fix(filterFilter): fix matching against null/undefined

Included fixes:

* Do not convert `null`/`undefined` to strings for substring matching in
  non-strict comparison mode. Prevents `null`/`undefined` from being matched
  against e.g. 'u'.
* Let `null` (as a top-level filter expression) match "deeply" (as do booleans,
  numbers and strings).
  E.g. let `filterFilter(arr, null)` match an item like `{someProp: null}`.

Fixes #11573

Closes #11617

Author: gkalpak

src/ng/filter/filter.js

@@ -126,14 +126,16 @@ function filterFilter() {
   return function(array, expression, comparator) {
     if (!isArray(array)) return array;
 
+    var expressionType = (expression !== null) ? typeof expression : 'null';
     var predicateFn;
     var matchAgainstAnyProp;
 
-    switch (typeof expression) {
+    switch (expressionType) {
       case 'function':
         predicateFn = expression;
         break;
       case 'boolean':
+      case 'null':
       case 'number':
       case 'string':
         matchAgainstAnyProp = true;
@@ -159,6 +161,14 @@ function createPredicateFn(expression, comparator, matchAgainstAnyProp) {
     comparator = equals;
   } else if (!isFunction(comparator)) {
     comparator = function(actual, expected) {
+      if (isUndefined(actual)) {
+        // No substring matching against `undefined`
+        return false;
+      }
+      if ((actual === null) || (expected === null)) {
+        // No substring matching against `null`; only match against `null`
+        return actual === expected;
+      }
       if (isObject(actual) || isObject(expected)) {
         // Prevent an object to be considered equal to a string like `'[object'`
         return false;

test/ng/filter/filterSpec.js

@@ -435,8 +435,59 @@ describe('Filter: filter', function() {
   });
 
 
+  it('should match `null` against `null` only', function() {
+    var items = [
+      {value: null},
+      {value: undefined},
+      {value: true},
+      {value: false},
+      {value: NaN},
+      {value: 42},
+      {value: 'null'},
+      {value: 'test'},
+      {value: {}},
+      {value: new Date()}
+    ];
+    var flt;
+
+    flt = null;
+    expect(filter(items, flt).length).toBe(1);
+    expect(filter(items, flt)[0]).toBe(items[0]);
+
+    flt = {value: null};
+    expect(filter(items, flt).length).toBe(1);
+    expect(filter(items, flt)[0]).toBe(items[0]);
+
+    flt = {value: undefined};
+    expect(filter(items, flt).length).toBe(items.length);
+
+    flt = {value: NaN};
+    expect(includes(filter(items, flt), items[0])).toBeFalsy();
+
+    flt = {value: false};
+    expect(includes(filter(items, flt), items[0])).toBeFalsy();
+
+    flt = '';
+    expect(includes(filter(items, flt), items[0])).toBeFalsy();
+
+    flt = {value: 'null'};
+    expect(includes(filter(items, flt), items[0])).toBeFalsy();
+  });
+
+
   describe('should support comparator', function() {
 
+    it('not convert `null` or `undefined` to string in non-strict comparison', function() {
+      var items = [
+        {value: null},
+        {value: undefined}
+      ];
+      var flt = {value: 'u'};
+
+      expect(filter(items, flt).length).toBe(0);
+    });
+
+
     it('not consider `object === "[object Object]"` in non-strict comparison', function() {
       var items = [{test: {}}];
       var expr = '[object';