Fix issues with running individual tests, and get the Vim tests to run on certain machines again

test/handler/test_jscs_handler.vader

@@ -1,3 +1,8 @@
+Before:
+  runtime ale_linters/javascript/jscs.vim
+
+After:
+  call ale#linter#Reset()
 
 Execute(jscs should parse lines correctly):
   AssertEqual

test/test_find_nearest_directory.vader

@@ -1,15 +1,17 @@
-Execute(Open a file some directory down):
-  silent! cd /testplugin/test
-  :e! top/middle/bottom/dummy.txt
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+
+After:
+  call ale#test#RestoreDirectory()
+
+Execute(We should be able to find a directory some directory down):
+  call ale#test#SetFilename('top/middle/bottom/dummy.txt')
 
-Then(We should be able to find the right directory):
   AssertEqual
   \ expand('%:p:h:h:h:h') . '/top/ale-special-directory-name-dont-use-this-please/',
   \ ale#path#FindNearestDirectory(bufnr('%'), 'ale-special-directory-name-dont-use-this-please')
 
-Execute(Do nothing):
-
-Then(We shouldn't find anything for files which don't match):
+Execute(We shouldn't find anything for files which don't match):
   AssertEqual
   \ '',
   \ ale#path#FindNearestDirectory(bufnr('%'), 'ale-this-should-never-match-anything')

test/test_nearest_file_search.vader

@@ -1,11 +1,13 @@
-Execute(Open a file some directory down):
-  silent! cd /testplugin/test
-  :e! top/middle/bottom/dummy.txt
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+
+After:
+  call ale#test#RestoreDirectory()
+
+Execute(We should be able to find a configuration file further up):
+  call ale#test#SetFilename('top/middle/bottom/dummy.txt')
 
-Then(We should be able to find a configuration file further up):
   AssertEqual expand('%:p:h:h:h:h') . '/top/example.ini', ale#path#FindNearestFile(bufnr('%'), 'example.ini')
 
-Execute(Do nothing):
-
-Then(We shouldn't find anything for files which don't match):
+Execute(We shouldn't find anything for files which don't match):
   AssertEqual '', ale#path#FindNearestFile(bufnr('%'), 'cantfindthis')

test/test_resolve_local_path.vader

@@ -1,15 +1,17 @@
-Execute(Open a file some directory down):
-  silent! cd /testplugin/test
-  :e! top/middle/bottom/dummy.txt
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+
+After:
+  call ale#test#RestoreDirectory()
+
+Execute(We should be able to find the local version of a file):
+  call ale#test#SetFilename('top/middle/bottom/dummy.txt')
 
-Then(We should be able to find the local version of a file):
   AssertEqual
   \ expand('%:p:h:h:h:h') . '/top/example.ini',
   \  ale#path#ResolveLocalPath(bufnr('%'), 'example.ini', '/global/config.ini')
 
-Execute(Do nothing):
-
-Then(We shouldn't find anything for files which don't match):
+Execute(We shouldn't find anything for files which don't match):
   AssertEqual
   \ '/global/config.ini',
   \  ale#path#ResolveLocalPath(bufnr('%'), 'missing.ini', '/global/config.ini')

test/test_sandbox_execution.vader

@@ -47,6 +47,12 @@ Execute(ALE shouldn't blow up when run from a sandbox):
   sandbox call ale#Lint()
 
 Execute(ALE shouldn't blow up if file cleanup happens in a sandbox):
+  " Make a call to an engine function first, so the function will be defined
+  " before we make the sandbox call.
+  "
+  " You are not allowed to define any functions in the sandbox.
+  call ale#engine#InitBufferInfo(3)
+
   let g:ale_buffer_info[3] = {
   \ 'temporary_file_list': ['/tmp/foo'],
   \ 'temporary_directory_list': ['/tmp/bar'],