Add analyzer for leap exercise (#105)

Author: PatrickMcSweeny

lib/analyzer.rb

@@ -1,11 +1,13 @@
 EXERCISES = %w[
   two_fer
   acronym
+  leap
 ].freeze
 
 FILENAMES = {
   "acronym" => "acronym.rb",
-  "two-fer" => "two_fer.rb"
+  "two-fer" => "two_fer.rb",
+  "leap" => "leap.rb"
 }.freeze
 
 require 'mandate'

lib/analyzers/leap/analyze.rb

@@ -0,0 +1,16 @@
+module Leap
+  class Analyze < ExerciseAnalyzer
+    include Mandate
+
+    def analyze!
+      if solution.uses_std_lib?
+        self.status = :disapprove
+        self.comments = ["ruby.leap.std_lib"]
+      else
+        self.status = :refer_to_mentor
+      end
+
+      raise FinishedFlowControlException
+    end
+  end
+end

lib/analyzers/leap/representation.rb

@@ -0,0 +1,19 @@
+module Leap
+  class Representation < SolutionRepresentation
+    def uses_std_lib?
+      date_node = SA::Helpers.extract_nodes(:const, target_method).find { |node| node.const_name == 'Date' }
+      return false if date_node.nil?
+
+      date_node.parent.children.any? { |node| %i[leap? gregorian_leap? julian_leap?].include? node }
+    end
+
+    private
+    def target_module
+      SA::Helpers.extract_module_or_class(root_node, "Year")
+    end
+
+    def target_method
+      SA::Helpers.extract_module_method(target_module, "leap?")
+    end
+  end
+end

test/exercises/leap_test.rb

@@ -0,0 +1,59 @@
+require "test_helper"
+
+class LeapTest < Minitest::Test
+  def test_date_leap_method_is_disapproved
+    source = <<~SOURCE
+      class Year
+        def self.leap?(year)
+          Date.leap?(year)
+        end
+      end
+    SOURCE
+
+    results = Leap::Analyze.(source)
+    assert_equal :disapprove, results[:status]
+    assert_equal ["ruby.leap.std_lib"], results[:comments]
+  end
+
+  def test_date_julian_leap_method_is_disapproved
+    source = <<~SOURCE
+      class Year
+        def self.leap?(year)
+          Date.julian_leap?(year)
+        end
+      end
+    SOURCE
+
+    results = Leap::Analyze.(source)
+    assert_equal :disapprove, results[:status]
+    assert_equal ["ruby.leap.std_lib"], results[:comments]
+  end
+
+  def test_date_gregorian_leap_method_is_disapproved
+    source = <<~SOURCE
+      class Year
+        def self.leap?(year)
+          Date.gregorian_leap?(year)
+        end
+      end
+    SOURCE
+
+    results = Leap::Analyze.(source)
+    assert_equal :disapprove, results[:status]
+    assert_equal ["ruby.leap.std_lib"], results[:comments]
+  end
+
+  def test_custom_implementation_referred_to_mentor
+    source = <<~SOURCE
+      class Year
+        def self.leap?(year)
+          year % 4 == 0
+        end
+      end
+    SOURCE
+
+    results = Leap::Analyze.(source)
+    assert_equal :refer_to_mentor, results[:status]
+    assert_empty results[:comments]
+  end
+end