Add full chmod support (#18)

This was already supported inside the memory file system adapter. Update the main file system adapter to support this, and expose a public method.

lib/dry/files.rb

@@ -82,6 +82,25 @@ def write(path, *content)
       adapter.write(path, *content)
     end
 
+    # Sets UNIX permissions of the file at the given path.
+    #
+    # Accepts permissions in numeric mode only, best provided as octal numbers matching the
+    # standard UNIX octal permission modes, such as `0o544` for a file writeable by its owner and
+    # readable by others, or `0o755` for a file writeable by its owner and executable by everyone.
+    #
+    # @param path [String,Pathname] the path to the file
+    # @param mode [Integer] the UNIX permissions mode
+    #
+    # @raise [Dry::Files::IOError] in case of I/O error
+    #
+    # @since 1.1.0
+    # @api public
+    def chmod(path, mode)
+      raise Dry::Files::Error, "mode should be an integer (e.g. 0o755)" unless mode.is_a?(Integer)
+
+      adapter.chmod(path, mode)
+    end
+
     # Returns a new string formed by joining the strings using Operating
     # System path separator
     #

lib/dry/files/file_system.rb

@@ -131,6 +131,25 @@ def write(path, *content)
         end
       end
 
+      # Sets UNIX permissions of the file at the given path.
+      #
+      # Accepts permissions in numeric mode only, best provided as octal numbers matching the
+      # standard UNIX octal permission modes, such as `0o544` for a file writeable by its owner and
+      # readable by others, or `0o755` for a file writeable by its owner and executable by everyone.
+      #
+      # @param path [String,Pathname] the path to the file
+      # @param mode [Integer] the UNIX permissions mode
+      #
+      # @raise [Dry::Files::IOError] in case of I/O error
+      #
+      # @since 1.1.0
+      # @api private
+      def chmod(path, mode)
+        with_error_handling do
+          file_utils.chmod(mode, path)
+        end
+      end
+
       # Returns a new string formed by joining the strings using Operating
       # System path separator
       #

spec/integration/dry/files_spec.rb

@@ -124,6 +124,41 @@
     end
   end
 
+  describe "#chmod" do
+    it "sets the given permissions" do
+      path = root.join("permissions")
+      subject.touch(path)
+      mode = path.stat.mode
+
+      begin
+        expect { subject.chmod(path, 0o755) }
+          .to change { path.executable? }.to true
+
+        expect { subject.chmod(path, 0o644) }
+          .to change { path.executable? }.to false
+      ensure
+        path.chmod(mode)
+      end
+    end
+
+    it "raises an argument error when the permissions are given in non-numeric format" do
+      path = root.join("permissions")
+
+      expect { subject.chmod(path, "+x") }
+        .to raise_error Dry::Files::Error, "mode should be an integer (e.g. 0o755)"
+    end
+
+    it "raises an error when the path doesn't exist" do
+      path = root.join("permissions-does-not-exist")
+
+      expect { subject.chmod(path, 0o755) }.to raise_error do |exception|
+        expect(exception).to be_kind_of(Dry::Files::IOError)
+        expect(exception.cause).to be_kind_of(Errno::ENOENT)
+        expect(exception.message).to include(path.to_s)
+      end
+    end
+  end
+
   describe "#cp" do
     let(:source) { root.join("..", "source") }