Close #1521 - Allow the language to be set with simple strings for LSP linters

test/command_callback/test_php_langserver_callbacks.vader

@@ -42,9 +42,6 @@ Execute(Vendor executables should be detected):
   \ )),
   \ ale_linters#php#langserver#GetCommand(bufnr(''))
 
-Execute(The language string should be correct):
-  AssertEqual 'php', ale_linters#php#langserver#GetLanguage(bufnr(''))
-
 Execute(The project path should be correct for .git directories):
   call ale#test#SetFilename('php-langserver-project/test.php')
   call mkdir(g:dir . '/.git')

test/command_callback/test_rust_rls_callbacks.vader

@@ -35,9 +35,6 @@ Execute(The toolchain should be ommitted if not given):
   \ ale#Escape('rls'),
   \ ale_linters#rust#rls#GetCommand(bufnr(''))
 
-Execute(The language string should be correct):
-  AssertEqual 'rust', ale_linters#rust#rls#GetLanguage(bufnr(''))
-
 Execute(The project root should be detected correctly):
   AssertEqual '', ale_linters#rust#rls#GetProjectRoot(bufnr(''))
 

test/test_linter_defintion_processing.vader

@@ -421,6 +421,30 @@ Execute(PreProcess should accept LSP server configurations):
 
   AssertEqual 'socket', ale#linter#PreProcess(g:linter).lsp
 
+Execute(PreProcess should accept let you specify the language as just a string):
+  let g:linter = {
+  \ 'name': 'x',
+  \ 'lsp': 'socket',
+  \ 'address_callback': 'X',
+  \ 'language': 'foobar',
+  \ 'project_root_callback': 'x',
+  \}
+
+  AssertEqual 'foobar', ale#linter#PreProcess(g:linter).language_callback(0)
+
+Execute(PreProcess should complain about using language and language_callback together):
+  let g:linter = {
+  \ 'name': 'x',
+  \ 'lsp': 'socket',
+  \ 'address_callback': 'X',
+  \ 'language': 'x',
+  \ 'language_callback': 'x',
+  \ 'project_root_callback': 'x',
+  \}
+
+  AssertThrows call ale#linter#PreProcess(g:linter)
+  AssertEqual 'Only one of `language` or `language_callback` should be set', g:vader_exception
+
 Execute(PreProcess should require an address_callback for LSP socket configurations):
   let g:linter = {
   \ 'name': 'x',