<'EOF'
+
+                EOF,
+            null,
+        ];
+
+        // $ docker run  --tty --rm --platform linux/amd64 alpine:3.14 cat /proc/cpuinfo
+        yield 'example from an alpine Docker image' => [
+            <<<'EOF'
+                processor	: 0
+                BogoMIPS	: 48.00
+                Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint
+                CPU implementer	: 0x00
+                CPU architecture: 8
+                CPU variant	: 0x0
+                CPU part	: 0x000
+                CPU revision	: 0
+
+                processor	: 1
+                BogoMIPS	: 48.00
+                Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint
+                CPU implementer	: 0x00
+                CPU architecture: 8
+                CPU variant	: 0x0
+                CPU part	: 0x000
+                CPU revision	: 0
+
+                processor	: 2
+                BogoMIPS	: 48.00
+                Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint
+                CPU implementer	: 0x00
+                CPU architecture: 8
+                CPU variant	: 0x0
+                CPU part	: 0x000
+                CPU revision	: 0
+
+                EOF,
+            3,
+        ];
+    }
+}