Refactor IVcs interface to allow passing working directory

To make the VCS providers more testable.
Add support for changing working directory in the git vcs provider

Author: nover

src/Vcs/Git/GitVcs.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.IO;
 
 namespace Skarp.Version.Cli.Vcs.Git
 {
@@ -10,14 +11,15 @@ public class GitVcs : IVcs
         /// </summary>
         /// <param name="csProjFilePath">Path to the cs project file that was version updated</param>
         /// <param name="message">The message to include in the commit</param>
-        public void Commit(string csProjFilePath, string message)
+        /// <param name="cwd"></param>
+        public void Commit(string csProjFilePath, string message, string cwd = null)
         {
-            if(!LaunchGitWithArgs($"add \"{csProjFilePath}\""))
+            if(!LaunchGitWithArgs($"add \"{csProjFilePath}\"", cwd: cwd))
             {
                 throw new OperationCanceledException($"Unable to add cs proj file {csProjFilePath} to git index");
             }
 
-            if(!LaunchGitWithArgs($"commit -m \"{message}\""))
+            if(!LaunchGitWithArgs($"commit -m \"{message}\"", cwd: cwd))
             {
                 throw new OperationCanceledException("Unable to commit");
             }
@@ -27,42 +29,54 @@ public void Commit(string csProjFilePath, string message)
         /// Determines whether the current repository is clean.
         /// </summary>
         /// <returns></returns>
-        public bool IsRepositoryClean()
+        public bool IsRepositoryClean(string cwd = null)
         {
-            return LaunchGitWithArgs("diff-index --quiet HEAD --");
+            return LaunchGitWithArgs("diff-index HEAD --", cwd: cwd);
         }
 
         /// <summary>
         /// Determines whether git is present in PATH on the current computer
         /// </summary>
         /// <returns></returns>
-        public bool IsVcsToolPresent()
+        public bool IsVcsToolPresent(string cwd = null)
         {
             // launching `git --help` returns exit code 0 where as `git` returns 1 as git wants a cmd line argument
-            return LaunchGitWithArgs("--help");
+            return LaunchGitWithArgs("--help", cwd: cwd);
         }
 
         /// <summary>
         /// Creates a new tag
         /// </summary>
         /// <param name="tagName">Name of the tag</param>
-        public void Tag(string tagName)
+        /// <param name="cwd"></param>
+        public void Tag(string tagName, string cwd = null)
         {
-            if(!LaunchGitWithArgs($"tag {tagName}"))
+            if(!LaunchGitWithArgs($"tag {tagName}", cwd: cwd))
             {
                 throw new OperationCanceledException("Unable to create tag");
             }
         }
 
-        private static bool LaunchGitWithArgs(string args, int waitForExitTimeMs = 1000, int exitCode = 0)
+        /// <summary>
+        /// Helper method for launching git with different arguments while returning just a boolean of whether the
+        /// "command" was successful
+        /// </summary>
+        /// <param name="args">The args to pass onto git, e.g `diff` to launch `git diff`</param>
+        /// <param name="waitForExitTimeMs">How long to wait for the git operation to complete</param>
+        /// <param name="exitCode">The expected exit code</param>
+        /// <param name="cwd">The working directory to change into, if any. Leave null for "current directory" </param>
+        /// <returns></returns>
+        internal static bool LaunchGitWithArgs(
+            string args,
+            int waitForExitTimeMs = 1000, 
+            int exitCode = 0,
+            string cwd = null
+        )
         {
             try
             {
-                var startInfo = CreateGitShellStartInfo(args);
-                var proc = Process.Start(startInfo);
-                proc.WaitForExit(waitForExitTimeMs);
-
-                return proc.ExitCode == exitCode;
+                var (procExitCode, stdOut, stdErr) = LaunchGitWithArgsInner(args, waitForExitTimeMs, cwd);
+                return procExitCode == exitCode;
             }
             catch (Exception ex)
             {
@@ -71,15 +85,36 @@ private static bool LaunchGitWithArgs(string args, int waitForExitTimeMs = 1000,
             }
         }
 
-        private static ProcessStartInfo CreateGitShellStartInfo(string args)
+        internal static (int ExitCode, string stdOut, string stdErr) LaunchGitWithArgsInner(
+            string args,
+            int waitForExitTimeMs,
+            string cwd = null
+        )
         {
-            return new ProcessStartInfo("git")
+            var startInfo = CreateGitShellStartInfo(args, cwd);
+            var proc = Process.Start(startInfo);
+            proc.WaitForExit(waitForExitTimeMs);
+
+            var stdOut = proc.StandardOutput.ReadToEnd();
+            var stdErr = proc.StandardError.ReadToEnd();
+            return (proc.ExitCode, stdOut,stdErr);
+        }
+
+        internal static ProcessStartInfo CreateGitShellStartInfo(string args, string cwd = null)
+        {
+            var procInfo =  new ProcessStartInfo("git")
             {
                 Arguments = args,
                 RedirectStandardError = true,
                 RedirectStandardInput = true,
                 RedirectStandardOutput = true,
             };
+
+            if (!string.IsNullOrWhiteSpace(cwd))
+            {
+                procInfo.WorkingDirectory = cwd;
+            }
+            return procInfo;
         }
 
         public string ToolName()

src/Vcs/IVcs.cs

@@ -16,29 +16,33 @@ public interface IVcs
         /// are available in the current CLI contenxt - i.e check that `git` command can be found
         /// and executed
         /// </summary>
+        /// <param name="cwd">Change working directory - leave null for current directory</param>
         /// <returns><c>true</c> if the tool exists, <c>false</c> otherwise</returns>
-        bool IsVcsToolPresent();
+        bool IsVcsToolPresent(string cwd = null);
 
         /// <summary>
         /// When implemented by a concrete class it returns <c>true</c> if the 
         /// current HEAD of the local repository is clean - i.e no pending changes
         /// </summary>
+        /// <param name="cwd">Change working directory - leave null for current directory</param>
         /// <returns></returns>
-        bool IsRepositoryClean();
+        bool IsRepositoryClean(string cwd = null);
 
         /// <summary>
         /// When implemented by a concrete class it allows to create a commit with the 
         /// changed version in the project file
         /// </summary>
         /// <param name="csProjFilePath">Path to the cs project file</param>
         /// <param name="message">The message to create the commit message with</param>
-        void Commit(string csProjFilePath, string message);
+        /// <param name="cwd">Change working directory - leave null for current directory</param>
+        void Commit(string csProjFilePath, string message, string cwd = null);
 
         /// <summary>
         /// When implemented by a concrete class it will tag the latest commit with the
         /// given tag name
         /// </summary>
         /// <param name="tagName">The name of the tag to create - i.e v1.0.2 </param>
-        void Tag(string tagName);
+        /// <param name="cwd">Change working directory - leave null for current directory</param>
+        void Tag(string tagName, string cwd = null);
     }
 }