Treat null and empty string as different values when doing transforms

main/src/com/google/refine/expr/ExpressionUtils.java

@@ -125,11 +125,9 @@ public class ExpressionUtils {
 
     static public boolean sameValue(Object v1, Object v2) {
         if (v1 == null) {
-            return (v2 == null)
-                    || (v2 instanceof String && ((String) v2).length() == 0);
+            return (v2 == null) ;
         } else if (v2 == null) {
-            return (v1 == null)
-                    || (v1 instanceof String && ((String) v1).length() == 0);
+            return (v1 == null);
         } else {
             return v1.equals(v2);
         }

main/tests/server/src/com/google/refine/tests/expr/ExpressionUtilsTests.java

@@ -0,0 +1,96 @@
+/*
+
+Copyright 2017, Owen Stephens
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+    * Neither the name of the copyright holder nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,           
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY           
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+ 
+package com.google.refine.tests.expr.functions;
+
+import java.util.Properties;
+
+import org.slf4j.LoggerFactory;
+import org.testng.Assert;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.Test;
+
+import com.google.refine.browsing.Engine;
+import com.google.refine.expr.ExpressionUtils;
+import com.google.refine.model.Project;
+import com.google.refine.tests.RefineTest;
+
+
+public class ExpressionUtilsTests extends RefineTest {
+
+    Project project;
+    Properties bindings;
+    
+    @Override
+    @BeforeTest
+    public void init() {
+        logger = LoggerFactory.getLogger(this.getClass());
+    }
+
+
+    @BeforeMethod
+    public void SetUp() {
+        project = new Project();
+        bindings = ExpressionUtils.createBindings(project);
+    }
+
+    @AfterMethod
+    public void TearDown() {
+        project = null;
+        bindings = null;
+    }
+
+    // -----------------tests------------
+
+    @Test
+    public void testSameValueTrue() {
+        Assert.assertTrue(ExpressionUtils.sameValue(null,null));
+        Assert.assertTrue(ExpressionUtils.sameValue("",""));
+        Assert.assertTrue(ExpressionUtils.sameValue("one","one"));
+        Assert.assertTrue(ExpressionUtils.sameValue(1,1));
+        Assert.assertTrue(ExpressionUtils.sameValue(1.0,1.00));
+        Assert.assertTrue(ExpressionUtils.sameValue(true,true));
+    }
+
+    @Test
+    public void testSameValueFalse() {
+        Assert.assertFalse(ExpressionUtils.sameValue("",null));
+        Assert.assertFalse(ExpressionUtils.sameValue(null,""));
+        Assert.assertFalse(ExpressionUtils.sameValue("one","two"));
+        Assert.assertFalse(ExpressionUtils.sameValue(1,2));
+        Assert.assertFalse(ExpressionUtils.sameValue(1,1.0));
+        Assert.assertFalse(ExpressionUtils.sameValue(true,false));
+    }
+}