Add test for ALEJobStarted

test/test_alejobstarted_autocmd.vader

@@ -0,0 +1,42 @@
+Given testft (An empty file):
+
+Before:
+  let g:job_started_success = 0
+  let g:ale_run_synchronously = 1
+
+  unlet! b:ale_linted
+
+  function! TestCallback(buffer, output)
+    return []
+  endfunction
+
+  call ale#linter#Define('testft', {
+  \ 'name': 'testlinter',
+  \ 'callback': 'TestCallback',
+  \ 'executable': has('win32') ? 'cmd' : 'true',
+  \ 'command': 'true',
+  \})
+
+After:
+  let g:ale_run_synchronously = 0
+  let g:ale_buffer_info = {}
+
+  try
+    augroup! VaderTest
+  catch
+  endtry
+
+  unlet! g:job_started_success
+
+  delfunction TestCallback
+  call ale#linter#Reset()
+
+Execute(Run a lint cycle with an actual job to check for ALEJobStarted):
+  augroup VaderTest
+    autocmd!
+    autocmd User ALEJobStarted let g:job_started_success = 1
+  augroup end
+
+  call ale#Lint()
+
+  AssertEqual g:job_started_success, 1