Restore image-thumbnail-samples

function-based-stream-app-samples/image-thumbnail-samples/image-thumbnail-processor/src/test/java/io/spring/example/image/thumbnail/processor/ThumbnailProcessorTests.java

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+/*
+ * Copyright 2020-2020 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 io.spring.example.image.thumbnail.processor;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ThumbnailProcessorTests {
+	@TempDir
+	File tempDir;
+
+	@Test
+	void test() throws IOException {
+		Resource resource = new ClassPathResource("firetruck.jpg");
+		byte[] data = readAllBytes(resource);
+		byte[] thumbnail = new ThumbnailProcessor().apply(data);
+		Path path = Paths.get(tempDir.getAbsolutePath(), "thumbnail.jpg");
+		Files.write(path, thumbnail);
+		assertThat(Files.exists(path)).isTrue();
+	}
+
+	private byte[] readAllBytes(Resource resource) throws IOException {
+		InputStream is = resource.getInputStream();
+		byte[] bytes = new byte[is.available()];
+		is.read(bytes);
+		return bytes;
+	}
+}