patch 7.4.2121
Problem: No easy way to check if lambda and closure are supported.
Solution: Add the +lambda feature.
diff --git a/src/testdir/test_lambda.vim b/src/testdir/test_lambda.vim
index 9eb34e4..5118738 100644
--- a/src/testdir/test_lambda.vim
+++ b/src/testdir/test_lambda.vim
@@ -1,5 +1,9 @@
" Test for lambda and closure
+function! Test_lambda_feature()
+ call assert_equal(1, has('lambda'))
+endfunction
+
function! Test_lambda_with_filter()
let s:x = 2
call assert_equal([2, 3], filter([1, 2, 3], {i, v -> v >= s:x}))