fix: stable sort for undefined keys, fixes #191

test/integration/builtin/filters/math.ts

@@ -89,6 +89,19 @@ describe('filters/math', function () {
       const html = await l.parseAndRender(src, { students })
       expect(html).to.equal('bob alice carol')
     })
+    it('should be stable when it comes to undefined props', async () => {
+      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
+      const students = [
+        { name: 'bob' },
+        { name: 'alice', age: 2 },
+        { name: 'amber' },
+        { name: 'watson' },
+        { name: 'michael' },
+        { name: 'charlie' }
+      ]
+      const html = await l.parseAndRender(src, { students })
+      expect(html).to.equal('alice bob amber watson michael charlie')
+    })
     it('should tolerate undefined props', async () => {
       const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
       const students = [

test/unit/util/underscore.ts

@@ -108,4 +108,21 @@ describe('util/underscore', function () {
       expect(_.changeCase('FOOA')).to.equal('fooa')
     })
   })
+  describe('.caseInsensitiveCompare()', function () {
+    it('should "foo" > "bar"', () => {
+      expect(_.caseInsensitiveCompare('foo', 'bar')).to.equal(1)
+    })
+    it('should "foo" < null', () => {
+      expect(_.caseInsensitiveCompare('foo', null)).to.equal(-1)
+    })
+    it('should null > "foo"', () => {
+      expect(_.caseInsensitiveCompare(null, 'foo')).to.equal(1)
+    })
+    it('should -1 < 0', () => {
+      expect(_.caseInsensitiveCompare(-1, 0)).to.equal(-1)
+    })
+    it('should 1 > 0', () => {
+      expect(_.caseInsensitiveCompare(1, 0)).to.equal(1)
+    })
+  })
 })