test: add flush failure coverage for LoggingSpanExporter and LoggingMetricExporter

Author: ADITYA-CODE-SOURCE

exporters/logging/src/test/java/io/opentelemetry/exporter/logging/LoggingMetricExporterTest.java

@@ -25,6 +25,7 @@
 import java.util.Collections;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Handler;
 import java.util.logging.Logger;
 import java.util.logging.SimpleFormatter;
 import java.util.logging.StreamHandler;
@@ -101,6 +102,23 @@ public synchronized void flush() {
     assertThat(flushed.get()).isTrue();
   }
 
+  @Test
+  void flush_failure() {
+    Handler failingHandler =
+        new StreamHandler(new PrintStream(new ByteArrayOutputStream()), new SimpleFormatter()) {
+          @Override
+          public synchronized void flush() {
+            throw new RuntimeException("Flush failed");
+          }
+        };
+    Logger.getLogger(LoggingMetricExporter.class.getName()).addHandler(failingHandler);
+    try {
+      assertThat(exporter.flush().isSuccess()).isFalse();
+    } finally {
+      Logger.getLogger(LoggingMetricExporter.class.getName()).removeHandler(failingHandler);
+    }
+  }
+
   @Test
   void shutdown() {
     assertThat(exporter.shutdown().isSuccess()).isTrue();

exporters/logging/src/test/java/io/opentelemetry/exporter/logging/LoggingSpanExporterTest.java

@@ -31,6 +31,7 @@
 import java.util.Collections;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Handler;
 import java.util.logging.Logger;
 import java.util.logging.SimpleFormatter;
 import java.util.logging.StreamHandler;
@@ -139,6 +140,23 @@ public synchronized void flush() {
     assertThat(flushed.get()).isTrue();
   }
 
+  @Test
+  void flush_failure() {
+    Handler failingHandler =
+        new StreamHandler(new PrintStream(new ByteArrayOutputStream()), new SimpleFormatter()) {
+          @Override
+          public synchronized void flush() {
+            throw new RuntimeException("Flush failed");
+          }
+        };
+    Logger.getLogger(LoggingSpanExporter.class.getName()).addHandler(failingHandler);
+    try {
+      assertThat(exporter.flush().isSuccess()).isFalse();
+    } finally {
+      Logger.getLogger(LoggingSpanExporter.class.getName()).removeHandler(failingHandler);
+    }
+  }
+
   @Test
   void shutdown() {
     assertThat(exporter.shutdown().isSuccess()).isTrue();