Viml: Make filter and map handle null list correct

filter('v:_null_list, 'v:val') should return v:_null_list and a similar
statement should hold for map.

Changes after review

 * Test inserted in legacy test suite has been removed by reverting the commit
adding it.
 * Change the fix to tv_copy the argument before returning.
 * Readd the two tests on crashes, and modified their expected return value.
 * Move the test from 'incorrect behaviour' section to 'correct behaviour section'
 * Add analogous tests for v:_null_dict

Always copy list or dictionary to return variable

If the type of input is correct (i.e. either a list or a dictionary), this
should also be returned.

1 files changed, 8 insertions, 8 deletions

diff --git a/test/functional/eval/null_spec.lua b/test/functional/eval/null_spec.lua
index 6fd30caec9..b67158eb22 100644
--- a/test/functional/eval/null_spec.lua
+++ b/test/functional/eval/null_spec.lua
@@ -42,14 +42,6 @@ describe('NULL', function()
   describe('list', function()
     -- Incorrect behaviour
 
-    -- FIXME map() should not return 0 without error
-    null_expr_test('does not crash map()', 'map(L, "v:val")', 0, 0)
-    -- FIXME map() should not return 0 without error
-    null_expr_test('does not crash filter()', 'filter(L, "1")', 0, 0)
-    -- FIXME map() should at least return L
-    null_expr_test('makes map() return v:_null_list', 'map(L, "v:val") is# L', 0, 0)
-    -- FIXME filter() should at least return L
-    null_expr_test('makes filter() return v:_null_list', 'map(L, "1") is# L', 0, 0)
     -- FIXME add() should not return 1 at all
     null_expr_test('does not crash add()', 'add(L, 0)', 0, 1)
     null_expr_test('does not crash extend()', 'extend(L, [1])', 'E742: Cannot change value of extend() argument', 0)
@@ -111,6 +103,8 @@ describe('NULL', function()
     null_expr_test('does not crash line()', 'line(L)', 0, 0)
     null_expr_test('does not crash count()', 'count(L, 1)', 0, 0)
     null_expr_test('does not crash cursor()', 'cursor(L)', 'E474: Invalid argument', -1)
+    null_expr_test('does not crash map()', 'map(L, "v:val")', 0, {})
+    null_expr_test('does not crash filter()', 'filter(L, "1")', 0, {})
     null_expr_test('is empty', 'empty(L)', 0, 1)
     null_expr_test('does not crash get()', 'get(L, 1, 10)', 0, 10)
     null_expr_test('has zero length', 'len(L)', 0, 0)
@@ -126,6 +120,8 @@ describe('NULL', function()
     null_expr_test('is equal to itself', 'L == L', 0, 1)
     null_expr_test('is not not equal to itself', 'L != L', 0, 0)
     null_expr_test('counts correctly', 'count([L], L)', 0, 1)
+    null_expr_test('makes map() return v:_null_list', 'map(L, "v:val") is# L', 0, 1)
+    null_expr_test('makes filter() return v:_null_list', 'filter(L, "1") is# L', 0, 1)
   end)
   describe('dict', function()
     it('does not crash when indexing NULL dict', function()
@@ -134,5 +130,9 @@ describe('NULL', function()
     end)
     null_expr_test('makes extend error out', 'extend(D, {})', 'E742: Cannot change value of extend() argument', 0)
     null_expr_test('makes extend do nothing', 'extend({1: 2}, D)', 0, {['1']=2})
+    null_expr_test('does not crash map()', 'map(D, "v:val")', 0, {})
+    null_expr_test('does not crash filter()', 'filter(D, "1")', 0, {})
+    null_expr_test('makes map() return v:_null_dict', 'map(D, "v:val") is# D', 0, 1)
+    null_expr_test('makes filter() return v:_null_dict', 'filter(D, "1") is# D', 0, 1)
   end)
 end)