diff --git a/vlib/builtin/array_test.v b/vlib/builtin/array_test.v
index 61db9f1245..fa8b431d68 100644
--- a/vlib/builtin/array_test.v
+++ b/vlib/builtin/array_test.v
@@ -452,6 +452,8 @@ fn test_in() {
 	assert 3 in a
 	assert !(4 in a)
 	assert !(0 in a)
+	assert 0 !in a
+	assert 4 !in a
 }
 
 fn sum(prev int, curr int) int {
@@ -490,6 +492,13 @@ fn test_filter() {
 	d := c.filter(it.len > 1)
 	assert d[0] == 'is'
 	assert d[1] == 'awesome'
+	////////
+	arr :=[1,2,3,4,5,6,7,8,9,10]
+	println(arr.filter(it % 2 == 0 || it % 3 == 0))
+	assert true
+	assert [1,2,3].len == 3
+	// TODO
+	//assert arr.filter(arr % 2).len == 5
 }
 
 fn test_map() {