Fix tuple equality with null values (#327)

Previously, if tuples had the same fields, and at least one field had a null value on one tuple and a non-null value on the other, then:
* if the null/non-null field came after a field with different values, it returned false (which is correct)
* if the null/non-null field came before a field with different values, it returned null (which is incorrect)

Now it will return the correct answer regardless of where the null/non-null field is.

Co-authored-by: hossenlopp <hossenlopp@mitre.org>

Author: cmoesel

examples/browser/cql4browsers.js

@@ -8755,14 +8755,15 @@ function deepCompareKeysAndValues(a, b, comparisonFunction) {
             const comparisonResult = comparisonFunction(a[key], b[key]);
             if (comparisonResult === null) {
                 shouldReturnNull = true;
+                return true;
             }
             return comparisonResult;
         });
     }
     else {
         finalComparisonResult = false;
     }
-    if (shouldReturnNull) {
+    if (finalComparisonResult && shouldReturnNull) {
         return null;
     }
     return finalComparisonResult;

src/util/comparison.ts

@@ -165,14 +165,15 @@ function deepCompareKeysAndValues(a: any, b: any, comparisonFunction: any) {
       const comparisonResult = comparisonFunction(a[key], b[key]);
       if (comparisonResult === null) {
         shouldReturnNull = true;
+        return true;
       }
       return comparisonResult;
     });
   } else {
     finalComparisonResult = false;
   }
 
-  if (shouldReturnNull) {
+  if (finalComparisonResult && shouldReturnNull) {
     return null;
   }
   return finalComparisonResult;

test/elm/comparison/comparison-test.ts

@@ -36,6 +36,12 @@ describe('Equal', () => {
 
   it('should identify uncertian tuples with same fields but one has a null field', async function () {
     should(await this.uncertTuplesWithNullFieldOnOne.exec(this.ctx)).be.null();
+    should(await this.uncertTuplesWithNullFieldOnFirstOne.exec(this.ctx)).be.null();
+  });
+
+  it('should identify unequal tuples with different values but one has a null field', async function () {
+    should(await this.uneqTuplesWithNullFieldOnOne.exec(this.ctx)).be.false();
+    should(await this.uneqTuplesWithNullFieldOnFirstOne.exec(this.ctx)).be.false();
   });
 
   it('should identify equal/unequal DateTimes in same timezone', async function () {

test/elm/comparison/data.cql

@@ -7,6 +7,9 @@ define UneqTuples: Tuple{a: 1, b: Tuple{c: 1}} = Tuple{a: 1, b: Tuple{c: -1}}
 define EqTuplesWithNullFields: Tuple{a: 'Hello', b: null} = Tuple{a: 'Hello', b: null}
 define UneqTuplesWithNullFields: Tuple{a: 'Hello', b: null} = Tuple{a: 'Goodbye', b: null}
 define UncertTuplesWithNullFieldOnOne: Tuple{a: 'Hello', b: null} = Tuple{a: 'Hello', b: 'null'}
+define UncertTuplesWithNullFieldOnFirstOne: Tuple{a: null, b: 'Goodbye'} = Tuple{a: 'Hello', b: 'Goodbye'}
+define UneqTuplesWithNullFieldOnOne: Tuple{a: 'Hello', b: null} = Tuple{a: 'Goodbye', b: 'null'}
+define UneqTuplesWithNullFieldOnFirstOne: Tuple{a: null, b: 'Hello'} = Tuple{a: 'null', b: 'Goodbye'}
 define EqDateTimes: DateTime(2000, 3, 15, 13, 30, 25, 200, +1.0) = DateTime(2000, 3, 15, 13, 30, 25, 200, +1.0)
 define UneqDateTimes: DateTime(2000, 3, 15, 13, 30, 25, 200, +1.0) = DateTime(2000, 3, 15, 13, 30, 25, 201, +1.0)
 define EqDateTimesTZ: DateTime(2000, 3, 15, 23, 30, 25, 200, +1.0) = DateTime(2000, 3, 16, 2, 30, 25, 200, +4.0)