Before:
  Save g:ale_enabled
  Save b:ale_enabled
  Save g:ale_lint_on_text_changed
  Save g:ale_completion_enabled
  Save g:ale_completion_autoimport
  Save g:ale_completion_max_suggestions
  Save g:ale_linters
  Save b:ale_linters

  let g:ale_enabled = 0
  let b:ale_enabled = 0
  let g:ale_lint_on_text_changed = 'always'
  let g:ale_completion_enabled = 0
  let g:ale_completion_autoimport = 0
  let g:ale_completion_max_suggestions = 50
  let g:ale_linters = {'typescript': ['tsserver'], 'python': ['pyre']}
  unlet! b:ale_linters

  let g:server_started_value = 1
  let g:request_id = 0
  let g:LastCallback = v:null
  let g:LastHandleCallback = v:null
  let g:sent_message_list = []
  let g:code_action_list = []
  let g:execute_list = []
  let g:ale_queue_call_list = []

  runtime autoload/ale.vim
  runtime autoload/ale/util.vim
  runtime autoload/ale/code_action.vim
  runtime autoload/ale/lsp.vim
  runtime autoload/ale/lsp_linter.vim

  function! ale#util#Execute(expr) abort
    call add(g:execute_list, a:expr)
  endfunction

  function! ale#Queue(...) abort
    call add(g:ale_queue_call_list, a:000)
  endfunction

  function! ale#lsp#RegisterCallback(id, Callback) abort
    let g:LastHandleCallback = a:Callback
  endfunction

  function! ale#lsp#NotifyForChanges(id, buffer) abort
  endfunction

  function! ale#lsp#HasCapability(id, capability) abort
    return 1
  endfunction

  function! ale#lsp#Send(id, message) abort
    let g:request_id += 1

    call add(g:sent_message_list, a:message)

    return g:request_id
  endfunction

  function! ale#lsp_linter#StartLSP(buffer, linter, Callback) abort
    let g:LastCallback = a:Callback

    return g:server_started_value
  endfunction

  function! ale#code_action#HandleCodeAction(code_action, options) abort
    Assert !get(a:options, 'should_save')

    call add(g:code_action_list, a:code_action)
  endfunction

  function GetLastMessage()
    return get(g:execute_list, -1, '')
  endfunction

  function CheckLintStates(conn_id, message)
    " Check that we request more linter results after adding completions.
    AssertEqual [[0, '']], g:ale_queue_call_list

    let g:ale_enabled = 0

    let g:ale_queue_call_list = []
    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [], g:ale_queue_call_list

    let g:ale_enabled = 1
    let g:ale_lint_on_text_changed = 1

    let g:ale_queue_call_list = []
    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [[0, '']], g:ale_queue_call_list

    let g:ale_lint_on_text_changed = 'normal'

    let g:ale_queue_call_list = []
    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [[0, '']], g:ale_queue_call_list

    let g:ale_lint_on_text_changed = 'insert'

    let g:ale_queue_call_list = []
    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [[0, '']], g:ale_queue_call_list

    let g:ale_queue_call_list = []
    let g:ale_lint_on_text_changed = 'never'

    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [], g:ale_queue_call_list

    let g:ale_lint_on_text_changed = '0'

    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [], g:ale_queue_call_list

    let g:ale_lint_on_text_changed = 0

    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [], g:ale_queue_call_list

    let g:ale_lint_on_text_changed = 'xxx'

    call g:LastHandleCallback(a:conn_id, a:message)
    AssertEqual [], g:ale_queue_call_list
  endfunction

After:
  call ale#linter#Reset()

  Restore

  delfunction GetLastMessage
  delfunction CheckLintStates

  unlet! g:LastCallback
  unlet! g:LastHandleCallback
  unlet! g:request_id
  unlet! g:server_started_value
  unlet! g:sent_message_list
  unlet! g:code_action_list
  unlet! g:ale_queue_call_list
  unlet! g:execute_list
  unlet! g:received_message
  unlet! b:ale_old_omnifunc
  unlet! b:ale_old_completeopt
  unlet! b:ale_completion_info
  unlet! b:ale_completion_result
  unlet! b:ale_complete_done_time

  runtime autoload/ale.vim
  runtime autoload/ale/util.vim
  runtime autoload/ale/code_action.vim
  runtime autoload/ale/lsp.vim
  runtime autoload/ale/lsp_linter.vim

Given typescript(Some example TypeScript code):
  let xyz = 123
  let foo = missingword

  let abc = 456

Execute(ALEImport should complain when there's no word at the cursor):
  call setpos('.', [bufnr(''), 3, 1, 0])
  ALEImport

  AssertEqual 'echom ''Nothing to complete at cursor!''', GetLastMessage()

Execute(ALEImport should tell the user if no LSP is available):
  let g:server_started_value = 0

  call setpos('.', [bufnr(''), 2, 16, 0])
  ALEImport

  AssertEqual
  \ 'echom ''No completion providers are available.''',
  \ GetLastMessage()

Execute(ALEImport should request imports correctly for tsserver):
  call setpos('.', [bufnr(''), 2, 16, 0])

  ALEImport

  AssertEqual
  \ {
  \   'conn_id': 0,
  \   'request_id': 0,
  \   'source': 'ale-import',
  \   'column': 21,
  \   'line': 2,
  \   'line_length': 21,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastCallback isnot v:null

  call g:LastCallback(ale#linter#Get(&filetype)[0], {
  \ 'connection_id': 347,
  \ 'buffer': bufnr(''),
  \})

  AssertEqual
  \ {
  \   'conn_id': 347,
  \   'request_id': 1,
  \   'source': 'ale-import',
  \   'column': 21,
  \   'line': 2,
  \   'line_length': 21,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastHandleCallback isnot v:null

  call g:LastHandleCallback(347, {
  \ 'request_seq': 1,
  \ 'command': 'completions',
  \ 'body': [
  \   {'name': 'missingwordIgnoreMe'},
  \   {'name': 'missingword'},
  \ ],
  \})

  AssertEqual
  \ [
  \   [0, 'ts@completions', {
  \     'file': expand('%:p'),
  \     'includeExternalModuleExports': 1,
  \     'offset': 21,
  \     'line': 2,
  \     'prefix': 'missingword',
  \   }],
  \   [0, 'ts@completionEntryDetails', {
  \     'file': expand('%:p'),
  \     'entryNames': [{'name': 'missingword'}],
  \     'offset': 21,
  \     'line': 2,
  \   }]
  \ ],
  \ g:sent_message_list
  AssertEqual 2, b:ale_completion_info.request_id

  let g:ale_enabled = 1
  let g:received_message = {
  \ 'request_seq': 2,
  \ 'command': 'completionEntryDetails',
  \ 'body': [
  \   {
  \     'name': 'missingword',
  \     'kind': 'className',
  \     'displayParts': [],
  \     'codeActions': [{
  \        'description': 'import { missingword } from "./Something";',
  \        'changes': [],
  \     }],
  \   },
  \ ],
  \}
  call g:LastHandleCallback(347, g:received_message)

  AssertEqual
  \ [
  \   {
  \     'description': 'import { missingword } from "./Something";',
  \     'changes': [],
  \   },
  \ ],
  \ g:code_action_list

  call CheckLintStates(347, g:received_message)

Execute(ALEImport should tell the user when no completions were found from tsserver):
  call setpos('.', [bufnr(''), 2, 16, 0])

  ALEImport

  AssertEqual
  \ {
  \   'conn_id': 0,
  \   'request_id': 0,
  \   'source': 'ale-import',
  \   'column': 21,
  \   'line': 2,
  \   'line_length': 21,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastCallback isnot v:null

  call g:LastCallback(ale#linter#Get(&filetype)[0], {
  \ 'connection_id': 347,
  \ 'buffer': bufnr(''),
  \})

  AssertEqual
  \ {
  \   'conn_id': 347,
  \   'request_id': 1,
  \   'source': 'ale-import',
  \   'column': 21,
  \   'line': 2,
  \   'line_length': 21,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastHandleCallback isnot v:null

  call g:LastHandleCallback(347, {
  \ 'request_seq': 1,
  \ 'command': 'completions',
  \ 'body': [
  \   {'name': 'missingwordIgnoreMe'},
  \ ],
  \})

  AssertEqual 'echom ''No possible imports found.''', GetLastMessage()

Given python(Some example Python code):
  xyz = 123
  foo = missingword

  abc = 456

Execute(ALEImport should request imports correctly for language servers):
  call setpos('.', [bufnr(''), 2, 12, 0])

  ALEImport

  AssertEqual
  \ {
  \   'conn_id': 0,
  \   'request_id': 0,
  \   'source': 'ale-import',
  \   'column': 17,
  \   'line': 2,
  \   'line_length': 17,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastCallback isnot v:null

  call g:LastCallback(ale#linter#Get(&filetype)[0], {
  \ 'connection_id': 347,
  \ 'buffer': bufnr(''),
  \})

  AssertEqual
  \ {
  \   'conn_id': 347,
  \   'request_id': 1,
  \   'source': 'ale-import',
  \   'column': 17,
  \   'line': 2,
  \   'line_length': 17,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \   'completion_filter': 'ale#completion#python#CompletionItemFilter',
  \ },
  \ b:ale_completion_info
  Assert g:LastHandleCallback isnot v:null

  AssertEqual
  \ [
  \   [0, 'textDocument/completion', {
  \     'textDocument': {'uri': ale#path#ToFileURI(expand('%:p'))},
  \     'position': {'character': 16, 'line': 1}
  \   }],
  \ ],
  \ g:sent_message_list
  AssertEqual 1, b:ale_completion_info.request_id

  let g:ale_enabled = 1
  let g:received_message = {
  \ 'id': 1,
  \ 'jsonrpc': '2.0',
  \ 'result': {
  \   'isIncomplete': v:false,
  \   'items': [
  \     {
  \       'detail': 'Some other word we should ignore',
  \       'filterText': 'missingwordIgnoreMe',
  \       'insertText': 'missingwordIgnoreMe',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingwordIgnoreMe',
  \       'sortText': '3ee19999missingword',
  \       'additionalTextEdits': [
  \         {
  \           'range': {
  \             'start': {'line': 1, 'character': 1},
  \             'end': {'line': 2, 'character': 1},
  \           },
  \           'newText': 'from something import missingwordIgnoreMe',
  \         },
  \       ],
  \     },
  \     {
  \       'detail': 'Some word without text edits',
  \       'filterText': 'missingword',
  \       'insertText': 'missingword',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingword',
  \       'sortText': '3ee19999missingword',
  \     },
  \     {
  \       'detail': 'The word we should use',
  \       'filterText': 'missingword',
  \       'insertText': 'missingword',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingword',
  \       'sortText': '3ee19999missingword',
  \       'additionalTextEdits': [
  \         {
  \           'range': {
  \             'start': {'line': 1, 'character': 1},
  \             'end': {'line': 2, 'character': 1},
  \           },
  \           'newText': 'from something import missingword',
  \         },
  \       ],
  \     },
  \     {
  \       'detail': 'The other word we should not use',
  \       'filterText': 'missingword',
  \       'insertText': 'missingword',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingword',
  \       'sortText': '3ee19999missingword',
  \       'additionalTextEdits': [
  \         {
  \           'range': {
  \             'start': {'line': 1, 'character': 1},
  \             'end': {'line': 2, 'character': 1},
  \           },
  \           'newText': 'from something_else import missingword',
  \         },
  \       ],
  \     },
  \   ],
  \ },
  \}
  call g:LastHandleCallback(347, g:received_message)

  AssertEqual
  \ [
  \   {
  \     'description': 'completion',
  \     'changes': [
  \       {
  \         'fileName': expand('%:p'),
  \         'textChanges': [
  \           {
  \             'start': {'line': 2, 'offset': 2},
  \             'end': {'line': 3, 'offset': 2},
  \             'newText': 'from something import missingword',
  \           },
  \         ],
  \       },
  \     ],
  \   },
  \ ],
  \ g:code_action_list

  call CheckLintStates(347, g:received_message)

Execute(ALEImport should tell the user when no completions were found from a language server):
  call setpos('.', [bufnr(''), 2, 12, 0])

  ALEImport

  AssertEqual
  \ {
  \   'conn_id': 0,
  \   'request_id': 0,
  \   'source': 'ale-import',
  \   'column': 17,
  \   'line': 2,
  \   'line_length': 17,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \ },
  \ b:ale_completion_info
  Assert g:LastCallback isnot v:null

  call g:LastCallback(ale#linter#Get(&filetype)[0], {
  \ 'connection_id': 347,
  \ 'buffer': bufnr(''),
  \})

  AssertEqual
  \ {
  \   'conn_id': 347,
  \   'request_id': 1,
  \   'source': 'ale-import',
  \   'column': 17,
  \   'line': 2,
  \   'line_length': 17,
  \   'prefix': 'missingword',
  \   'additional_edits_only': 1,
  \   'completion_filter': 'ale#completion#python#CompletionItemFilter',
  \ },
  \ b:ale_completion_info
  Assert g:LastHandleCallback isnot v:null

  AssertEqual
  \ [
  \   [0, 'textDocument/completion', {
  \     'textDocument': {'uri': ale#path#ToFileURI(expand('%:p'))},
  \     'position': {'character': 16, 'line': 1}
  \   }],
  \ ],
  \ g:sent_message_list
  AssertEqual 1, b:ale_completion_info.request_id

  let g:received_message = {
  \ 'id': 1,
  \ 'jsonrpc': '2.0',
  \ 'result': {
  \   'isIncomplete': v:false,
  \   'items': [
  \     {
  \       'detail': 'Some other word we should ignore',
  \       'filterText': 'missingwordIgnoreMe',
  \       'insertText': 'missingwordIgnoreMe',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingwordIgnoreMe',
  \       'sortText': '3ee19999missingword',
  \       'additionalTextEdits': [
  \         {
  \           'range': {
  \             'start': {'line': 1, 'character': 1},
  \             'end': {'line': 2, 'character': 1},
  \           },
  \           'newText': 'from something import missingwordIgnoreMe',
  \         },
  \       ],
  \     },
  \     {
  \       'detail': 'Some word without text edits',
  \       'filterText': 'missingword',
  \       'insertText': 'missingword',
  \       'insertTextFormat': 1,
  \       'kind': 6,
  \       'label': ' missingword',
  \       'sortText': '3ee19999missingword',
  \     },
  \   ],
  \ },
  \}
  call g:LastHandleCallback(347, g:received_message)

  AssertEqual 'echom ''No possible imports found.''', GetLastMessage()