Add fixer for Go modules (#1873)

* Add fixer for Go modules

test/command_callback/test_gobuild_command_callback.vader

@@ -1,9 +1,12 @@
 Before:
+  Save g:ale_go_go_executable
+
   call ale#assert#SetUpLinterTest('go', 'gobuild')
 
   WithChainResults ['/foo/bar', '/foo/baz']
 
 After:
+  Restore
   call ale#assert#TearDownLinterTest()
 
 Execute(The default commands should be correct):
@@ -17,3 +20,12 @@ Execute(Extra options should be supported):
   AssertLinter 'go',
   \ 'cd ' . ale#Escape(expand('%:p:h')) . ' && '
   \   . 'go test --foo-bar -c -o /dev/null ./'
+
+  let g:ale_go_gobuild_options = ''
+
+Execute(The executable should be configurable):
+  let g:ale_go_go_executable = 'foobar'
+
+  AssertLinter 'foobar',
+  \ 'cd ' . ale#Escape(expand('%:p:h')) . ' && '
+  \   . 'foobar test -c -o /dev/null ./'

test/command_callback/test_govet_command_callback.vader

@@ -1,12 +1,19 @@
 Before:
+  Save g:ale_go_go_executable
+  Save g:ale_go_govet_options
   call ale#assert#SetUpLinterTest('go', 'govet')
 
 After:
+  Restore
   call ale#assert#TearDownLinterTest()
 
 Execute(The default command should be correct):
-  AssertLinter 'go', 'cd ' . ale#Escape(expand('%:p:h')) . ' &&  go vet .'
+  AssertLinter 'go', 'cd ' . ale#Escape(expand('%:p:h')) . ' &&  go vet  .'
 
 Execute(Extra options should be supported):
   let g:ale_go_govet_options = '--foo-bar'
-  AssertLinter 'go', 'cd ' . ale#Escape(expand('%:p:h')) . ' &&  go vet . --foo-bar'
+  AssertLinter 'go', 'cd ' . ale#Escape(expand('%:p:h')) . ' &&  go vet  --foo-bar .'
+
+Execute(The executable should be configurable):
+  let g:ale_go_go_executable = 'foobar'
+  AssertLinter 'foobar', 'cd ' . ale#Escape(expand('%:p:h')) . ' &&  foobar vet  .'

test/fixers/test_gomod_fixer_callback.vader

@@ -0,0 +1,24 @@
+Before:
+  Save g:ale_go_go_executable
+
+  " Use an invalid global executable, so we don't match it.
+  let g:ale_go_go_executable = 'xxxinvalid'
+  call ale#test#SetDirectory('/testplugin/test/fixers')
+
+After:
+  Restore
+
+  call ale#test#RestoreDirectory()
+
+Execute(The gomod callback should return the correct default values):
+  call ale#test#SetFilename('../go_files/go.mod')
+  setl ft=gomod
+
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command': ale#Escape('xxxinvalid')
+  \     . ' mod edit -fmt'
+  \     . ' %t',
+  \ },
+  \ ale#fixers#gomod#Fix(bufnr(''))

test/go_files/go.mod

@@ -0,0 +1 @@
+