Add in unit test to lock in the fix for dev_core_2272

tests/phpunit/CRM/Export/BAO/ExportTest.php

@@ -664,6 +664,40 @@ public function testExportRelationshipsMergeToHousehold($includeHouseHold) {
     $this->assertEquals('household sauce', $row['Contact Source']);
   }
 
+  /**
+   * Test exporting contacts merged into households
+   *
+   * This is to ensure that CRM-13995 remains fixed.
+   *
+   * @dataProvider getBooleanDataProvider
+   *
+   * @param bool $includeHouseHold
+   *
+   * @throws CRM_Core_Exception
+   * @throws \League\Csv\Exception
+   */
+  public function testExportMergeToHousehold($includeHouseHold) {
+    list($householdID, $houseHoldTypeID) = $this->setUpHousehold();
+
+    if ($includeHouseHold) {
+      $this->contactIDs[] = $householdID;
+    }
+    $selectedFields = [
+      ['contact_type' => 'Individual', 'name' => 'contact_source', 'location_type_id' => ''],
+    ];
+    $this->doExportTest([
+      'ids' => $this->contactIDs,
+      'fields' => $selectedFields,
+      'mergeSameHousehold' => TRUE,
+      'componentTable' => 'civicrm_contact',
+      'componentClause' => 'contact_a.id IN (' . implode(',', $this->contactIDs) . ')',
+    ]);
+    $row = $this->csv->fetchOne();
+    $this->assertCount(1, $this->csv);
+    $this->assertEquals($householdID, $row['Household ID']);
+
+  }
+
   /**
    * Test exporting relationships.
    *