more unit tests

src/main/java/com/yahoo/sketches/pig/sampling/GetVarOptSamples.java

@@ -31,8 +31,6 @@
  * @author Jon Malkin
  */
 public class GetVarOptSamples extends EvalFunc<DataBag> {
-  // defined for test consistency
-
   private static final ArrayOfTuplesSerDe SERDE = new ArrayOfTuplesSerDe();
 
   @Override
@@ -51,16 +49,20 @@ public DataBag exec(final Tuple inputTuple) throws IOException {
   @Override
   public Schema outputSchema(final Schema input) {
     try {
+      if (input == null || input.size() == 0
+              || input.getField(0).type != DataType.BYTEARRAY) {
+        throw new IllegalArgumentException("Input to GetVarOptSamples must be a DataByteArray: "
+                + (input == null ? "null" : input.toString()));
+      }
+
       final Schema weightedSampleSchema = new Schema();
       weightedSampleSchema.add(new Schema.FieldSchema(WEIGHT_ALIAS, DataType.DOUBLE));
       weightedSampleSchema.add(new Schema.FieldSchema(RECORD_ALIAS, DataType.TUPLE));
 
       return new Schema(new Schema.FieldSchema(getSchemaName(this
               .getClass().getName().toLowerCase(), input), weightedSampleSchema, DataType.BAG));
     } catch (final FrontendException e) {
-      // fall through
+      return null;
     }
-
-    return null;
   }
 }

src/test/java/com/yahoo/sketches/pig/sampling/GetVarOptSamplesTest.java

@@ -0,0 +1,123 @@
+package com.yahoo.sketches.pig.sampling;
+
+import static com.yahoo.sketches.pig.sampling.VarOptCommonImpl.RECORD_ALIAS;
+import static com.yahoo.sketches.pig.sampling.VarOptCommonImpl.WEIGHT_ALIAS;
+import static com.yahoo.sketches.pig.sampling.VarOptSamplingTest.EPS;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertNull;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.fail;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.pig.data.DataBag;
+import org.apache.pig.data.DataByteArray;
+import org.apache.pig.data.DataType;
+import org.apache.pig.data.Tuple;
+import org.apache.pig.data.TupleFactory;
+import org.apache.pig.impl.logicalLayer.schema.Schema;
+import org.testng.annotations.Test;
+
+import com.yahoo.sketches.sampling.VarOptItemsSketch;
+
+public class GetVarOptSamplesTest {
+  private static final ArrayOfTuplesSerDe serDe_ = new ArrayOfTuplesSerDe();
+
+  @Test
+  public void checkDegenerateInput() {
+    final GetVarOptSamples udf = new GetVarOptSamples();
+
+    try {
+      assertNull(udf.exec(null));
+      assertNull(udf.exec(TupleFactory.getInstance().newTuple(0)));
+      assertNull(udf.exec(TupleFactory.getInstance().newTuple((Object) null)));
+    } catch (final IOException e) {
+      fail("Unexpected IOException");
+    }
+  }
+
+  @Test
+  public void checkExec() {
+    final int k = 10;
+    final int n = 25;  // exact mode
+    final GetVarOptSamples udf = new GetVarOptSamples();
+
+    try {
+      final VarOptItemsSketch<Tuple> vis = VarOptItemsSketch.newInstance(k);
+      double cumWt = 0.0;
+      for (int i = 1; i <= n; ++i) {
+        final Tuple t = TupleFactory.getInstance().newTuple(2);
+       final double wt = 1.0 * i;
+        t.set(0, wt);
+        t.set(1, i);
+        vis.update(t, wt);
+        cumWt += wt;
+      }
+
+      final DataByteArray dba = new DataByteArray(vis.toByteArray(serDe_));
+      final Tuple inputTuple = TupleFactory.getInstance().newTuple(dba);
+      final DataBag result = udf.exec(inputTuple);
+
+      double cumResultWt = 0.0;
+      for (Tuple sample : result) {
+        cumResultWt += (double) sample.get(0);
+        final Tuple record = (Tuple) sample.get(1);
+        final int id = (int) record.get(1);
+        assertTrue(id >= 1 && id <= n);
+      }
+      assertEquals(cumResultWt, cumWt, EPS);
+    } catch (final IOException e) {
+      fail("Unexpected IOException");
+    }
+  }
+
+  @Test
+  public void validOutputSchemaTest() throws IOException {
+    final GetVarOptSamples udf = new GetVarOptSamples();
+
+    final Schema serializedSketch = new Schema();
+    serializedSketch.add(new Schema.FieldSchema("field1", DataType.BYTEARRAY));
+    //final Schema inputSchema = new Schema();
+    //inputSchema.add(new Schema.FieldSchema("record", serializedSketch, DataType.TUPLE));
+
+    //final Schema output = udf.outputSchema(inputSchema);
+    final Schema output = udf.outputSchema(serializedSketch);
+    assertEquals(output.size(), 1);
+    assertEquals(output.getField(0).type, DataType.BAG);
+
+    final List<Schema.FieldSchema> outputFields = output.getField(0).schema.getFields();
+    assertEquals(outputFields.size(), 2);
+
+    // check high-level structure
+    assertEquals(outputFields.get(0).alias, WEIGHT_ALIAS);
+    assertEquals(outputFields.get(0).type, DataType.DOUBLE);
+    assertEquals(outputFields.get(1).alias, RECORD_ALIAS);
+    assertEquals(outputFields.get(1).type, DataType.TUPLE);
+  }
+
+  @Test
+  public void badOutputSchemaTest() throws IOException {
+    final GetVarOptSamples udf = new GetVarOptSamples();
+
+    try {
+      udf.outputSchema(null);
+    } catch (final IllegalArgumentException e) {
+      // expected
+    }
+
+    try {
+      udf.outputSchema(new Schema());
+    } catch (final IllegalArgumentException e) {
+      // expected
+    }
+
+    try {
+      final Schema wrongSchema = new Schema();
+      wrongSchema.add(new Schema.FieldSchema("field", DataType.BOOLEAN));
+      udf.outputSchema(wrongSchema);
+    } catch (final IllegalArgumentException e) {
+      // expected
+    }
+  }
+}

src/test/java/com/yahoo/sketches/pig/sampling/VarOptSamplingTest.java

@@ -23,7 +23,7 @@
 import com.yahoo.sketches.sampling.VarOptItemsSketch;
 
 public class VarOptSamplingTest {
-  private static final double EPS = 1e-10;
+  static final double EPS = 1e-10;
   private static final ArrayOfTuplesSerDe serDe_ = new ArrayOfTuplesSerDe();
 
   @Test