feat(log): Improve error log in OpenFeatureClient (#156)

Change log message to follow best practice of PSR3, Log Exception object
to help debuging, when provider throw Exception

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## This PR
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- Improve the log message and context, when the OpenFeatureClient catch
Exception

### Related Issues
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### Notes
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### Follow-up Tasks
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### How to test
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- Unit test updated to test the changes

---------

Signed-off-by: jaugustin <[email protected]>

Author: jaugustin

src/OpenFeatureClient.php

@@ -38,7 +38,6 @@
 
 use function array_merge;
 use function array_reverse;
-use function sprintf;
 
 class OpenFeatureClient implements Client, LoggerAwareInterface
 {
@@ -365,11 +364,12 @@ private function evaluateFlag(
             $hookExecutor->afterHooks($flagValueType, $hookContext, $resolutionDetails, $mergedRemainingHooks, $hookHints);
         } catch (Throwable $err) {
             $this->getLogger()->error(
-                sprintf(
-                    "An error occurred during feature flag evaluation of flag '%s': %s",
-                    $flagKey,
-                    $err->getMessage(),
-                ),
+                "An error occurred during feature flag evaluation of flag '{flagKey}': {errorMessage}",
+                [
+                    'flagKey' => $flagKey,
+                    'errorMessage' => $err->getMessage(),
+                    'exception' => $err,
+                ],
             );
 
             $error = $err instanceof ThrowableWithResolutionError ? $err->getResolutionError() : new ResolutionError(ErrorCode::GENERAL(), $err->getMessage());

tests/unit/OpenFeatureClientTest.php

@@ -27,6 +27,7 @@
 use OpenFeature\interfaces\provider\Provider;
 use Psr\Log\LoggerInterface;
 use ReflectionClass;
+use Throwable;
 
 class OpenFeatureClientTest extends TestCase
 {
@@ -556,7 +557,21 @@ public function testClientShouldLogInformativeErrorDuringAbnormalExecution(): vo
 
         /** @var LoggerInterface|MockInterface $mockLogger */
         $mockLogger = $this->mockery(LoggerInterface::class);
-        $mockLogger->shouldReceive('error')->once();
+        $mockLogger->shouldReceive('error')->with(
+            "An error occurred during feature flag evaluation of flag '{flagKey}': {errorMessage}",
+            Mockery::on(function ($context) {
+                $this->assertIsArray($context);
+                $this->assertArrayHasKey('flagKey', $context);
+                $this->assertSame('flagKey', $context['flagKey']);
+                $this->assertArrayHasKey('errorMessage', $context);
+                $this->assertSame('NETWORK_ERROR', $context['errorMessage']);
+                $this->assertArrayHasKey('exception', $context);
+                $this->assertInstanceOf(Throwable::class, $context['exception']);
+                $this->assertSame('NETWORK_ERROR', $context['exception']->getMessage());
+
+                return true;
+            }),
+        )->once();
         $api->setLogger($mockLogger);
 
         $mockProvider = $this->getDefaultMockProvider();