Current progress

koans/about_methods.rb

@@ -0,0 +1,153 @@
+require File.expand_path(File.dirname(__FILE__) + '/neo')
+
+def my_global_method(a,b)
+  a + b
+end
+
+class AboutMethods < Neo::Koan
+
+  def test_calling_global_methods
+    assert_equal __, my_global_method(2,3)
+  end
+
+  def test_calling_global_methods_without_parentheses
+    result = my_global_method 2, 3
+    assert_equal __, result
+  end
+
+  # (NOTE: We are Using eval below because the example code is
+  # considered to be syntactically invalid).
+  def test_sometimes_missing_parentheses_are_ambiguous
+    eval "assert_equal 5, my_global_method 2, 3" # ENABLE CHECK
+    #
+    # Ruby doesn't know if you mean:
+    #
+    #   assert_equal(5, my_global_method(2), 3)
+    # or
+    #   assert_equal(5, my_global_method(2, 3))
+    #
+    # Rewrite the eval string to continue.
+    #
+  end
+
+  # NOTE: wrong number of arguments is not a SYNTAX error, but a
+  # runtime error.
+  def test_calling_global_methods_with_wrong_number_of_arguments
+    exception = assert_raise(___) do
+      my_global_method
+    end
+    assert_match(/__/, exception.message)
+
+    exception = assert_raise(___) do
+      my_global_method(1,2,3)
+    end
+    assert_match(/__/, exception.message)
+  end
+
+  # ------------------------------------------------------------------
+
+  def method_with_defaults(a, b=:default_value)
+    [a, b]
+  end
+
+  def test_calling_with_default_values
+    assert_equal [1, __], method_with_defaults(1)
+    assert_equal [1, __], method_with_defaults(1, 2)
+  end
+
+  # ------------------------------------------------------------------
+
+  def method_with_var_args(*args)
+    args
+  end
+
+  def test_calling_with_variable_arguments
+    assert_equal __, method_with_var_args.class
+    assert_equal __, method_with_var_args
+    assert_equal __, method_with_var_args(:one)
+    assert_equal __, method_with_var_args(:one, :two)
+  end
+
+  # ------------------------------------------------------------------
+
+  def method_with_explicit_return
+    :a_non_return_value
+    return :return_value
+    :another_non_return_value
+  end
+
+  def test_method_with_explicit_return
+    assert_equal __, method_with_explicit_return
+  end
+
+  # ------------------------------------------------------------------
+
+  def method_without_explicit_return
+    :a_non_return_value
+    :return_value
+  end
+
+  def test_method_without_explicit_return
+    assert_equal __, method_without_explicit_return
+  end
+
+  # ------------------------------------------------------------------
+
+  def my_method_in_the_same_class(a, b)
+    a * b
+  end
+
+  def test_calling_methods_in_same_class
+    assert_equal __, my_method_in_the_same_class(3,4)
+  end
+
+  def test_calling_methods_in_same_class_with_explicit_receiver
+    assert_equal __, self.my_method_in_the_same_class(3,4)
+  end
+
+  # ------------------------------------------------------------------
+
+  def my_private_method
+    "a secret"
+  end
+  private :my_private_method
+
+  def test_calling_private_methods_without_receiver
+    assert_equal __, my_private_method
+  end
+
+  if before_ruby_version("2.7")   # https://github.com/edgecase/ruby_koans/issues/12
+    def test_calling_private_methods_with_an_explicit_receiver
+      exception = assert_raise(___) do
+        self.my_private_method
+      end
+      assert_match /__/, exception.message
+    end
+  end
+
+  # ------------------------------------------------------------------
+
+  class Dog
+    def name
+      "Fido"
+    end
+
+    private
+
+    def tail
+      "tail"
+    end
+  end
+
+  def test_calling_methods_in_other_objects_require_explicit_receiver
+    rover = Dog.new
+    assert_equal __, rover.name
+  end
+
+  def test_calling_private_methods_in_other_objects
+    rover = Dog.new
+    assert_raise(___) do
+      rover.tail
+    end
+  end
+end