#2132 Use an on-init callback for all LSP logic

14 files changed, 181 insertions, 192 deletions

diff --git a/autoload/ale/completion.vim b/autoload/ale/completion.vim
index 8a96032e..4a566d4f 100644
--- a/autoload/ale/completion.vim
+++ b/autoload/ale/completion.vim
@@ -446,10 +446,15 @@ function! ale#completion#HandleLSPResponse(conn_id, response) abort
     \)
 endfunction
 
-function! s:OnReady(linter, lsp_details, ...) abort
-    let l:buffer = a:lsp_details.buffer
+function! s:OnReady(linter, lsp_details) abort
     let l:id = a:lsp_details.connection_id
 
+    if !ale#lsp#HasCapability(l:id, 'completion')
+        return
+    endif
+
+    let l:buffer = a:lsp_details.buffer
+
     " If we have sent a completion request already, don't send another.
     if b:ale_completion_info.request_id
         return
@@ -498,21 +503,6 @@ function! s:OnReady(linter, lsp_details, ...) abort
     endif
 endfunction
 
-function! s:GetLSPCompletions(linter) abort
-    let l:buffer = bufnr('')
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
-
-    if empty(l:lsp_details)
-        return 0
-    endif
-
-    let l:id = l:lsp_details.connection_id
-
-    let l:OnReady = function('s:OnReady', [a:linter, l:lsp_details])
-
-    call ale#lsp#WaitForCapability(l:id, 'completion', l:OnReady)
-endfunction
-
 function! ale#completion#GetCompletions() abort
     if !g:ale_completion_enabled
         return
@@ -543,9 +533,12 @@ function! ale#completion#AlwaysGetCompletions(need_prefix) abort
     \   'request_id': 0,
     \}
 
+    let l:buffer = bufnr('')
+    let l:Callback = function('s:OnReady')
+
     for l:linter in ale#linter#Get(&filetype)
         if !empty(l:linter.lsp)
-            call s:GetLSPCompletions(l:linter)
+            call ale#lsp_linter#StartLSP(l:buffer, l:linter, l:Callback)
         endif
     endfor
 endfunction
diff --git a/autoload/ale/definition.vim b/autoload/ale/definition.vim
index a732e501..9fc47834 100644
--- a/autoload/ale/definition.vim
+++ b/autoload/ale/definition.vim
@@ -57,10 +57,15 @@ function! ale#definition#HandleLSPResponse(conn_id, response) abort
     endif
 endfunction
 
-function! s:OnReady(linter, lsp_details, line, column, options, capability, ...) abort
-    let l:buffer = a:lsp_details.buffer
+function! s:OnReady(line, column, options, capability, linter, lsp_details) abort
     let l:id = a:lsp_details.connection_id
 
+    if !ale#lsp#HasCapability(l:id, a:capability)
+        return
+    endif
+
+    let l:buffer = a:lsp_details.buffer
+
     let l:Callback = a:linter.lsp is# 'tsserver'
     \   ? function('ale#definition#HandleTSServerResponse')
     \   : function('ale#definition#HandleLSPResponse')
@@ -100,21 +105,13 @@ endfunction
 function! s:GoToLSPDefinition(linter, options, capability) abort
     let l:buffer = bufnr('')
     let [l:line, l:column] = getcurpos()[1:2]
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
-
-    if a:linter.lsp isnot# 'tsserver'
-        let l:column = min([l:column, len(getline(l:line))])
-    endif
-
-    if empty(l:lsp_details)
-        return 0
-    endif
-
-    let l:id = l:lsp_details.connection_id
+    let l:column = min([l:column, len(getline(l:line))])
 
-    call ale#lsp#WaitForCapability(l:id, a:capability, function('s:OnReady', [
-    \   a:linter, l:lsp_details, l:line, l:column, a:options, a:capability
-    \]))
+    let l:Callback = function(
+    \   's:OnReady',
+    \   [l:line, l:column, a:options, a:capability]
+    \)
+    call ale#lsp_linter#StartLSP(l:buffer, a:linter, l:Callback)
 endfunction
 
 function! ale#definition#GoTo(options) abort
diff --git a/autoload/ale/hover.vim b/autoload/ale/hover.vim
index 873c9558..6a3f58c9 100644
--- a/autoload/ale/hover.vim
+++ b/autoload/ale/hover.vim
@@ -106,10 +106,15 @@ function! ale#hover#HandleLSPResponse(conn_id, response) abort
     endif
 endfunction
 
-function! s:OnReady(linter, lsp_details, line, column, opt, ...) abort
-    let l:buffer = a:lsp_details.buffer
+function! s:OnReady(line, column, opt, linter, lsp_details) abort
     let l:id = a:lsp_details.connection_id
 
+    if !ale#lsp#HasCapability(l:id, 'hover')
+        return
+    endif
+
+    let l:buffer = a:lsp_details.buffer
+
     let l:Callback = a:linter.lsp is# 'tsserver'
     \   ? function('ale#hover#HandleTSServerResponse')
     \   : function('ale#hover#HandleLSPResponse')
@@ -144,20 +149,6 @@ function! s:OnReady(linter, lsp_details, line, column, opt, ...) abort
     \}
 endfunction
 
-function! s:ShowDetails(linter, buffer, line, column, opt, ...) abort
-    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter)
-
-    if empty(l:lsp_details)
-        return 0
-    endif
-
-    let l:id = l:lsp_details.connection_id
-
-    call ale#lsp#WaitForCapability(l:id, 'hover', function('s:OnReady', [
-    \   a:linter, l:lsp_details, a:line, a:column, a:opt
-    \]))
-endfunction
-
 " Obtain Hover information for the specified position
 " Pass optional arguments in the dictionary opt.
 " Currently, only one key/value is useful:
@@ -169,12 +160,13 @@ endfunction
 " - as status message otherwise
 function! ale#hover#Show(buffer, line, col, opt) abort
     let l:show_documentation = get(a:opt, 'show_documentation', 0)
+    let l:Callback = function('s:OnReady', [a:line, a:col, a:opt])
 
     for l:linter in ale#linter#Get(getbufvar(a:buffer, '&filetype'))
         " Only tsserver supports documentation requests at the moment.
         if !empty(l:linter.lsp)
         \&& (!l:show_documentation || l:linter.lsp is# 'tsserver')
-            call s:ShowDetails(l:linter, a:buffer, a:line, a:col, a:opt)
+            call ale#lsp_linter#StartLSP(a:buffer, l:linter, l:Callback)
         endif
     endfor
 endfunction
diff --git a/autoload/ale/lsp.vim b/autoload/ale/lsp.vim
index 5667b2e0..d1b3710e 100644
--- a/autoload/ale/lsp.vim
+++ b/autoload/ale/lsp.vim
@@ -36,7 +36,7 @@ function! ale#lsp#Register(executable_or_address, project, init_options) abort
         \   'config': {},
         \   'callback_list': [],
         \   'message_queue': [],
-        \   'capabilities_queue': [],
+        \   'init_queue': [],
         \   'capabilities': {
         \       'hover': 0,
         \       'references': 0,
@@ -259,13 +259,11 @@ function! ale#lsp#HandleInitResponse(conn, response) abort
     let a:conn.message_queue = []
 
     " Call capabilities callbacks queued for the project.
-    for [l:capability, l:Callback] in a:conn.capabilities_queue
-        if a:conn.capabilities[l:capability]
-            call call(l:Callback, [a:conn.id])
-        endif
+    for [l:Callback] in a:conn.init_queue
+        call l:Callback()
     endfor
 
-    let a:conn.capabilities_queue = []
+    let a:conn.init_queue = []
 endfunction
 
 function! ale#lsp#HandleMessage(conn_id, message) abort
@@ -501,26 +499,32 @@ function! ale#lsp#NotifyForChanges(conn_id, buffer) abort
     return l:notified
 endfunction
 
-" Given some LSP details that must contain at least `connection_id` and
-" `project_root` keys,
-function! ale#lsp#WaitForCapability(conn_id, capability, callback) abort
+" Wait for an LSP server to be initialized.
+function! ale#lsp#OnInit(conn_id, Callback) abort
     let l:conn = get(s:connections, a:conn_id, {})
 
     if empty(l:conn)
         return
     endif
 
+    if l:conn.initialized
+        call a:Callback()
+    else
+        call add(l:conn.init_queue, a:Callback)
+    endif
+endfunction
+
+" Check if an LSP has a given capability.
+function! ale#lsp#HasCapability(conn_id, capability) abort
+    let l:conn = get(s:connections, a:conn_id, {})
+
+    if empty(l:conn)
+        return 0
+    endif
+
     if type(get(l:conn.capabilities, a:capability, v:null)) isnot v:t_number
         throw 'Invalid capability ' . a:capability
     endif
 
-    if l:conn.initialized
-        if l:conn.capabilities[a:capability]
-            " The project has been initialized, so call the callback now.
-            call call(a:callback, [a:conn_id])
-        endif
-    else
-        " Call the callback later, once we have the information we need.
-        call add(l:conn.capabilities_queue, [a:capability, a:callback])
-    endif
+    return l:conn.capabilities[a:capability]
 endfunction
diff --git a/autoload/ale/lsp_linter.vim b/autoload/ale/lsp_linter.vim
index 70299655..95b92228 100644
--- a/autoload/ale/lsp_linter.vim
+++ b/autoload/ale/lsp_linter.vim
@@ -187,7 +187,7 @@ endfunction
 
 " Given a buffer, an LSP linter, start up an LSP linter and get ready to
 " receive messages for the document.
-function! ale#lsp_linter#StartLSP(buffer, linter) abort
+function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let l:command = ''
     let l:address = ''
     let l:root = ale#lsp_linter#FindProjectRoot(a:buffer, a:linter)
@@ -195,7 +195,7 @@ function! ale#lsp_linter#StartLSP(buffer, linter) abort
     if empty(l:root) && a:linter.lsp isnot# 'tsserver'
         " If there's no project root, then we can't check files with LSP,
         " unless we are using tsserver, which doesn't use project roots.
-        return {}
+        return 0
     endif
 
     let l:init_options = ale#lsp_linter#GetOptions(a:buffer, a:linter)
@@ -208,7 +208,7 @@ function! ale#lsp_linter#StartLSP(buffer, linter) abort
         let l:executable = ale#linter#GetExecutable(a:buffer, a:linter)
 
         if empty(l:executable) || !executable(l:executable)
-            return {}
+            return 0
         endif
 
         let l:conn_id = ale#lsp#Register(l:executable, l:root, l:init_options)
@@ -225,7 +225,7 @@ function! ale#lsp_linter#StartLSP(buffer, linter) abort
             call ale#history#Add(a:buffer, 'failed', l:conn_id, l:command)
         endif
 
-        return {}
+        return 0
     endif
 
     " tsserver behaves differently, so tell the LSP API that it is tsserver.
@@ -257,18 +257,20 @@ function! ale#lsp_linter#StartLSP(buffer, linter) abort
         call ale#lsp#NotifyForChanges(l:conn_id, a:buffer)
     endif
 
-    return l:details
+    call ale#lsp#OnInit(l:conn_id, {-> a:Callback(a:linter, l:details)})
+
+    return 1
 endfunction
 
-function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
-    let l:info = g:ale_buffer_info[a:buffer]
-    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter)
+function! s:CheckWithLSP(linter, details) abort
+    let l:buffer = a:details.buffer
+    let l:info = get(g:ale_buffer_info, l:buffer)
 
-    if empty(l:lsp_details)
-        return 0
+    if empty(l:info)
+        return
     endif
 
-    let l:id = l:lsp_details.connection_id
+    let l:id = a:details.connection_id
 
     " Register a callback now for handling errors now.
     let l:Callback = function('ale#lsp_linter#HandleLSPResponse')
@@ -278,16 +280,16 @@ function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
     let s:lsp_linter_map[l:id] = a:linter.name
 
     if a:linter.lsp is# 'tsserver'
-        let l:message = ale#lsp#tsserver_message#Geterr(a:buffer)
+        let l:message = ale#lsp#tsserver_message#Geterr(l:buffer)
         let l:notified = ale#lsp#Send(l:id, l:message) != 0
     else
-        let l:notified = ale#lsp#NotifyForChanges(l:id, a:buffer)
+        let l:notified = ale#lsp#NotifyForChanges(l:id, l:buffer)
     endif
 
     " If this was a file save event, also notify the server of that.
     if a:linter.lsp isnot# 'tsserver'
-    \&& getbufvar(a:buffer, 'ale_save_event_fired', 0)
-        let l:save_message = ale#lsp#message#DidSave(a:buffer)
+    \&& getbufvar(l:buffer, 'ale_save_event_fired', 0)
+        let l:save_message = ale#lsp#message#DidSave(l:buffer)
         let l:notified = ale#lsp#Send(l:id, l:save_message) != 0
     endif
 
@@ -305,8 +307,10 @@ function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
             call add(l:info.active_linter_list, a:linter)
         endif
     endif
+endfunction
 
-    return l:notified
+function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
+    return ale#lsp_linter#StartLSP(a:buffer, a:linter, function('s:CheckWithLSP'))
 endfunction
 
 " Clear LSP linter data for the linting engine.
diff --git a/autoload/ale/references.vim b/autoload/ale/references.vim
index 6d33b443..14f3cd15 100644
--- a/autoload/ale/references.vim
+++ b/autoload/ale/references.vim
@@ -65,10 +65,15 @@ function! ale#references#HandleLSPResponse(conn_id, response) abort
     endif
 endfunction
 
-function! s:OnReady(linter, lsp_details, line, column, options, ...) abort
-    let l:buffer = a:lsp_details.buffer
+function! s:OnReady(line, column, options, linter, lsp_details) abort
     let l:id = a:lsp_details.connection_id
 
+    if !ale#lsp#HasCapability(l:id, 'references')
+        return
+    endif
+
+    let l:buffer = a:lsp_details.buffer
+
     let l:Callback = a:linter.lsp is# 'tsserver'
     \   ? function('ale#references#HandleTSServerResponse')
     \   : function('ale#references#HandleLSPResponse')
@@ -96,27 +101,6 @@ function! s:OnReady(linter, lsp_details, line, column, options, ...) abort
     \}
 endfunction
 
-function! s:FindReferences(linter, options) abort
-    let l:buffer = bufnr('')
-    let [l:line, l:column] = getcurpos()[1:2]
-
-    if a:linter.lsp isnot# 'tsserver'
-        let l:column = min([l:column, len(getline(l:line))])
-    endif
-
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
-
-    if empty(l:lsp_details)
-        return 0
-    endif
-
-    let l:id = l:lsp_details.connection_id
-
-    call ale#lsp#WaitForCapability(l:id, 'references', function('s:OnReady', [
-    \   a:linter, l:lsp_details, l:line, l:column, a:options
-    \]))
-endfunction
-
 function! ale#references#Find(...) abort
     let l:options = {}
 
@@ -128,9 +112,14 @@ function! ale#references#Find(...) abort
         endfor
     endif
 
+    let l:buffer = bufnr('')
+    let [l:line, l:column] = getcurpos()[1:2]
+    let l:column = min([l:column, len(getline(l:line))])
+    let l:Callback = function('s:OnReady', [l:line, l:column, l:options])
+
     for l:linter in ale#linter#Get(&filetype)
         if !empty(l:linter.lsp)
-            call s:FindReferences(l:linter, l:options)
+            call ale#lsp_linter#StartLSP(l:buffer, l:linter, l:Callback)
         endif
     endfor
 endfunction
diff --git a/autoload/ale/symbol.vim b/autoload/ale/symbol.vim
index dba78afa..ae4151ab 100644
--- a/autoload/ale/symbol.vim
+++ b/autoload/ale/symbol.vim
@@ -57,7 +57,13 @@ function! ale#symbol#HandleLSPResponse(conn_id, response) abort
     endif
 endfunction
 
-function! s:OnReady(linter, lsp_details, query, options, ...) abort
+function! s:OnReady(query, options, linter, lsp_details) abort
+    let l:id = a:lsp_details.connection_id
+
+    if !ale#lsp#HasCapability(l:id, 'symbol_search')
+        return
+    endif
+
     let l:buffer = a:lsp_details.buffer
 
     " If we already made a request, stop here.
@@ -65,8 +71,6 @@ function! s:OnReady(linter, lsp_details, query, options, ...) abort
         return
     endif
 
-    let l:id = a:lsp_details.connection_id
-
     let l:Callback = function('ale#symbol#HandleLSPResponse')
     call ale#lsp#RegisterCallback(l:id, l:Callback)
 
@@ -80,18 +84,6 @@ function! s:OnReady(linter, lsp_details, query, options, ...) abort
     \}
 endfunction
 
-function! s:Search(linter, buffer, query, options) abort
-    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter)
-
-    if !empty(l:lsp_details)
-        call ale#lsp#WaitForCapability(
-        \   l:lsp_details.connection_id,
-        \   'symbol_search',
-        \   function('s:OnReady', [a:linter, l:lsp_details, a:query, a:options]),
-        \)
-    endif
-endfunction
-
 function! ale#symbol#Search(args) abort
     let [l:opts, l:query] = ale#args#Parse(['relative'], a:args)
 
@@ -108,10 +100,11 @@ function! ale#symbol#Search(args) abort
 
     " Set a flag so we only make one request.
     call setbufvar(l:buffer, 'ale_symbol_request_made', 0)
+    let l:Callback = function('s:OnReady', [l:query, l:options])
 
     for l:linter in ale#linter#Get(getbufvar(l:buffer, '&filetype'))
         if !empty(l:linter.lsp) && l:linter.lsp isnot# 'tsserver'
-            call s:Search(l:linter, l:buffer, l:query, l:options)
+            call ale#lsp_linter#StartLSP(l:buffer, l:linter, l:Callback)
         endif
     endfor
 endfunction
diff --git a/test/completion/test_lsp_completion_messages.vader b/test/completion/test_lsp_completion_messages.vader
index 130f31b9..35b167b6 100644
--- a/test/completion/test_lsp_completion_messages.vader
+++ b/test/completion/test_lsp_completion_messages.vader
@@ -16,18 +16,20 @@ Before:
   let g:capability_checked = ''
   let g:conn_id = v:null
   let g:Callback = ''
-  let g:wait_callback_list = []
+  let g:init_callback_list = []
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
 
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'python',
     \}
+
+    call add(g:init_callback_list, {-> a:Callback(a:linter, l:details)})
   endfunction
 
   " Pretend we're in insert mode for most tests.
@@ -35,9 +37,10 @@ Before:
     return 'i'
   endfunction
 
-  function! ale#lsp#WaitForCapability(conn_id, capability, callback) abort
+  function! ale#lsp#HasCapability(conn_id, capability) abort
     let g:capability_checked = a:capability
-    call add(g:wait_callback_list, a:callback)
+
+    return 1
   endfunction
 
   function! ale#lsp#RegisterCallback(conn_id, callback) abort
@@ -60,7 +63,7 @@ After:
 
   unlet! g:message_list
   unlet! g:capability_checked
-  unlet! g:wait_callback_list
+  unlet! g:init_callback_list
   unlet! g:conn_id
   unlet! g:Callback
   unlet! b:ale_old_omnifunc
@@ -104,9 +107,10 @@ Execute(The right message should be sent for the initial tsserver request):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual 1, len(g:wait_callback_list)
+  AssertEqual 1, len(g:init_callback_list)
+  call map(g:init_callback_list, 'v:val()')
+
   AssertEqual 'completion', g:capability_checked
-  call map(g:wait_callback_list, 'v:val([g:conn_id, ''/foo/bar''])')
 
   " We should send the right callback.
   AssertEqual
@@ -191,9 +195,10 @@ Execute(The right message should be sent for the initial LSP request):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual 1, len(g:wait_callback_list)
+  AssertEqual 1, len(g:init_callback_list)
+  call map(g:init_callback_list, 'v:val()')
+
   AssertEqual 'completion', g:capability_checked
-  call map(g:wait_callback_list, 'v:val([g:conn_id, ''/foo/bar''])')
 
   " We should send the right callback.
   AssertEqual
@@ -258,9 +263,10 @@ Execute(Two completion requests shouldn't be sent in a row):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual 2, len(g:wait_callback_list)
+  AssertEqual 2, len(g:init_callback_list)
+  call map(g:init_callback_list, 'v:val()')
+
   AssertEqual 'completion', g:capability_checked
-  call map(g:wait_callback_list, 'v:val([347, ''/foo/bar''])')
 
   " We should only send one completion message for two LSP servers.
   AssertEqual
diff --git a/test/lsp/test_did_save_event.vader b/test/lsp/test_did_save_event.vader
index f8ff8f70..1d6065ec 100644
--- a/test/lsp/test_did_save_event.vader
+++ b/test/lsp/test_did_save_event.vader
@@ -34,16 +34,19 @@ Before:
   \ })
   let g:ale_linters = {'foobar': ['dummy_linter']}
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
-
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'foobar',
     \}
+
+    call a:Callback(a:linter, l:details)
+
+    return 1
   endfunction
 
   " Replace the Send function for LSP, so we can monitor calls to it.
@@ -61,6 +64,7 @@ After:
   unlet! b:ale_enabled
   unlet! b:ale_linters
   unlet! g:message_list
+  unlet! b:ale_save_event_fired
 
   delfunction LanguageCallback
   delfunction ProjectRootCallback
diff --git a/test/lsp/test_lsp_command_formatting.vader b/test/lsp/test_lsp_command_formatting.vader
index fcd4f78c..ec3b4120 100644
--- a/test/lsp/test_lsp_command_formatting.vader
+++ b/test/lsp/test_lsp_command_formatting.vader
@@ -24,6 +24,7 @@ Execute(Command formatting should be applied correctly for LSP linters):
   \   'executable': has('win32') ? 'cmd': 'true',
   \   'command': '%e --foo',
   \ },
+  \ {-> 0}
   \)
 
   if has('win32')
diff --git a/test/lsp/test_other_initialize_message_handling.vader b/test/lsp/test_other_initialize_message_handling.vader
index 2f59535d..8ae63e91 100644
--- a/test/lsp/test_other_initialize_message_handling.vader
+++ b/test/lsp/test_other_initialize_message_handling.vader
@@ -10,7 +10,7 @@ Before:
   \ 'config': {},
   \ 'callback_list': [],
   \ 'message_queue': [],
-  \ 'capabilities_queue': [],
+  \ 'init_queue': [],
   \ 'capabilities': {
   \   'hover': 0,
   \   'references': 0,
diff --git a/test/test_find_references.vader b/test/test_find_references.vader
index d31424ef..078333bb 100644
--- a/test/test_find_references.vader
+++ b/test/test_find_references.vader
@@ -11,28 +11,30 @@ Before:
   let g:options = {}
   let g:capability_checked = ''
   let g:conn_id = v:null
-  let g:WaitCallback = v:null
+  let g:InitCallback = v:null
 
   runtime autoload/ale/linter.vim
   runtime autoload/ale/lsp.vim
   runtime autoload/ale/util.vim
   runtime autoload/ale/preview.vim
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
-
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'python',
     \}
+
+    let g:InitCallback = {-> a:Callback(a:linter, l:details)}
   endfunction
 
-  function! ale#lsp#WaitForCapability(conn_id, capability, callback) abort
+  function! ale#lsp#HasCapability(conn_id, capability) abort
     let g:capability_checked = a:capability
-    let g:WaitCallback = a:callback
+
+    return 1
   endfunction
 
   function! ale#lsp#RegisterCallback(conn_id, callback) abort
@@ -65,7 +67,7 @@ After:
   call ale#linter#Reset()
 
   unlet! g:capability_checked
-  unlet! g:WaitCallback
+  unlet! g:InitCallback
   unlet! g:old_filename
   unlet! g:conn_id
   unlet! g:Callback
@@ -173,10 +175,10 @@ Execute(tsserver reference requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'references', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'references', g:capability_checked
   AssertEqual
   \ 'function(''ale#references#HandleTSServerResponse'')',
   \ string(g:Callback)
@@ -191,7 +193,7 @@ Execute('-relative' argument should enable 'use_relative_paths' in HandleTSServe
 
   ALEFindReferences -relative
 
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  call g:InitCallback()
 
   AssertEqual {'42': {'use_relative_paths': 1}}, ale#references#GetMap()
 
@@ -264,10 +266,10 @@ Execute(LSP reference requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'references', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'references', g:capability_checked
   AssertEqual
   \ 'function(''ale#references#HandleLSPResponse'')',
   \ string(g:Callback)
@@ -298,6 +300,6 @@ Execute('-relative' argument should enable 'use_relative_paths' in HandleLSPResp
 
   ALEFindReferences -relative
 
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  call g:InitCallback()
 
   AssertEqual {'42': {'use_relative_paths': 1}}, ale#references#GetMap()
diff --git a/test/test_go_to_definition.vader b/test/test_go_to_definition.vader
index 3cc2a58c..880d7123 100644
--- a/test/test_go_to_definition.vader
+++ b/test/test_go_to_definition.vader
@@ -8,27 +8,29 @@ Before:
   let g:expr_list = []
   let g:capability_checked = ''
   let g:conn_id = v:null
-  let g:WaitCallback = v:null
+  let g:InitCallback = v:null
 
   runtime autoload/ale/linter.vim
   runtime autoload/ale/lsp.vim
   runtime autoload/ale/util.vim
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
-
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'python',
     \}
+
+    let g:InitCallback = {-> a:Callback(a:linter, l:details)}
   endfunction
 
-  function! ale#lsp#WaitForCapability(conn_id, capability, callback) abort
+  function! ale#lsp#HasCapability(conn_id, capability) abort
     let g:capability_checked = a:capability
-    let g:WaitCallback = a:callback
+
+    return 1
   endfunction
 
   function! ale#lsp#RegisterCallback(conn_id, callback) abort
@@ -55,7 +57,7 @@ After:
   call ale#linter#Reset()
 
   unlet! g:capability_checked
-  unlet! g:WaitCallback
+  unlet! g:InitCallback
   unlet! g:old_filename
   unlet! g:conn_id
   unlet! g:Callback
@@ -205,10 +207,10 @@ Execute(tsserver definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'definition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'definition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleTSServerResponse'')',
   \ string(g:Callback)
@@ -226,10 +228,10 @@ Execute(tsserver tab definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'definition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'definition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleTSServerResponse'')',
   \ string(g:Callback)
@@ -358,10 +360,10 @@ Execute(LSP definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'definition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'definition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleLSPResponse'')',
   \ string(g:Callback)
@@ -394,10 +396,10 @@ Execute(LSP type definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'typeDefinition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'typeDefinition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleLSPResponse'')',
   \ string(g:Callback)
@@ -430,10 +432,10 @@ Execute(LSP tab definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'definition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'definition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleLSPResponse'')',
   \ string(g:Callback)
@@ -466,10 +468,10 @@ Execute(LSP tab type definition requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  AssertEqual 'typeDefinition', g:capability_checked
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'typeDefinition', g:capability_checked
   AssertEqual
   \ 'function(''ale#definition#HandleLSPResponse'')',
   \ string(g:Callback)
diff --git a/test/test_symbol_search.vader b/test/test_symbol_search.vader
index 9d50e267..053a8b04 100644
--- a/test/test_symbol_search.vader
+++ b/test/test_symbol_search.vader
@@ -10,28 +10,30 @@ Before:
   let g:options = {}
   let g:capability_checked = ''
   let g:conn_id = v:null
-  let g:WaitCallback = v:null
+  let g:InitCallback = v:null
 
   runtime autoload/ale/lsp_linter.vim
   runtime autoload/ale/lsp.vim
   runtime autoload/ale/util.vim
   runtime autoload/ale/preview.vim
 
-  function! ale#lsp_linter#StartLSP(buffer, linter) abort
+  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
     let g:conn_id = ale#lsp#Register('executable', '/foo/bar', {})
     call ale#lsp#MarkDocumentAsOpen(g:conn_id, a:buffer)
-
-    return {
+    let l:details = {
     \ 'buffer': a:buffer,
     \ 'connection_id': g:conn_id,
     \ 'project_root': '/foo/bar',
     \ 'language_id': 'python',
     \}
+
+    let g:InitCallback = {-> a:Callback(a:linter, l:details)}
   endfunction
 
-  function! ale#lsp#WaitForCapability(conn_id, capability, callback) abort
+  function! ale#lsp#HasCapability(conn_id, capability) abort
     let g:capability_checked = a:capability
-    let g:WaitCallback = a:callback
+
+    return 1
   endfunction
 
   function! ale#lsp#RegisterCallback(conn_id, callback) abort
@@ -59,7 +61,7 @@ After:
   call ale#linter#Reset()
 
   unlet! g:capability_checked
-  unlet! g:WaitCallback
+  unlet! g:InitCallback
   unlet! g:conn_id
   unlet! g:Callback
   unlet! g:message_list
@@ -159,10 +161,10 @@ Execute(LSP symbol requests should be sent):
   " We shouldn't register the callback yet.
   AssertEqual '''''', string(g:Callback)
 
-  AssertEqual 'symbol_search', g:capability_checked
-  AssertEqual type(function('type')), type(g:WaitCallback)
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  AssertEqual type(function('type')), type(g:InitCallback)
+  call g:InitCallback()
 
+  AssertEqual 'symbol_search', g:capability_checked
   AssertEqual
   \ 'function(''ale#symbol#HandleLSPResponse'')',
   \ string(g:Callback)
@@ -182,6 +184,6 @@ Execute('-relative' argument should enable 'use_relative_paths' in HandleLSPResp
 
   ALESymbolSearch -relative foo bar
 
-  call call(g:WaitCallback, [g:conn_id, '/foo/bar'])
+  call g:InitCallback()
 
   AssertEqual {'42': {'buffer': bufnr(''), 'use_relative_paths': 1}}, ale#symbol#GetMap()