Log only above warning by default

Author: mnapoli

README.md

@@ -27,6 +27,8 @@ The logger does not require any configuration:
 $logger = new \Bref\Logger\StderrLogger();
 ```
 
+By default messages **above the `warning` level** will be logged, the rest will be discarded.
+
 It is possible to log using any [PSR-3 log level](https://www.php-fig.org/psr/psr-3/#5-psrlogloglevel), the most common ones being:
 
 ```php
@@ -37,12 +39,12 @@ $logger->error('This is an error');
 ```
 
 ```
-[DEBUG] This is a debug message
-[INFO] This is an info
 [WARNING] This is a warning
 [ERROR] This is an error
 ```
 
+Messages under `warning` are not logged.
+
 ### Message placeholders
 
 [PSR-3 placeholders](https://www.php-fig.org/psr/psr-3/#12-message) can be used to insert information from the `$context` array into the message without having to concatenate strings manually:
@@ -79,3 +81,13 @@ Stack trace:
 #0 /var/task/index.php(86): main()
 ...
 ```
+
+### Log level
+
+It is possible to change the level above which messages are logged.
+
+For example to log all messages:
+
+```php
+$logger = new \Bref\Logger\StderrLogger(\Psr\Log\LogLevel::DEBUG);
+```

src/StderrLogger.php

@@ -3,23 +3,41 @@
 namespace Bref\Logger;
 
 use Psr\Log\AbstractLogger;
+use Psr\Log\LogLevel;
 
 /**
  * PSR-3 logger that logs into stderr.
  */
 class StderrLogger extends AbstractLogger
 {
+    private const LOG_LEVEL_MAP = [
+        LogLevel::EMERGENCY => 8,
+        LogLevel::ALERT => 7,
+        LogLevel::CRITICAL => 6,
+        LogLevel::ERROR => 5,
+        LogLevel::WARNING => 4,
+        LogLevel::NOTICE => 3,
+        LogLevel::INFO => 2,
+        LogLevel::DEBUG => 1,
+    ];
+
+    /** @var string */
+    private $logLevel;
+
     /** @var string|null */
     private $url;
 
     /** @var resource|null */
     private $stream;
 
     /**
+     * @param string $logLevel The log level above which messages will be logged. Messages under this log level will be ignored.
      * @param resource|string $stream If unsure leave the default value.
      */
-    public function __construct($stream = 'php://stderr')
+    public function __construct(string $logLevel = LogLevel::WARNING, $stream = 'php://stderr')
     {
+        $this->logLevel = $logLevel;
+
         if (is_resource($stream)) {
             $this->stream = $stream;
         } elseif (is_string($stream)) {
@@ -34,6 +52,10 @@ public function __construct($stream = 'php://stderr')
      */
     public function log($level, $message, array $context = []): void
     {
+        if (self::LOG_LEVEL_MAP[$level] < self::LOG_LEVEL_MAP[$this->logLevel]) {
+            return;
+        }
+
         $this->openStderr();
 
         $message = $this->interpolate($message, $context);

tests/StderrLoggerTest.php

@@ -4,6 +4,7 @@
 
 use Bref\Logger\StderrLogger;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LogLevel;
 
 class StderrLoggerTest extends TestCase
 {
@@ -17,7 +18,7 @@ public function setUp(): void
         parent::setUp();
 
         $this->stream = fopen('php://memory', 'a+');
-        $this->logger = new StderrLogger($this->stream);
+        $this->logger = new StderrLogger(LogLevel::DEBUG, $this->stream);
     }
 
     public function test log messages to stderr()
@@ -45,6 +46,29 @@ public function test log messages to stderr()
 );
     }
 
+    public function test logs above the configured log level()
+    {
+        $this->logger = new StderrLogger(LogLevel::WARNING, $this->stream);
+        $this->logger->debug('Debug');
+        $this->logger->info('Info');
+        $this->logger->notice('Notice');
+        $this->logger->warning('Alert');
+        $this->logger->error('Error');
+        $this->logger->critical('Critical');
+        $this->logger->alert('Alert');
+        $this->logger->emergency('Emergency');
+
+        $this->assertLogs(<<<'LOGS'
+[WARNING] Alert
+[ERROR] Error
+[CRITICAL] Critical
+[ALERT] Alert
+[EMERGENCY] Emergency
+
+LOGS
+        );
+    }
+
     /**
      * @param mixed $contextValue
      *
@@ -89,11 +113,12 @@ public function test exceptions are logged()
         ]);
 
         $currentFile = __FILE__;
-        $this->assertLogsStartWith(<<<LOGS
+        $this->assertLogsMatch(<<<LOGS
 [INFO] Exception
-InvalidArgumentException: This is an exception message in $currentFile:115
+InvalidArgumentException: This is an exception message in $currentFile:%d
 Stack trace:
-#0 $currentFile(88): Bref\Logger\Test\StderrLoggerTest->createTestException()
+#0 $currentFile(%d): Bref\Logger\Test\StderrLoggerTest->createTestException()
+#1 %a
 LOGS
         );
     }
@@ -104,10 +129,10 @@ private function assertLogs(string $expectedLog): void
         self::assertSame($expectedLog, fread($this->stream, fstat($this->stream)['size']));
     }
 
-    private function assertLogsStartWith(string $expectedLog): void
+    private function assertLogsMatch(string $expectedLog): void
     {
         rewind($this->stream);
-        self::assertStringStartsWith($expectedLog, fread($this->stream, fstat($this->stream)['size']));
+        self::assertStringMatchesFormat($expectedLog, fread($this->stream, fstat($this->stream)['size']));
     }
 
     private function createTestException(): \InvalidArgumentException