feat(tia): adds poc

src/Plugins/Tia/Recorder.php

@@ -0,0 +1,237 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use ReflectionClass;
+use ReflectionException;
+
+/**
+ * Captures per-test file coverage using the PCOV driver.
+ *
+ * Acts as a singleton because PCOV has a single global collection state and
+ * the recorder is wired into PHPUnit through two distinct subscribers
+ * (`Prepared` / `Finished`) that must share context.
+ *
+ * @internal
+ */
+final class Recorder
+{
+    private static ?self $instance = null;
+
+    /**
+     * Test file currently being recorded, or `null` when idle.
+     */
+    private ?string $currentTestFile = null;
+
+    /**
+     * Aggregated map: absolute test file → set<absolute source file>.
+     *
+     * @var array<string, array<string, true>>
+     */
+    private array $perTestFiles = [];
+
+    /**
+     * Cached class → test file resolution.
+     *
+     * @var array<string, string|null>
+     */
+    private array $classFileCache = [];
+
+    private bool $active = false;
+
+    private bool $driverChecked = false;
+
+    private bool $driverAvailable = false;
+
+    private string $driver = 'none';
+
+    public static function instance(): self
+    {
+        return self::$instance ??= new self;
+    }
+
+    public function activate(): void
+    {
+        $this->active = true;
+    }
+
+    public function isActive(): bool
+    {
+        return $this->active;
+    }
+
+    public function driverAvailable(): bool
+    {
+        if (! $this->driverChecked) {
+            if (function_exists('pcov\\start')) {
+                $this->driver = 'pcov';
+                $this->driverAvailable = true;
+            } elseif (function_exists('xdebug_start_code_coverage')) {
+                // Probe: Xdebug silently emits a warning and refuses to start
+                // when not in coverage mode. Suppress + check for mode errors.
+                $ok = @\xdebug_start_code_coverage();
+
+                if ($ok === null || $ok) {
+                    @\xdebug_stop_code_coverage(false);
+                    $this->driver = 'xdebug';
+                    $this->driverAvailable = true;
+                }
+            }
+
+            $this->driverChecked = true;
+        }
+
+        return $this->driverAvailable;
+    }
+
+    public function driver(): string
+    {
+        $this->driverAvailable();
+
+        return $this->driver;
+    }
+
+    public function beginTest(string $className, string $methodName, string $fallbackFile): void
+    {
+        if (! $this->active || ! $this->driverAvailable()) {
+            return;
+        }
+
+        $file = $this->resolveTestFile($className, $fallbackFile);
+
+        if ($file === null) {
+            return;
+        }
+
+        $this->currentTestFile = $file;
+
+        if ($this->driver === 'pcov') {
+            \pcov\clear();
+            \pcov\start();
+
+            return;
+        }
+
+        // Xdebug
+        \xdebug_start_code_coverage();
+    }
+
+    public function endTest(): void
+    {
+        if (! $this->active || ! $this->driverAvailable() || $this->currentTestFile === null) {
+            return;
+        }
+
+        if ($this->driver === 'pcov') {
+            \pcov\stop();
+            /** @var array<string, mixed> $data */
+            $data = \pcov\collect(\pcov\inclusive);
+        } else {
+            /** @var array<string, mixed> $data */
+            $data = \xdebug_get_code_coverage();
+            // `true` resets Xdebug's internal buffer so the next `start()`
+            // does not accumulate earlier tests' coverage into the current
+            // one — otherwise the graph becomes progressively polluted.
+            \xdebug_stop_code_coverage(true);
+        }
+
+        foreach (array_keys($data) as $sourceFile) {
+            $this->perTestFiles[$this->currentTestFile][$sourceFile] = true;
+        }
+
+        $this->currentTestFile = null;
+    }
+
+    /**
+     * @return array<string, array<int, string>> absolute test file → list of absolute source files.
+     */
+    public function perTestFiles(): array
+    {
+        $out = [];
+
+        foreach ($this->perTestFiles as $testFile => $sources) {
+            $out[$testFile] = array_keys($sources);
+        }
+
+        return $out;
+    }
+
+    private function resolveTestFile(string $className, string $fallbackFile): ?string
+    {
+        if (array_key_exists($className, $this->classFileCache)) {
+            $file = $this->classFileCache[$className];
+        } else {
+            $file = $this->readPestFilename($className);
+            $this->classFileCache[$className] = $file;
+        }
+
+        if ($file !== null) {
+            return $file;
+        }
+
+        if ($fallbackFile !== '' && $fallbackFile !== 'unknown' && ! str_contains($fallbackFile, "eval()'d")) {
+            return $fallbackFile;
+        }
+
+        return null;
+    }
+
+    /**
+     * Resolves the file that *defines* the test class.
+     *
+     * Order of preference:
+     *   1. Pest's generated `$__filename` static — the original `*.php` file
+     *      containing the `test()` calls (the eval'd class itself has no file).
+     *   2. `ReflectionClass::getFileName()` — the concrete class's file. This
+     *      is intentionally more specific than `ReflectionMethod::getFileName()`
+     *      (which would return the *trait* file for methods brought in via
+     *      `uses SharedTestBehavior`).
+     */
+    private function readPestFilename(string $className): ?string
+    {
+        if (! class_exists($className, false)) {
+            return null;
+        }
+
+        try {
+            $reflection = new ReflectionClass($className);
+        } catch (ReflectionException) {
+            return null;
+        }
+
+        if ($reflection->hasProperty('__filename')) {
+            try {
+                $property = $reflection->getProperty('__filename');
+
+                if ($property->isStatic()) {
+                    $value = $property->getValue();
+
+                    if (is_string($value) && $value !== '') {
+                        return $value;
+                    }
+                }
+            } catch (ReflectionException) {
+                // fall through to getFileName()
+            }
+        }
+
+        $file = $reflection->getFileName();
+
+        return $file !== false && $file !== '' ? $file : null;
+    }
+
+    /**
+     * Clears all captured state. Useful for long-running hosts (daemons,
+     * PHP-FPM, watchers) that invoke Pest multiple times in a single process
+     * — without this, coverage from run N would bleed into run N+1.
+     */
+    public function reset(): void
+    {
+        $this->currentTestFile = null;
+        $this->perTestFiles = [];
+        $this->classFileCache = [];
+        $this->active = false;
+    }
+}