Fix #625 Ignore Perl errors from other files

ale_linters/perl/perl.vim

@@ -20,17 +20,21 @@ endfunction
 function! ale_linters#perl#perl#Handle(buffer, lines) abort
     let l:pattern = '\(.\+\) at \(.\+\) line \(\d\+\)'
     let l:output = []
+    let l:basename = expand('#' . a:buffer . ':t')
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:line = l:match[3]
         let l:text = l:match[1]
         let l:type = 'E'
 
-        call add(l:output, {
-        \   'lnum': l:line,
-        \   'text': l:text,
-        \   'type': l:type,
-        \})
+        if l:match[2][-len(l:basename):] ==# l:basename
+        \&& l:text !=# 'BEGIN failed--compilation aborted'
+            call add(l:output, {
+            \   'lnum': l:line,
+            \   'text': l:text,
+            \   'type': l:type,
+            \})
+        endif
     endfor
 
     return l:output

test/handler/test_perl_handler.vader

@@ -0,0 +1,25 @@
+Before:
+  " Switch to the test rails directory.
+  let b:path = getcwd()
+  silent! cd /testplugin/test/handler
+
+  runtime ale_linters/perl/perl.vim
+
+After:
+  silent! 'cd ' . fnameescape(b:path)
+  unlet! b:path
+
+  call ale#linter#Reset()
+
+Execute(The Perl linter should ignore errors from other files):
+  silent! noautocmd file bar.pl
+
+  AssertEqual
+  \ [
+  \    {'lnum': '2', 'type': 'E', 'text': 'Compilation failed in require'},
+  \ ],
+  \ ale_linters#perl#perl#Handle(bufnr(''), [
+  \   'syntax error at ' . b:path . '/foo.pm line 4, near "aklsdfjmy "',
+  \   'Compilation failed in require at ' . b:path . '/bar.pl line 2.',
+  \   'BEGIN failed--compilation aborted at ' . b:path . '/bar.pl line 2.',
+  \ ])