Add support for dot-seperate linters, improve linter tests

This PR first and formost implements support for dot-seperate filetypes,
a very trivial change.

This closes #132

But more importantly, this PR vastly improves the test quality for
`ale#linter#Get`. It enables us to reset the state of ale's internal
linter cache, to facilitate better testing, as well as making use of
mocked linters instead of depending on linters on disk (which may
change). In addition, a dummy linter is defined to test the autoloading
behavior.

Header guards were removed from all linters as:

* A: ale won't try and load linters if they already exist in memory
* B: we can't reset state for testing if they can't be loaded again

1 files changed, 49 insertions, 38 deletions

diff --git a/autoload/ale/linter.vim b/autoload/ale/linter.vim
index e6dc9b16..9f4eb798 100644
--- a/autoload/ale/linter.vim
+++ b/autoload/ale/linter.vim
@@ -7,7 +7,6 @@ let s:linters = {}
 " Default filetype aliaes.
 " The user defined aliases will be merged with this Dictionary.
 let s:default_ale_linter_aliases = {
-\   'javascript.jsx': 'javascript',
 \   'zsh': 'sh',
 \   'csh': 'sh',
 \}
@@ -19,6 +18,11 @@ let s:default_ale_linters = {
 \   'csh': ['shell'],
 \}
 
+" Testing/debugging helper to unload all linters.
+function! ale#linter#Reset() abort
+    let s:linters = {}
+endfunction
+
 function! ale#linter#Define(filetype, linter) abort
     if !has_key(s:linters, a:filetype)
         let s:linters[a:filetype] = []
@@ -74,45 +78,52 @@ function! s:LoadLinters(filetype) abort
     return s:linters[a:filetype]
 endfunction
 
-function! ale#linter#Get(original_filetype) abort
-    " Try and get an aliased file type either from the user's Dictionary, or
-    " our default Dictionary, otherwise use the filetype as-is.
-    let l:filetype = get(
-    \   g:ale_linter_aliases,
-    \   a:original_filetype,
-    \   get(
-    \       s:default_ale_linter_aliases,
-    \       a:original_filetype,
-    \       a:original_filetype
-    \   )
-    \)
-
-    " Try and get a list of linters to run, using the original file type,
-    " not the aliased filetype. We have some linters to limit by default,
-    " and users may define their own list of linters to run.
-    let l:linter_names = get(
-    \   g:ale_linters,
-    \   a:original_filetype,
-    \   get(
-    \       s:default_ale_linters,
-    \       a:original_filetype,
-    \       'all'
-    \   )
-    \)
-
-    let l:all_linters = s:LoadLinters(l:filetype)
+function! ale#linter#Get(original_filetypes) abort
     let l:combined_linters = []
 
-    if type(l:linter_names) == type('') && l:linter_names ==# 'all'
-        let l:combined_linters = l:all_linters
-    elseif type(l:linter_names) == type([])
-        " Select only the linters we or the user has specified.
-        for l:linter in l:all_linters
-            if index(l:linter_names, l:linter.name) >= 0
-                call add(l:combined_linters, l:linter)
-            endif
-        endfor
-    endif
+    " Handle dot-seperated filetypes.
+    for l:original_filetype in split(a:original_filetypes, '\.')
+        " Try and get an aliased file type either from the user's Dictionary, or
+        " our default Dictionary, otherwise use the filetype as-is.
+        let l:filetype = get(
+        \   g:ale_linter_aliases,
+        \   l:original_filetype,
+        \   get(
+        \       s:default_ale_linter_aliases,
+        \       l:original_filetype,
+        \       l:original_filetype
+        \   )
+        \)
+
+        " Try and get a list of linters to run, using the original file type,
+        " not the aliased filetype. We have some linters to limit by default,
+        " and users may define their own list of linters to run.
+        let l:linter_names = get(
+        \   g:ale_linters,
+        \   l:original_filetype,
+        \   get(
+        \       s:default_ale_linters,
+        \       l:original_filetype,
+        \       'all'
+        \   )
+        \)
+
+        let l:all_linters = s:LoadLinters(l:filetype)
+        let l:filetype_linters = []
+
+        if type(l:linter_names) == type('') && l:linter_names ==# 'all'
+            let l:filetype_linters = l:all_linters
+        elseif type(l:linter_names) == type([])
+            " Select only the linters we or the user has specified.
+            for l:linter in l:all_linters
+                if index(l:linter_names, l:linter.name) >= 0
+                    call add(l:filetype_linters, l:linter)
+                endif
+            endfor
+        endif
+
+        call extend(l:combined_linters, l:filetype_linters)
+    endfor
 
     return l:combined_linters
 endfunction