Fix README custom printer example and abstract printer write method

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Change log
 
+## Unreleased
+
+### Fixed
+* Add missing `class` keyword to README example for custom printers
+* Pass command argument to abstract printer writer method calls
+
 ## [v0.10.1] - 2021-02-14
 
 ### Fixed

README.md

@@ -607,7 +607,7 @@ Please see [lib/tty/command/printers/abstract.rb](https://github.com/piotrmurach
 At the very minimum you need to specify the `write` method that will be called during the lifecycle of command execution. The `write` accepts two arguments, first the currently run command instance and second the message to be printed:
 
 ```ruby
-CustomPrinter < TTY::Command::Printers::Abstract
+class CustomPrinter < TTY::Command::Printers::Abstract
   def write(cmd, message)
     puts cmd.to_command + message
   end

lib/tty/command/printers/abstract.rb

@@ -28,19 +28,19 @@ def initialize(output, options = {})
         end
 
         def print_command_start(cmd, *args)
-          write(cmd.to_command + "#{args.join}")
+          write(cmd, args.join(" "))
         end
 
         def print_command_out_data(cmd, *args)
-          write(args.join(" "))
+          write(cmd, args.join(" "))
         end
 
         def print_command_err_data(cmd, *args)
-          write(args.join(" "))
+          write(cmd, args.join(" "))
         end
 
         def print_command_exit(cmd, *args)
-          write(args.join(" "))
+          write(cmd, args.join(" "))
         end
 
         def write(cmd, message)

spec/unit/printers/custom_spec.rb

@@ -5,20 +5,20 @@
 
   before do
     stub_const("CustomPrinter", Class.new(TTY::Command::Printers::Abstract) do
-      def write(message)
-        output << message
+      def write(cmd, message)
+        output << "#{cmd.to_command}#{message}"
       end
     end)
   end
 
   it "prints command start" do
     printer = CustomPrinter.new(output)
-    cmd = TTY::Command::Cmd.new(:echo, "'hello world'")
+    cmd = TTY::Command::Cmd.new(:echo, "hello world")
 
     printer.print_command_start(cmd)
     output.rewind
 
-    expect(output.string).to eq("echo \\'hello\\ world\\'")
+    expect(output.string).to eq("echo hello\\ world")
   end
 
   it "prints command stdout data" do
@@ -28,7 +28,7 @@ def write(message)
     printer.print_command_out_data(cmd, "data")
     output.rewind
 
-    expect(output.string).to eq("data")
+    expect(output.string).to eq("echo hello\\ worlddata")
   end
 
   it "prints command exit" do
@@ -38,7 +38,7 @@ def write(message)
     printer.print_command_exit(cmd)
     output.rewind
 
-    expect(output.string).to be_empty
+    expect(output.string).to eq("echo hello\\ world")
   end
 
   it "accepts options" do