Unit test for Java Parquet source operator

wayang-platforms/wayang-java/pom.xml

@@ -50,16 +50,13 @@
             <version>1.1.2-SNAPSHOT</version>
         </dependency>
         <dependency>
-            <groupId>org.apache.hadoop</groupId>
-            <artifactId>hadoop-common</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.hadoop</groupId>
-            <artifactId>hadoop-hdfs</artifactId>
+            <groupId>org.apache.parquet</groupId>
+            <artifactId>parquet-avro</artifactId>
+            <version>1.15.2</version>
         </dependency>
         <dependency>
             <groupId>org.apache.parquet</groupId>
-            <artifactId>parquet-avro</artifactId>
+            <artifactId>parquet-hadoop</artifactId>
             <version>1.15.2</version>
         </dependency>
         <dependency>
@@ -72,11 +69,6 @@
             <artifactId>slf4j-api</artifactId>
             <version>2.0.6</version>
         </dependency>
-        <dependency>
-            <groupId>org.apache.logging.log4j</groupId>
-            <artifactId>log4j-slf4j-impl</artifactId>
-            <version>2.20.0</version>
-        </dependency>
         <!-- Mockito for mocking -->
         <dependency>
             <groupId>org.mockito</groupId>
@@ -86,4 +78,4 @@
         </dependency>
     </dependencies>
 
-</project>
+</project>

wayang-platforms/wayang-java/src/test/java/org/apache/wayang/java/operators/JavaParquetSourceTest.java

@@ -0,0 +1,115 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ *
+ *     http://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.apache.wayang.java.operators;
+
+import org.apache.wayang.basic.data.Record;
+import org.apache.wayang.core.platform.ChannelInstance;
+import org.apache.wayang.java.channels.StreamChannel;
+import org.junit.jupiter.api.Test;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Test suite for {@link JavaParquetSource}.
+ */
+class JavaParquetSourceTest extends JavaExecutionOperatorTestBase {
+
+    @Test
+    void testReadAllColumns() {
+            Path parquetFile = Paths.get("src/test/resources/data.parquet").toAbsolutePath();
+            JavaParquetSource source = new JavaParquetSource(parquetFile.toUri().toString(), null);
+
+            ChannelInstance[] inputs = new ChannelInstance[0];
+            ChannelInstance[] outputs = new ChannelInstance[]{createStreamChannelInstance()};
+            evaluate(source, inputs, outputs);
+
+            List<Record> result = ((StreamChannel.Instance) outputs[0]).<Record>provideStream().toList();
+
+            assertEquals(3, result.size());
+            assertEquals("alice", result.get(0).getString(0));
+            assertEquals(30, result.get(0).getInt(1));
+            assertEquals("bob", result.get(1).getString(0));
+            assertEquals(25, result.get(1).getInt(1));
+            assertEquals("carol", result.get(2).getString(0));
+            assertEquals(41, result.get(2).getInt(1));
+    }
+
+    @Test
+    void testReadWithProjection() {
+            Path parquetFile = Paths.get("src/test/resources/data.parquet").toAbsolutePath();
+            JavaParquetSource source = new JavaParquetSource(parquetFile.toUri().toString(), new String[]{"name"});
+
+            ChannelInstance[] inputs = new ChannelInstance[0];
+            ChannelInstance[] outputs = new ChannelInstance[]{createStreamChannelInstance()};
+            evaluate(source, inputs, outputs);
+
+            List<Record> result = ((StreamChannel.Instance) outputs[0]).<Record>provideStream().toList();
+
+            assertEquals(3, result.size());
+            // Each projected record contains only the "name" column
+            assertEquals(1, result.get(0).size());
+            assertEquals("alice", result.get(0).getString(0));
+            assertEquals("bob", result.get(1).getString(0));
+            assertEquals("carol", result.get(2).getString(0));
+    }
+
+    /* The following lines were used to create the sample Parquet file.
+    We keep it here for reference, but we don't want to run it in the test suite as it adds a dependency on Hadoop and Parquet libraries and complicates the test setup.
+    */
+
+    /*
+    private static final Schema SCHEMA = SchemaBuilder.record("TestRecord")
+            .namespace("org.apache.wayang.test")
+            .fields()
+            .requiredString("name")
+            .requiredInt("age")
+            .endRecord();
+
+    private static Path writeSampleParquet(Path dir) throws IOException {
+        Path file = dir.resolve("data.parquet");
+        org.apache.hadoop.fs.Path hadoopPath = new org.apache.hadoop.fs.Path(file.toUri());
+        List<GenericRecord> records = Arrays.asList(
+                makeRecord("alice", 30),
+                makeRecord("bob", 25),
+                makeRecord("carol", 41)
+        );
+        try (ParquetWriter<GenericRecord> writer = AvroParquetWriter.<GenericRecord>builder(hadoopPath)
+                .withSchema(SCHEMA)
+                .withConf(new Configuration())
+                .withCompressionCodec(CompressionCodecName.UNCOMPRESSED)
+                .build()) {
+            for (GenericRecord record : records) {
+                writer.write(record);
+            }
+        }
+        return file;
+    }
+
+    private static GenericRecord makeRecord(String name, int age) {
+        GenericRecord record = new GenericData.Record(SCHEMA);
+        record.put("name", name);
+        record.put("age", age);
+        return record;
+    }
+    */
+}