patch 8.2.1946: sort() with NULL string not tested

Problem:    sort() with NULL string not tested.
Solution:   Add a test.  use v:collate. (Dominique Pellé, closes #7247)

Author: brammool

src/testdir/test_sort.vim

@@ -24,21 +24,25 @@ func Test_sort_strings()
 
   " This does not appear to work correctly on Mac.
   if !has('mac')
-    let lc = execute('language collate')
     " With the following locales, the accentuated letters are ordered
     " similarly to the non-accentuated letters...
-    if lc =~? '"\(en\|es\|de\|fr\|it\|nl\).*\.utf-\?8"'
+    if v:collate =~? '^\(en\|es\|de\|fr\|it\|nl\).*\.utf-\?8$'
       call assert_equal(['a', 'A', 'ä', 'Ä', 'o', 'O', 'ô', 'Ô', 'œ', 'œ', 'p', 'P'],
       \            sort(['A', 'a', 'o', 'O', 'œ', 'œ', 'p', 'P', 'Ä', 'ä', 'ô', 'Ô'], 'l'))
     " ... whereas with a Swedish locale, the accentuated letters are ordered
     " after Z.
-    elseif lc =~? '"sv.*utf-\?8"'
+    elseif v:collate =~? '^sv.*utf-\?8$'
       call assert_equal(['a', 'A', 'o', 'O', 'p', 'P', 'ä', 'Ä', 'œ', 'œ', 'ô', 'Ô'],
       \            sort(['A', 'a', 'o', 'O', 'œ', 'œ', 'p', 'P', 'Ä', 'ä', 'ô', 'Ô'], 'l'))
     endif
   endif
 endfunc
 
+func Test_sort_null_string()
+  " null strings are sorted as empty strings.
+  call assert_equal(['', 'a', 'b'], sort(['b', test_null_string(), 'a']))
+endfunc
+
 func Test_sort_numeric()
   call assert_equal([1, 2, 3], sort([3, 2, 1], 'n'))
   call assert_equal([3, 13, 28], sort([13, 28, 3], 'n'))
@@ -1229,8 +1233,7 @@ func Test_sort_cmd()
     " With the following locales, the accentuated letters are ordered
     " similarly to the non-accentuated letters.
     " This does not appear to work on Mac
-    let lc = execute('language collate')
-    if lc =~? '"\(en\|es\|de\|fr\|it\|nl\).*\.utf-\?8"' && !has('mac')
+    if v:collate =~? '^\(en\|es\|de\|fr\|it\|nl\).*\.utf-\?8$' && !has('mac')
       let tests += [
 	\ {
 	\    'name' : 'sort with locale',

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1946,
 /**/
     1945,
 /**/