Add new fixer: TrimWhitespace (#991)

add a new fixer: trim_whitespace

autoload/ale/fix/registry.vim

@@ -57,6 +57,11 @@ let s:default_registry = {
 \       'suggested_filetypes': [],
 \       'description': 'Remove all blank lines at the end of a file.',
 \   },
+\   'trim_whitespace': {
+\       'function': 'ale#fixers#generic#TrimWhitespace',
+\       'suggested_filetypes': [],
+\       'description': 'Remove all trailing whitespace characters at the end of every line.',
+\   },
 \   'yapf': {
 \       'function': 'ale#fixers#yapf#Fix',
 \       'suggested_filetypes': ['python'],

autoload/ale/fixers/generic.vim

@@ -10,3 +10,16 @@ function! ale#fixers#generic#RemoveTrailingBlankLines(buffer, lines) abort
 
     return a:lines[:l:end_index]
 endfunction
+
+" Remove all whitespaces at the end of lines
+function! ale#fixers#generic#TrimWhitespace(buffer, lines) abort
+    let l:index = 0
+    let l:lines_new = range(len(a:lines))
+
+    for l:line in a:lines
+        let l:lines_new[l:index] = substitute(l:line, '\s\+$', '', 'g')
+        let l:index = l:index + 1
+    endfor
+
+    return l:lines_new
+endfunction

test/fixers/test_trim_whitespace.vader

@@ -0,0 +1,28 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test/fixers')
+
+After:
+  call ale#test#RestoreDirectory()
+
+Execute(Should delete all whitespace at the end of different lines):
+  AssertEqual
+  \ [
+  \   'def foo():',
+  \   '    some_variable = this_is_a_longer_function(',
+  \   'first_argument,',
+  \   ' second_argument,',
+  \   ' third_with_function_call(',
+  \   'foo,',
+  \   ' bar,',
+  \   '))',
+  \ ],
+  \ ale#fixers#generic#TrimWhitespace(bufnr(''), [
+  \   'def foo():',     
+  \   '    some_variable = this_is_a_longer_function(', 
+  \   'first_argument,',  
+  \   ' second_argument,',   
+  \   ' third_with_function_call(',      
+  \   'foo,', 
+  \   ' bar,',   
+  \   '))',              
+  \ ])