Add unit tests for HiveShim appendReadColumns

sql/hive/src/test/scala/org/apache/spark/sql/hive/HiveShimSuite.scala

@@ -0,0 +1,44 @@
+/*
+ * 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.spark.sql.hive
+
+import scala.collection.JavaConverters._
+import scala.language.implicitConversions
+
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.hive.serde2.ColumnProjectionUtils
+
+import org.apache.spark.SparkFunSuite
+
+class HiveShimSuite extends SparkFunSuite {
+
+  test("appendReadColumns") {
+    val conf = new Configuration
+    val ids = Seq(1, 2, 3).map(Int.box)
+    val names = Seq("a", "b", "c")
+    val moreIds = Seq(4, 5).map(Int.box)
+    val moreNames = Seq("d", "e")
+
+    // test when READ_COLUMN_NAMES_CONF_STR is empty
+    HiveShim.appendReadColumns(conf, ids, names)
+    assert(names.asJava === ColumnProjectionUtils.getReadColumnNames(conf))
+
+    // test when READ_COLUMN_NAMES_CONF_STR is non-empty
+    HiveShim.appendReadColumns(conf, moreIds, moreNames)
+    assert((names ++ moreNames).asJava === ColumnProjectionUtils.getReadColumnNames(conf))
+  }
+}