Create Commnad::MultipleTestsNotSupported error

lib/retest/command/base.rb

@@ -1,5 +1,7 @@
 module Retest
   class Command
+    class MultipleTestsNotSupported < StandardError; end
+
     class Base
       def initialize(all: false, file_system: FileSystem, command: nil)
         @file_system = file_system
@@ -36,11 +38,11 @@ def hardcoded_type?
       end
 
       def to_s
-        raise NotImplementedError
+        @command
       end
 
       def format_batch(*files)
-        raise NotImplementedError
+        raise MultipleTestsNotSupported, "Multiple test files run not supported for '#{to_s}'"
       end
 
       private

lib/retest/command/hardcoded.rb

@@ -1,13 +1,5 @@
 module Retest
   class Command
-    class Hardcoded < Base
-      def to_s
-        @command
-      end
-
-      def format_batch(*files)
-        raise ArgumentError, "Multiple test files run not supported for '#{to_s}'"
-      end
-    end
+    class Hardcoded < Base; end
   end
 end

test/retest/command/hardcoded_test.rb

@@ -55,13 +55,13 @@ def test_to_s
       end
 
       def test_format_with_one_file
-        assert_raises(ArgumentError) do
+        assert_raises(Command::MultipleTestsNotSupported) do
           @subject.format_batch('a/file/path.rb')
         end
       end
 
       def test_format_with_multiple_files
-        assert_raises(ArgumentError) do
+        assert_raises(Command::MultipleTestsNotSupported) do
           @subject.format_batch('a/file/path.rb', 'another/file/path.rb')
         end
       end

test/retest/runner_test.rb

@@ -160,7 +160,7 @@ def test_returns_last_command
       end
 
       def test_run_multiple_tests
-        assert_raises(ArgumentError) do
+        assert_raises(Command::MultipleTestsNotSupported) do
           @subject.command = @command
           @subject.format_instruction(test_files: ['file_path.rb', 'file_path_two.rb'])
         end