Add a code formatting task to CAKE (octokit#1550)

* add FormatCode build task

* add log message to indicate we generate temp .csproj files to run the code formatter

build/Tasks/FormatCode.cs

@@ -0,0 +1,74 @@
+using System;
+using System.IO;
+using System.Linq;
+using Cake.Common;
+using Cake.Common.Diagnostics;
+using Cake.Core;
+using Cake.Core.IO;
+using Cake.Frosting;
+
+public class FormatCode : FrostingTask<BuildContext>
+{
+    public override void Run(BuildContext context)
+    {
+        var codeFormatterExe = context.FileSystem
+            .GetDirectory("tools")
+            .GetFiles("CodeFormatter.exe", SearchScope.Recursive)
+            .First()
+            .Path
+            .MakeAbsolute(context.Environment);
+
+        foreach (var project in context.Projects)
+        {
+            context.Information("Formatting code of {0}", project.Name);
+
+            var tempCsprojFile = CreateTempCsproj(context, project.Name);
+            context.Information("Generated temporary {0} file to run the formatter", new FilePath(tempCsprojFile).GetFilename());
+
+            var exitCode = context.StartProcess(
+                codeFormatterExe,
+                $"{tempCsprojFile} /nocopyright /nounicode");
+
+            if (exitCode != 0)
+            {
+                throw new CakeException($"An error occured while formatting code of {project.Name}");
+            }
+        }
+
+        context.Information("Successfully formatted code of all the projects");
+    }
+
+    public override bool ShouldRun(BuildContext context)
+    {
+        return context.IsRunningOnWindows();
+    }
+
+    private static string CreateTempCsproj(BuildContext context, string projectName)
+    {
+        DirectoryPath tempFolder = System.IO.Path.GetTempPath();
+        var projectCsproj = tempFolder.CombineWithFilePath($"{projectName}.csproj").FullPath;
+
+        var files = context.FileSystem
+            .GetDirectory(projectName)
+            .GetFiles("*.cs", SearchScope.Recursive)
+            .Select(x => x.Path.MakeAbsolute(context.Environment))
+            .ToArray();
+
+        var compileElements = files
+            .Select(x => $"<Compile Include=\"{x}\" />")
+            .ToArray();
+
+        var csprojContent =
+$@"<?xml version=""1.0"" encoding=""utf-8""?>
+<Project ToolsVersion=""4.0"" DefaultTargets=""Build"" xmlns=""http://schemas.microsoft.com/developer/msbuild/2003"">
+  <ItemGroup>
+    {string.Join(Environment.NewLine, compileElements)}
+  </ItemGroup>
+  <Import Project=""$(MSBuildToolsPath)\Microsoft.CSharp.targets"" />
+</Project>";
+
+        File.WriteAllText(projectCsproj, csprojContent);
+
+        return projectCsproj;
+    }
+}

build/tools.project.json

@@ -1,7 +1,8 @@
 {
   "dependencies": {
     "GitVersion.CommandLine": "3.6.2",
-    "PdbGit": "3.0.38"
+    "PdbGit": "3.0.38",
+    "Octokit.CodeFormatter": "1.0.0-preview"
   },
   "frameworks": {
     "net45": {