Massively reduce the amount of code needed for linter tests

test/command_callback/test_c_cppcheck_command_callbacks.vader

@@ -1,49 +1,24 @@
 Before:
-  Save g:ale_c_cppcheck_executable
-  Save g:ale_c_cppcheck_options
-
-  unlet! g:ale_c_cppcheck_executable
-  unlet! b:ale_c_cppcheck_executable
-  unlet! g:ale_c_cppcheck_options
-  unlet! b:ale_c_cppcheck_options
-
-  runtime ale_linters/c/cppcheck.vim
+  call ale#assert#SetUpLinterTest('c', 'cppcheck')
 
   let b:command_tail = ' -q --language=c --enable=style %t'
 
-  call ale#test#SetDirectory('/testplugin/test/command_callback')
-
 After:
-  Restore
+  call ale#assert#TearDownLinterTest()
+
   unlet! b:command_tail
-  unlet! b:ale_c_cppcheck_executable
-  unlet! b:ale_c_cppcheck_options
-  call ale#linter#Reset()
-  call ale#test#RestoreDirectory()
 
 Execute(The executable should be configurable):
-  AssertEqual 'cppcheck', ale_linters#c#cppcheck#GetExecutable(bufnr(''))
+  AssertLinter 'cppcheck', ale#Escape('cppcheck') . b:command_tail
 
   let b:ale_c_cppcheck_executable = 'foobar'
 
-  AssertEqual 'foobar', ale_linters#c#cppcheck#GetExecutable(bufnr(''))
-
-Execute(The executable should be used in the command):
-  AssertEqual
-  \ ale#Escape('cppcheck') . b:command_tail,
-  \ ale_linters#c#cppcheck#GetCommand(bufnr(''))
-
-  let b:ale_c_cppcheck_executable = 'foobar'
-
-  AssertEqual
-  \ ale#Escape('foobar') . b:command_tail,
-  \ ale_linters#c#cppcheck#GetCommand(bufnr(''))
+  AssertLinter 'foobar', ale#Escape('foobar') . b:command_tail
 
 Execute(cppcheck for C++ should detect compile_commands.json files):
   call ale#test#SetFilename('cppcheck_paths/one/foo.cpp')
 
-  AssertEqual
+  AssertLinter 'cppcheck',
   \ 'cd ' . ale#Escape(ale#path#Simplify(g:dir . '/cppcheck_paths/one')) . ' && '
   \   . ale#Escape('cppcheck')
-  \   . ' -q --language=c --project=compile_commands.json --enable=style %t',
-  \ ale_linters#c#cppcheck#GetCommand(bufnr(''))
+  \   . ' -q --language=c --project=compile_commands.json --enable=style %t'