Fix more random Windows test issues

test/sign/test_linting_sets_signs.vader

@@ -33,7 +33,7 @@ Before:
   call ale#linter#Define('foobar', {
   \ 'name': 'testlinter',
   \ 'callback': 'TestCallback',
-  \ 'executable': 'echo',
+  \ 'executable': has('win32') ? 'cmd' : 'echo',
   \ 'command': 'echo foo bar',
   \})
 

test/sign/test_sign_placement.vader

@@ -66,7 +66,7 @@ Before:
 
   call ale#linter#Define('testft', {
   \ 'name': 'x',
-  \ 'executable': 'true',
+  \ 'executable': has('win32') ? 'cmd' : 'true',
   \ 'command': 'true',
   \ 'callback': 'GenerateResults',
   \})

test/util/test_cd_string_commands.vader

@@ -7,9 +7,12 @@ After:
   unlet! g:dir
 
 Execute(CdString should output the correct command string):
-  AssertEqual 'cd ''/foo bar/baz'' && ', ale#path#CdString('/foo bar/baz')
+  " We will check that escaping is done correctly for each platform.
+  AssertEqual
+  \ has('unix') ? 'cd ''/foo bar/baz'' && ' : 'cd "/foo bar/baz" && ',
+  \ ale#path#CdString('/foo bar/baz')
 
 Execute(BufferCdString should output the correct command string):
   call ale#test#SetFilename('foo.txt')
 
-  AssertEqual 'cd ' . shellescape(g:dir) . ' && ', ale#path#BufferCdString(bufnr(''))
+  AssertEqual 'cd ' . ale#Escape(g:dir) . ' && ', ale#path#BufferCdString(bufnr(''))

test/vimrc

@@ -31,6 +31,8 @@ set foldmethod=syntax
 set foldlevelstart=10
 set foldnestmax=10
 set ttimeoutlen=0
+" The encoding must be explicitly set for tests for Windows.
+set encoding=utf-8
 
 let g:mapleader=','