toBoolean() might return null #50

Author: aeberhart

src/main/java/com/dashjoin/jsonata/Functions.java

@@ -1607,7 +1607,8 @@ public static List filter(List arr, Object func) throws Throwable {
             var func_args = hofFuncArgs(func, entry, i, arr);
             // invoke func
             var res = funcApply(func, func_args);
-            if (toBoolean(res)) {
+            var booledValue = toBoolean(res);
+            if (booledValue == null ? false : booledValue) {
                 result.add(entry);
             }
         }
@@ -1638,7 +1639,8 @@ public static Object single(List arr, Object func) throws Throwable {
                 var func_args = hofFuncArgs(func, entry, i, arr);
                 // invoke func
                 var res = funcApply(func, func_args);
-                positiveResult = toBoolean(res);
+                var booledValue = toBoolean(res);
+                positiveResult = booledValue == null ? false : booledValue;
             }
             if (positiveResult) {
                 if(!hasFoundMatch) {

src/test/java/com/dashjoin/jsonata/NullSafetyTest.java

@@ -1,7 +1,7 @@
 package com.dashjoin.jsonata;
 
 import static com.dashjoin.jsonata.Jsonata.jsonata;
-
+import java.util.Arrays;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
@@ -36,4 +36,21 @@ public void testNullSafety() {
         res = jsonata("$spread(null)").evaluate(null);
         Assertions.assertEquals(null, res);
     }
+    
+    @Test
+    public void testFilterNull() {
+        var x = Jsonata.jsonata("$filter($, function($v, $i, $a){$v})").evaluate(Arrays.asList(1, null));
+        Assertions.assertEquals(1, x);
+    }
+    
+    @Test
+    public void testNotNull() {
+        Assertions.assertNull(Jsonata.jsonata("$not($)").evaluate(null));
+    }
+    
+    @Test
+    public void testSingleNull() {
+        var x = Jsonata.jsonata("$single($, function($v, $i, $a){ $v })").evaluate(Arrays.asList(null, 1));
+        Assertions.assertEquals(1, x);
+    }
 }