Allow to configure formatter via configuration file

closes #20

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2017 Vitalii Elenhaupt
+Copyright (c) 2018 Vitalii Elenhaupt
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

spec/ameba/cli/cmd_spec.cr

@@ -3,10 +3,6 @@ require "../../../src/ameba/cli/cmd"
 
 module Ameba::Cli
   describe "Cmd" do
-    it "has a list of available formatters" do
-      AVAILABLE_FORMATTERS.should_not be_nil
-    end
-
     describe ".run" do
       it "runs ameba" do
         r = Cli.run %w(-f silent file.cr)
@@ -58,7 +54,7 @@ module Ameba::Cli
 
       it "allows args to be blank" do
         c = Cli.parse_args [] of String
-        c.formatter.should eq :progress
+        c.formatter.should be_nil
         c.files.should be_nil
         c.only.should be_nil
         c.except.should be_nil

spec/ameba/config_spec.cr

@@ -4,6 +4,10 @@ module Ameba
   describe Config do
     config_sample = "config/ameba.yml"
 
+    it "should have a list of available formatters" do
+      Config::AVAILABLE_FORMATTERS.should_not be_nil
+    end
+
     describe ".load" do
       it "loads custom config" do
         config = Config.load config_sample
@@ -45,6 +49,17 @@ module Ameba
         config.formatter = formatter
         config.formatter.should eq formatter
       end
+
+      it "allows to set formatter using a name" do
+        config.formatter = :progress
+        config.formatter.should_not be_nil
+      end
+
+      it "raises an error if not available formatter is set" do
+        expect_raises(Exception) do
+          config.formatter = :no_such_formatter
+        end
+      end
     end
 
     describe "#update_rule" do

src/ameba/cli/cmd.cr

@@ -5,13 +5,6 @@ require "option_parser"
 module Ameba::Cli
   extend self
 
-  AVAILABLE_FORMATTERS = {
-    progress: Formatter::DotFormatter,
-    todo:     Formatter::TODOFormatter,
-    flycheck: Formatter::FlycheckFormatter,
-    silent:   Formatter::BaseFormatter,
-  }
-
   def run(args)
     opts = parse_args args
     config = Config.load opts.config
@@ -28,7 +21,7 @@ module Ameba::Cli
 
   private class Opts
     property config = Config::PATH
-    property formatter : String | Symbol = :progress
+    property formatter : Symbol | String | Nil
     property files : Array(String)?
     property only : Array(String)?
     property except : Array(String)?
@@ -49,7 +42,7 @@ module Ameba::Cli
       end
 
       parser.on("-f", "--format FORMATTER",
-        "Choose an output formatter: #{formatters}") do |formatter|
+        "Choose an output formatter: #{Config.formatter_names}") do |formatter|
         opts.formatter = formatter
       end
 
@@ -86,17 +79,11 @@ module Ameba::Cli
   end
 
   private def configure_formatter(config, opts)
-    if cls = AVAILABLE_FORMATTERS[opts.formatter]?
-      config.formatter = cls.new
-    else
-      raise "Unknown formatter `#{opts.formatter}`. Use any of #{formatters}."
+    if name = opts.formatter
+      config.formatter = name
     end
   end
 
-  private def formatters
-    AVAILABLE_FORMATTERS.keys.join("|")
-  end
-
   private def print_version
     puts VERSION
     exit 0

src/ameba/config.cr

@@ -12,6 +12,13 @@ require "yaml"
 # By default config loads `.ameba.yml` file in a current directory.
 #
 class Ameba::Config
+  AVAILABLE_FORMATTERS = {
+    progress: Formatter::DotFormatter,
+    todo:     Formatter::TODOFormatter,
+    flycheck: Formatter::FlycheckFormatter,
+    silent:   Formatter::BaseFormatter,
+  }
+
   PATH = ".ameba.yml"
   setter formatter : Formatter::BaseFormatter?
   setter files : Array(String)?
@@ -22,6 +29,10 @@ class Ameba::Config
   # `Config.load` uses this constructor to instantiate new config by YAML file.
   protected def initialize(@config : YAML::Any)
     @rules = Rule.rules.map &.new(config)
+
+    if @config.as_h? && (name = @config["Formatter"]?.try &.["Name"]?)
+      self.formatter = name.to_s
+    end
   end
 
   # Loads YAML configuration file by `path`.
@@ -33,8 +44,12 @@ class Ameba::Config
   def self.load(path = PATH)
     content = File.exists?(path) ? File.read path : ""
     Config.new YAML.parse(content)
-  rescue
-    raise "Config file is invalid"
+  rescue e
+    raise "Config file is invalid: #{e.message}"
+  end
+
+  def self.formatter_names
+    AVAILABLE_FORMATTERS.keys.join("|")
   end
 
   # Returns a list of paths (with wildcards) to files.
@@ -64,6 +79,21 @@ class Ameba::Config
     @formatter ||= default_formatter
   end
 
+  # Sets formatter by name.
+  #
+  # ```
+  # config = Ameba::Config.load
+  # config.formatter = :progress
+  # ```
+  #
+  def formatter=(name : String | Symbol)
+    if f = AVAILABLE_FORMATTERS[name]?
+      @formatter = f.new
+    else
+      raise "Unknown formatter `#{name}`. Use one of #{Config.formatter_names}."
+    end
+  end
+
   # Updates rule properties.
   #
   # ```