Close #2281 - Separate cwd commands from commands

Working directories are now set seperately from the commands so they
can later be swapped out when running linters over projects is
supported, and also better support filename mapping for running linters
on other machines in future.

test/command_callback/test_flake8_command_callback.vader

@@ -13,15 +13,13 @@ After:
 Execute(The flake8 callbacks should return the correct default values):
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
 
   " The version check should be cached.
   GivenCommandOutput []
   AssertLinter 'flake8', [
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
 
   " Try with older versions.
@@ -29,13 +27,14 @@ Execute(The flake8 callbacks should return the correct default values):
   GivenCommandOutput ['2.9.9']
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --format=default -',
+  \ ale#Escape('flake8') . ' --format=default -',
   \]
 
 Execute(The option for disabling changing directories should work):
   let g:ale_python_flake8_change_directory = 'off'
 
+  AssertLinterCwd ['', '']
+  call ale#semver#ResetVersionCache()
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
   \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
@@ -43,6 +42,7 @@ Execute(The option for disabling changing directories should work):
 
   let g:ale_python_flake8_change_directory = 0
 
+  AssertLinterCwd ['']
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
@@ -50,6 +50,7 @@ Execute(The option for disabling changing directories should work):
   " Invalid options should be considered the same as turning the setting off.
   let g:ale_python_flake8_change_directory = 'xxx'
 
+  AssertLinterCwd ['']
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
@@ -57,10 +58,11 @@ Execute(The option for disabling changing directories should work):
 Execute(The option for changing directory to project root should work):
   silent execute 'file ' . fnameescape(g:dir . '/python_paths/namespace_package_tox/namespace/foo/bar.py')
 
+  AssertLinterCwd ale#python#FindProjectRootIni(bufnr(''))
+  call ale#semver#ResetVersionCache()
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#CdString(ale#python#FindProjectRootIni(bufnr('')))
-  \   . ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
 
 Execute(The option for changing directory to file dir should work):
@@ -69,15 +71,13 @@ Execute(The option for changing directory to file dir should work):
 
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
 
   let g:ale_python_flake8_change_directory = 1
 
   AssertLinter 'flake8', [
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
   \]
 
 Execute(The flake8 command callback should let you set options):
@@ -86,8 +86,7 @@ Execute(The flake8 command callback should let you set options):
   GivenCommandOutput ['3.0.4']
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --some-option'
+  \ ale#Escape('flake8') . ' --some-option'
   \   . ' --format=default --stdin-display-name %s -',
   \]
 
@@ -95,17 +94,17 @@ Execute(The flake8 command callback should let you set options):
   GivenCommandOutput ['2.9.9']
   AssertLinter 'flake8', [
   \ ale#Escape('flake8') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   . ale#Escape('flake8') . ' --some-option --format=default -',
+  \ ale#Escape('flake8') . ' --some-option --format=default -',
   \]
 
 Execute(You should be able to set a custom executable and it should be escaped):
   let g:ale_python_flake8_executable = 'executable with spaces'
 
+  AssertLinterCwd ['%s:h', '%s:h']
+  call ale#semver#ResetVersionCache()
   AssertLinter 'executable with spaces', [
   \ ale#Escape('executable with spaces') . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   .  ale#Escape('executable with spaces')
+  \ ale#Escape('executable with spaces')
   \   . ' --format=default'
   \   . ' --stdin-display-name %s -',
   \]
@@ -119,8 +118,7 @@ Execute(The flake8 callbacks should detect virtualenv directories):
 
   AssertLinter b:executable, [
   \ ale#Escape(b:executable) . ' --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   .  ale#Escape(b:executable)
+  \ ale#Escape(b:executable)
   \   . ' --format=default'
   \   . ' --stdin-display-name %s -',
   \]
@@ -170,8 +168,7 @@ Execute(Using `python -m flake8` should be supported for running flake8):
   GivenCommandOutput ['2.9.9']
   AssertLinter 'python', [
   \ ale#Escape('python') . ' -m flake8 --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   .  ale#Escape('python')
+  \ ale#Escape('python')
   \   . ' -m flake8 --some-option --format=default -'
   \]
 
@@ -183,8 +180,7 @@ Execute(Using `python -m flake8` should be supported for running flake8):
   GivenCommandOutput ['2.9.9']
   AssertLinter 'python', [
   \ ale#Escape('python') . ' -m flake8 --version',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   .  ale#Escape('python')
+  \ ale#Escape('python')
   \   . '   -m flake8 --some-option --format=default -'
   \]
 
@@ -194,13 +190,12 @@ Execute(Setting executable to 'pipenv' should append 'run flake8'):
   " FIXME: pipenv should check the version with flake8.
   GivenCommandOutput []
   AssertLinter 'path/to/pipenv',
-  \ ale#path#BufferCdString(bufnr(''))
-  \   .  ale#Escape('path/to/pipenv') . ' run flake8 --format=default -'
+  \ ale#Escape('path/to/pipenv') . ' run flake8 --format=default -'
 
 Execute(Pipenv is detected when python_flake8_auto_pipenv is set):
   let g:ale_python_flake8_auto_pipenv = 1
   call ale#test#SetFilename('../python_fixtures/pipenv/whatever.py')
 
+  AssertLinterCwd ale#python#FindProjectRootIni(bufnr(''))
   AssertLinter 'pipenv',
-  \ ale#path#CdString(ale#python#FindProjectRootIni(bufnr('')))
-  \   . ale#Escape('pipenv') . ' run flake8 --format=default --stdin-display-name %s -'
+  \ ale#Escape('pipenv') . ' run flake8 --format=default --stdin-display-name %s -'