Don't use chdir (exercism#7908)

Author: iHiD

app/commands/user/github_solution_syncer/create_pull_request.rb

@@ -36,19 +36,18 @@ def base_sha
       client.branch(repo_full_name, base_branch).commit.sha
     rescue Octokit::NotFound
       # If it doesn't, then this is a naked repo, so create it.
-      Dir.mktmpdir do |dir|
-        @path = dir
+      WithGitContext.() do |git|
         # No existing branch so create it
-        git "init", "-b", base_branch
+        git.("init", "-b", base_branch)
 
         # Make sure we have the right user set
-        git "config", "user.name", "Exercism's Solution Syncer Bot"
-        git "config", "user.email", "211797793+exercism-solutions-syncer[bot]@users.noreply.github.com"
+        git.("config", "user.name", "Exercism's Solution Syncer Bot")
+        git.("config", "user.email", "211797793+exercism-solutions-syncer[bot]@users.noreply.github.com")
 
         # Make an empty commit and push it
-        git "commit", "--allow-empty", "-m", "Initial empty commit"
-        git "remote", "add", "origin", repo_url
-        git "push", "origin", base_branch
+        git.("commit", "--allow-empty", "-m", "Initial empty commit")
+        git.("remote", "add", "origin", repo_url)
+        git.("push", "origin", base_branch)
       end
 
       client.branch(repo_full_name, base_branch).commit.sha
@@ -57,12 +56,6 @@ def base_sha
     memoize
     def base_branch = client.repository(repo_full_name).default_branch
 
-    def git(*args)
-      Dir.chdir(@path) do
-        system("git", *args, exception: true)
-      end
-    end
-
     def repo_url = "https://x-access-token:#{token}@github.com/#{repo_full_name}.git"
 
     memoize

app/commands/user/github_solution_syncer/local_git_repo.rb

@@ -14,6 +14,7 @@ def update
 
       Dir.mktmpdir do |dir|
         @path = dir
+
         clone_repo
         create_branch
         yield self if block_given?
@@ -51,7 +52,8 @@ def base_branch_name
     def repo = syncer.repo_full_name
 
     def clone_repo
-      git("clone", "--depth=1", repo_url, ".")
+      # Manually do this as we don't want the working dir logic
+      system("git", "clone", "--depth=1", repo_url, @path, exception: true)
 
       # Make sure we have the right user set
       git "config", "user.name", "Exercism's Solution Syncer Bot"
@@ -80,9 +82,9 @@ def push_branch
     end
 
     def git(*args)
-      Dir.chdir(@path) do
-        system("git", *args, exception: true)
-      end
+      git_dir = File.join(@path, '.git')
+      work_tree = @path
+      system("git", "--git-dir=#{git_dir}", "--work-tree=#{work_tree}", *args, exception: true)
     end
 
     def repo_url

app/commands/user/github_solution_syncer/with_git_context.rb

@@ -0,0 +1,26 @@
+class User::GithubSolutionSyncer
+  class WithGitContext
+    include Mandate
+
+    def initialize(&block)
+      @block = block
+    end
+
+    def call
+      # If it doesn't, then this is a naked repo, so create it.
+      Dir.mktmpdir do |dir|
+        git_dir = File.join(dir, '.git')
+        work_tree = dir
+
+        git = lambda do |*args|
+          system("git", "--git-dir=#{git_dir}", "--work-tree=#{work_tree}", *args, exception: true)
+        end
+
+        block.(git)
+      end
+    end
+
+    private
+    attr_reader :block
+  end
+end