PLUGIN-1925: Refactor logic for edge case and unit tests

Author: sgarg-CS

database-commons/src/main/java/io/cdap/plugin/db/source/CustomBigDecimalSplitter.java

@@ -37,12 +37,6 @@ public class CustomBigDecimalSplitter extends BigDecimalSplitter {
    */
   @Override
   protected BigDecimal tryDivide(BigDecimal numerator, BigDecimal denominator) {
-    if (denominator.compareTo(numerator) == 0) {
-      throw new ArithmeticException("Numerator and Denominator are equal in splitter");
-    }
-    if (denominator.compareTo(BigDecimal.ZERO) == 0) {
-      throw new ArithmeticException("Division by zero in splitter");
-    }
     // Derive scale from numerator/denominator + buffer
     int effectiveScale = Math.max(numerator.scale(), denominator.scale()) + SCALE_BUFFER;
     return numerator.divide(denominator, effectiveScale, RoundingMode.HALF_UP);

database-commons/src/test/java/io/cdap/plugin/db/source/CustomBigDecimalSplitterTest.java

@@ -16,11 +16,21 @@
 
 package io.cdap.plugin.db.source;
 
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.mapreduce.InputSplit;
+import org.apache.hadoop.mapreduce.lib.db.BigDecimalSplitter;
 import org.junit.Test;
+
 import java.math.BigDecimal;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.List;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 /**
  * Test class for {@link CustomBigDecimalSplitter}
@@ -49,9 +59,40 @@ public void testDivisionByZero() {
   }
 
   @Test
-  public void testZeroNumerator() {
+  public void testDivisionWithZeroNumerator() {
     // when minVal == maxVal
     BigDecimal result = splitter.tryDivide(BigDecimal.ZERO, BigDecimal.ONE);
     assertEquals(0, result.compareTo(BigDecimal.ZERO));
   }
+
+  @Test
+  public void testSplits() throws SQLException {
+    BigDecimal minVal = BigDecimal.valueOf(1);
+    BigDecimal maxVal = BigDecimal.valueOf(2);
+    int numSplits = 4;
+    ResultSet resultSet = mock(ResultSet.class);
+    Configuration conf = mock(Configuration.class);
+    when(conf.getInt("mapreduce.job.maps", 1)).thenReturn(numSplits);
+    when(resultSet.getBigDecimal(1)).thenReturn(minVal);
+    when(resultSet.getBigDecimal(2)).thenReturn(maxVal);
+    BigDecimalSplitter bigDecimalSplitter = new CustomBigDecimalSplitter();
+    List<InputSplit> actualSplits = bigDecimalSplitter.split(conf, resultSet, "id");
+    assertEquals(numSplits, actualSplits.size());
+  }
+
+  @Test
+  public void testSplitsWithMinValueEqualToMaxValue() throws SQLException {
+    // when minVal == maxVal
+    BigDecimal minVal = BigDecimal.valueOf(1);
+    BigDecimal maxVal = BigDecimal.valueOf(1);
+    int numSplits = 1;
+    ResultSet resultSet = mock(ResultSet.class);
+    Configuration conf = mock(Configuration.class);
+    when(conf.getInt("mapreduce.job.maps", 1)).thenReturn(numSplits);
+    when(resultSet.getBigDecimal(1)).thenReturn(minVal);
+    when(resultSet.getBigDecimal(2)).thenReturn(maxVal);
+    BigDecimalSplitter bigDecimalSplitter = new CustomBigDecimalSplitter();
+    List<InputSplit> actualSplits = bigDecimalSplitter.split(conf, resultSet, "id");
+    assertEquals(numSplits, actualSplits.size());
+  }
 }