Simplify the code for most linters and tests with closures

test/command_callback/test_phpcs_command_callback.vader

@@ -0,0 +1,29 @@
+Before:
+  call ale#assert#SetUpLinterTest('php', 'phpcs')
+
+After:
+  unlet! g:executable
+
+  call ale#assert#TearDownLinterTest()
+
+Execute(The local phpcs executable should be used):
+  call ale#test#SetFilename('../phpcs-test-files/project-with-phpcs/foo/test.php')
+
+  let g:executable = ale#path#Simplify(g:dir . '/../phpcs-test-files/project-with-phpcs/vendor/bin/phpcs')
+
+  AssertLinter g:executable,
+  \ ale#Escape(g:executable) . ' -s --report=emacs --stdin-path=%s'
+
+Execute(use_global should override local executable detection):
+  let g:ale_php_phpcs_use_global = 1
+
+  call ale#test#SetFilename('../phpcs-test-files/project-with-phpcs/foo/test.php')
+
+  AssertLinter 'phpcs',
+  \ ale#Escape('phpcs') . ' -s --report=emacs --stdin-path=%s'
+
+Execute(Projects without local executables should use the global one):
+  call ale#test#SetFilename('../phpcs-test-files/project-without-phpcs/foo/test.php')
+
+  AssertLinter 'phpcs',
+  \ ale#Escape('phpcs') . ' -s --report=emacs --stdin-path=%s'