Enable leak detection in Netty 5 tests

See gh-29310

spring-core/src/test/java/org/springframework/core/codec/Netty5BufferDecoderTests.java

@@ -87,7 +87,11 @@ class Netty5BufferDecoderTests extends AbstractDecoderTests<Netty5BufferDecoder>
 	}
 
 	private Consumer<Buffer> expectByteBuffer(Buffer expected) {
-		return actual -> assertThat(actual).isEqualTo(expected);
+		return actual -> {
+			try (actual; expected) {
+				assertThat(actual).isEqualTo(expected);
+			}
+		};
 	}
 
 }

spring-core/src/test/java/org/springframework/core/io/buffer/DataBufferTests.java

@@ -534,8 +534,12 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 		ByteBuffer result = buffer.asByteBuffer(1, 2);
 		assertThat(result.capacity()).isEqualTo(2);
 
-		assumeFalse(bufferFactory instanceof Netty5DataBufferFactory,
-				"Netty 5 does share the internal buffer");
+		boolean isNetty5DataBufferFactory = bufferFactory instanceof Netty5DataBufferFactory;
+		if (isNetty5DataBufferFactory) {
+			DataBufferUtils.release(buffer);
+		}
+
+		assumeFalse(isNetty5DataBufferFactory, "Netty 5 does share the internal buffer");
 
 		buffer.write((byte) 'c');
 		assertThat(result.remaining()).isEqualTo(2);
@@ -774,6 +778,9 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 
 		assertThat(result).isEqualTo(bytes);
 
+		if (bufferFactory instanceof Netty5DataBufferFactory) {
+			release(slice);
+		}
 		release(buffer);
 	}
 

spring-core/src/testFixtures/java/org/springframework/core/testfixture/codec/AbstractDecoderTests.java

@@ -20,6 +20,7 @@ import java.time.Duration;
 import java.util.Map;
 import java.util.function.Consumer;
 
+import io.netty5.buffer.Buffer;
 import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -209,7 +210,13 @@ public abstract class AbstractDecoderTests<D extends Decoder<?>> extends Abstrac
 
 		Flux<DataBuffer> buffer = Mono.from(input).concatWith(Flux.error(new InputException()));
 		assertThatExceptionOfType(InputException.class).isThrownBy(() ->
-				this.decoder.decode(buffer, outputType, mimeType, hints).blockLast(Duration.ofSeconds(5)));
+				this.decoder.decode(buffer, outputType, mimeType, hints)
+						.doOnNext(o -> {
+							if (o instanceof Buffer buf) {
+								buf.close();
+							}
+						})
+						.blockLast(Duration.ofSeconds(5)));
 	}
 
 	/**
@@ -226,7 +233,12 @@ public abstract class AbstractDecoderTests<D extends Decoder<?>> extends Abstrac
 	protected void testDecodeCancel(Publisher<DataBuffer> input, ResolvableType outputType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
 
-		Flux<?> result = this.decoder.decode(input, outputType, mimeType, hints);
+		Flux<?> result = this.decoder.decode(input, outputType, mimeType, hints)
+				.doOnNext(o -> {
+					if (o instanceof Buffer buf) {
+						buf.close();
+					}
+				});
 		StepVerifier.create(result).expectNextCount(1).thenCancel().verify();
 	}