fixing some psalm 5 complaints (#1110)

Whilst investigating upgrading to psalm 5, I notice that it generates a lot of new complaints. This fixes the ones that looked legit and
require an API change, or were trivial. Does not upgrade to psalm 5 yet, though. That's a bigger job for another day.

examples/traces/exporters/in_memory.php

@@ -34,6 +34,7 @@
 $childSpan2->end();
 $childSpan1->end();
 $rootSpan->end();
+$rootScope->detach();
 
 /** @var SpanDataInterface $span */
 foreach ($storage as $span) {

src/API/Signals.php

@@ -4,9 +4,7 @@
 
 namespace OpenTelemetry\API;
 
-use InvalidArgumentException;
-
-class Signals
+interface Signals
 {
     /** @var string  */
     public const TRACE = 'trace';
@@ -20,11 +18,4 @@ class Signals
         self::METRICS,
         self::LOGS,
     ];
-
-    public static function validate(string $signal): void
-    {
-        if (!in_array($signal, self::SIGNALS)) {
-            throw new InvalidArgumentException('Unknown signal: ' . $signal);
-        }
-    }
 }

src/API/Trace/SpanKind.php

@@ -7,26 +7,11 @@
 /**
  * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/trace/api.md#spankind
  */
-final class SpanKind
+interface SpanKind
 {
     public const KIND_INTERNAL = 0;
     public const KIND_CLIENT = 1;
     public const KIND_SERVER = 2;
     public const KIND_PRODUCER = 3;
     public const KIND_CONSUMER = 4;
-
-    public static function getChoices(): array
-    {
-        return [
-            self::KIND_INTERNAL,
-            self::KIND_CLIENT,
-            self::KIND_SERVER,
-            self::KIND_PRODUCER,
-            self::KIND_CONSUMER,
-        ];
-    }
-
-    private function __construct()
-    {
-    }
 }

src/API/Trace/StatusCode.php

@@ -7,22 +7,9 @@
 /**
  * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/trace/api.md#set-status
  */
-final class StatusCode
+interface StatusCode
 {
     public const STATUS_UNSET = 'Unset';
     public const STATUS_OK = 'Ok';
     public const STATUS_ERROR = 'Error';
-
-    public function getChoices(): array
-    {
-        return [
-            self::STATUS_UNSET,
-            self::STATUS_OK,
-            self::STATUS_ERROR,
-        ];
-    }
-
-    private function __construct()
-    {
-    }
 }

src/Contrib/Otlp/OtlpHttpTransportFactory.php

@@ -11,6 +11,7 @@
 class OtlpHttpTransportFactory implements TransportFactoryInterface
 {
     private const DEFAULT_COMPRESSION = 'none';
+
     public function create(
         string $endpoint,
         string $contentType,

src/SDK/Common/Adapter/HttpDiscovery/DependencyResolver.php

@@ -71,11 +71,6 @@ public function resolveUriFactory(): UriFactoryInterface
         return $this->messageFactoryResolver->resolveUriFactory();
     }
 
-    public function resolveHttpClient(): ClientInterface
-    {
-        return $this->psrClientResolver->resolvePsrClient();
-    }
-
     public function resolveHttpPlugAsyncClient(): HttpAsyncClient
     {
         return $this->httpPlugClientResolver->resolveHttpPlugAsyncClient();

src/SDK/Common/Export/Http/PsrTransportFactory.php

@@ -57,7 +57,7 @@ public function create(
             $endpoint,
             $contentType,
             $headers,
-            (array) $compression,
+            PsrUtils::compression($compression),
             $retryDelay,
             $maxRetries,
         );

src/SDK/Common/Export/Http/PsrUtils.php

@@ -104,6 +104,24 @@ public static function decode(string $value, array $encodings): string
         return $value;
     }
 
+    /**
+     * Resolve an array or CSV of compression types to a list
+     */
+    public static function compression($compression): array
+    {
+        if (is_array($compression)) {
+            return $compression;
+        }
+        if (!$compression) {
+            return [];
+        }
+        if (strpos($compression, ',') === false) {
+            return [$compression];
+        }
+
+        return array_map('trim', explode(',', $compression));
+    }
+
     private static function encoder(string $encoding): ?callable
     {
         static $encoders;

tests/Unit/Context/ScopeTest.php

@@ -116,7 +116,7 @@ public function test_scope_local_storage_is_preserved_between_attach_and_scope()
         $scope['key'] = 'value';
         $scope = $storage->scope();
         $this->assertNotNull($scope);
-        $this->assertArrayHasKey('key', $scope); /** @phpstan-ignore-line */
+        $this->assertArrayHasKey('key', $scope);
         $this->assertSame('value', $scope['key']);
 
         unset($scope['key']);

tests/Unit/SDK/Common/Export/Http/PsrUtilsTest.php

@@ -91,4 +91,23 @@ public function test_decode_stream_unknown_encoding(): void
 
         PsrUtils::decode('', ['invalid']);
     }
+
+    /**
+     * @dataProvider compressionProvider
+     */
+    public function test_resolve_compression($input, $expected): void
+    {
+        $this->assertSame($expected, PsrUtils::compression($input));
+    }
+
+    public static function compressionProvider(): array
+    {
+        return [
+            ['gzip', ['gzip']],
+            ['', []],
+            ['gzip,br', ['gzip','br']],
+            ['gzip , brotli', ['gzip','brotli']],
+            [['gzip'], ['gzip']],
+        ];
+    }
 }