Mostly implemented progress formatter

src/spectator/formatting/progress_formatter.cr

@@ -1,8 +1,37 @@
+require "colorize"
 require "./formatter"
 
 module Spectator::Formatting
   # Output formatter that produces a single character for each test as it completes.
-  # A '.' indicates a pass, 'F' a failure, and '*' a skipped or pending test.
+  # A '.' indicates a pass, 'F' a failure, 'E' an error, and '*' a skipped or pending test.
   class ProgressFormatter < Formatter
+    @pass_char : Colorize::Object(Char) = '.'.colorize(:green)
+    @fail_char : Colorize::Object(Char) = 'F'.colorize(:red)
+    @error_char : Colorize::Object(Char) = 'E'.colorize(:red)
+    @skip_char : Colorize::Object(Char) = '*'.colorize(:yellow)
+
+    # Creates the formatter.
+    def initialize(@io : IO = STDOUT)
+    end
+
+    # Produces a pass character.
+    def example_passed(_notification)
+      @pass_char.to_s(@io)
+    end
+
+    # Produces a fail character.
+    def example_failed(_notification)
+      @fail_char.to_s(@io)
+    end
+
+    # Produces an error character.
+    def example_error(_notification)
+      @error_char.to_s(@io)
+    end
+
+    # Produces a skip character.
+    def example_pending(_notification)
+      @skip_char.to_s(@io)
+    end
   end
 end