Add a test for edits to the end of the file

Towards #317

Demonstrates the problem reported. When an edit sets the end position
to be the line following the last line of the file the cursor cannot be
placed in at that position so the edit will be done incorrectly, in this
scenario the edit should be done to the end of the last line.

test/integration/test/edit_test.dart

@@ -0,0 +1,99 @@
+import 'dart:async';
+import 'dart:io';
+
+import 'package:_test/vim_remote.dart';
+import 'package:test/test.dart';
+import 'package:json_rpc_2/json_rpc_2.dart';
+import 'package:lsp/lsp.dart'
+    show lspChannel, WorkspaceEdit, TextEdit, Range, Position;
+
+void main() {
+  Stream<Peer> clients;
+  ServerSocket serverSocket;
+  Vim vim;
+  Peer client;
+
+  setUpAll(() async {
+    serverSocket = await ServerSocket.bind('localhost', 0);
+
+    clients = serverSocket.map((socket) {
+      return Peer(lspChannel(socket, socket), onUnhandledError: (error, stack) {
+        fail('Unhandled server error: $error');
+      });
+    }).asBroadcastStream();
+    vim = await Vim.start();
+    await vim.expr('RegisterLanguageServer("text", {'
+        '"command":"localhost:${serverSocket.port}",'
+        '"enabled":v:false,'
+        '})');
+  });
+
+  setUp(() async {
+    final nextClient = clients.first;
+    await vim.edit('foo.txt');
+    await vim.sendKeys(':LSClientEnable<cr>');
+    client = await nextClient;
+  });
+
+  tearDown(() async {
+    await vim.sendKeys(':LSClientDisable<cr>');
+    await vim.sendKeys(':%bwipeout!<cr>');
+    final file = File('foo.txt');
+    if (await file.exists()) await file.delete();
+    await client.done;
+    client = null;
+  });
+
+  tearDownAll(() async {
+    await vim.quit();
+    final log = File(vim.name);
+    print(await log.readAsString());
+    await log.delete();
+    await serverSocket.close();
+  });
+
+  test('edit of entire file', () async {
+    final renameDone = Completer<void>();
+    client
+      ..registerLifecycleMethods({})
+      ..registerMethod('textDocument/rename', (Parameters params) {
+        renameDone.complete();
+        final uri = params['textDocument']['uri'].asString;
+        return WorkspaceEdit((b) => b
+          ..changes = {
+            uri: [
+              TextEdit((b) => b
+                ..newText = 'bar\nbar\n'
+                ..range = Range((b) => b
+                  ..start = Position((b) => b
+                    ..line = 0
+                    ..character = 0)
+                  ..end = Position((b) => b
+                    ..line = 2
+                    ..character = 0)))
+            ]
+          });
+      })
+      ..listen();
+    await vim.sendKeys('ifoo<cr>foo<esc>');
+    await vim.sendKeys(':LSClientRename \'bar\'<cr>');
+    await renameDone;
+    await Future.delayed(const Duration(milliseconds: 100));
+    expect(await vim.expr(r'getline(1, "$")'), 'bar\nbar');
+  }, skip: 'https://github.com/natebosch/vim-lsc/issues/317');
+}
+
+extension LSP on Peer {
+  void registerLifecycleMethods(Map<String, dynamic> capabilities) {
+    registerMethod('initialize', (_) {
+      return {'capabilities': capabilities};
+    });
+    registerMethod('initialized', (_) {});
+    registerMethod('textDocument/didOpen', (_) {});
+    registerMethod('textDocument/didChange', (_) {});
+    registerMethod('shutdown', (_) {});
+    registerMethod('exit', (_) {
+      close();
+    });
+  }
+}