add dotfiles option

lib/rails/diff/cli.rb

@@ -27,6 +27,15 @@ def file(*files)
         options[:fail] ? abort(diff) : puts(diff)
       end
 
+      desc "dotfiles", "Compare dotfiles in your repository with Rails' generated versions"
+      def dotfiles
+        dotfiles = Dir.glob("**/.*").reject do |path|
+          path.start_with?(".git") || path.include?("/.git/")
+        end
+
+        file(*dotfiles)
+      end
+
       desc "generated GENERATOR [args]", "Compare files that would be created by a Rails generator"
       option :skip, type: :array, desc: "Skip specific files or directories", aliases: ["-s"], default: []
       option :only, type: :array, desc: "Only include specific files or directories", aliases: ["-o"], default: []

spec/lib/rails/diff/cli_spec.rb

@@ -0,0 +1,59 @@
+require "rspec"
+require "rails/diff/cli"
+
+RSpec.describe Rails::Diff::CLI do
+  let(:cli) { described_class.new }
+  let(:mock_diff) { "Mocked diff output" }
+
+  before do
+    allow(Rails::Diff).to receive(:file).and_return(mock_diff)
+  end
+
+  describe "#file" do
+    context "when no files are provided" do
+      it "aborts with an error message" do
+        expect { cli.file }.to raise_error(SystemExit, "Please provide at least one file to compare")
+      end
+    end
+
+    context "when files are provided" do
+      it "outputs the diff if differences exist" do
+        expect { cli.file("file1.rb", "file2.rb") }.to output("#{mock_diff}\n").to_stdout
+      end
+
+      it "aborts if differences exist and fail option is set" do
+        cli.options = { fail: true }
+        expect { cli.file("file1.rb", "file2.rb") }.to raise_error(SystemExit, mock_diff)
+      end
+    end
+  end
+
+  describe "#dotfiles" do
+    let(:mock_dotfiles) { [".env", ".gitignore"] }
+
+    before do
+      allow(Dir).to receive(:glob).with("**/.*").and_return(mock_dotfiles)
+      allow(mock_dotfiles).to receive(:reject).and_return(mock_dotfiles)
+    end
+
+    context "when no dotfiles are found" do
+      before do
+        allow(Dir).to receive(:glob).with("**/.*").and_return([])
+      end
+
+      it "does not output anything" do
+        expect { cli.dotfiles }.to_not output.to_stdout
+      end
+    end
+
+    context "when dotfiles are found and differences exist" do
+      before do
+        allow(Rails::Diff).to receive(:file).and_return(mock_diff)
+      end
+
+      it "outputs the diff" do
+        expect { cli.dotfiles }.to output("#{mock_diff}\n").to_stdout
+      end
+    end
+  end
+end