Use iskeyword rather than isident, and add a test we respect it.

Author: Julian

autoload/textobj/variable_segment.vim

@@ -1,5 +1,5 @@
 function! s:select(object_type, right_boundary)
-    let left_boundaries = ['_\+\i', '\<', '\l\u', '\u\u\ze\l', '\a\d', '\d\a']
+    let left_boundaries = ['_\+\k', '\<', '\l\u', '\u\u\ze\l', '\a\d', '\d\a']
     call search(join(left_boundaries, '\|'), 'bce')
     let start_position = getpos('.')
 
@@ -19,12 +19,12 @@ function! s:select(object_type, right_boundary)
 endfunction
 
 function! s:select_a()
-    let right_boundaries = ['_', '\l\u', '\u\u\l', '\a\d', '\d\a', '\i\>']
+    let right_boundaries = ['_', '\l\u', '\u\u\l', '\a\d', '\d\a', '\k\>']
     let right_boundary = join(right_boundaries, '\|')
     let [type, start_position, end_position] = s:select('a', right_boundary)
     let [_, start_line, start_column, _] = start_position
 
-    call search('\i\>', 'c')
+    call search('\k\>', 'c')
     if end_position == getpos('.') &&
      \ getline(start_line)[start_column - 2] =~# '_'
         let start_position[2] -= 1
@@ -49,7 +49,7 @@ function! s:select_a()
 endfunction
 
 function! s:select_i()
-    let right_boundaries = ['\i_', '\l\u', '\u\u\l', '\a\d', '\d\a', '\i\>']
+    let right_boundaries = ['\k_', '\l\u', '\u\u\l', '\a\d', '\d\a', '\k\>']
     return s:select('i', join(right_boundaries, '\|'))
 endfunction
 

t/variable-segment.vim

@@ -205,6 +205,16 @@ describe 'iv'
         normal civone
         Expect getline(1) == 'one another'
     end
+
+    it 'respects &iskeyword'
+        let original = &iskeyword 
+        set iskeyword=a-z,_,'
+        put! = 'bag_of_spam'' stuff'
+        normal! 9|
+        normal civeggs_n'
+        Expect getline(1) == "bag_of_eggs_n' stuff"
+        let &iskeyword = original
+    end
 end
 
 
@@ -404,6 +414,7 @@ describe 'av'
         normal dav
         Expect getline(1) == 'foo bazQuux'
     end
+
     it 'selects leading small camels and swaps case even with tildeop'
         set tildeop  " Vim default is notildeop
         put! = 'fooBarQuux'
@@ -413,4 +424,14 @@ describe 'av'
         Expect &tildeop == 1
         set notildeop
     end
+
+    it 'respects &iskeyword'
+        let original = &iskeyword 
+        set iskeyword=a-z,_,'
+        put! = 'bag_of_spam'' stuff'
+        normal! 9|
+        normal dav
+        Expect getline(1) == "bag_of stuff"
+        let &iskeyword = original
+    end
 end