Add tests for MessageBodyClientHttpResponseWrapper

Closes gh-26984

spring-web/src/test/java/org/springframework/web/client/MessageBodyClientHttpResponseWrapperTests.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2002-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.web.client;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.client.ClientHttpResponse;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * Unit tests for {MessageBodyClientHttpResponseWrapper}.
+ *
+ * @author Yin-Jui Liao
+ */
+class MessageBodyClientHttpResponseWrapperTests {
+
+	private final ClientHttpResponse response = mock(ClientHttpResponse.class);
+
+	@Test
+	void testMessageBodyNotExist() throws IOException {
+		given(response.getBody()).willReturn(null);
+		MessageBodyClientHttpResponseWrapper responseWrapper = new MessageBodyClientHttpResponseWrapper(response);
+		assertThat(responseWrapper.hasEmptyMessageBody()).isTrue();
+	}
+
+	@Test
+	void testMessageBodyExist() throws IOException {
+		String body = "Accepted request";
+		InputStream stream = new ByteArrayInputStream(body.getBytes());
+		given(response.getBody()).willReturn(stream);
+		MessageBodyClientHttpResponseWrapper responseWrapper = new MessageBodyClientHttpResponseWrapper(response);
+		assertThat(responseWrapper.hasEmptyMessageBody()).isFalse();
+	}
+}