Binding assertions

Author: joeldrapper

lib/literal.rb

@@ -19,6 +19,48 @@ module Literal
 		loader.setup
 	end
 
+	CLASS_METHOD = Kernel.instance_method(:class)
+	CLASS_VARIABLE_GET_METHOD = Module.instance_method(:class_variable_get)
+	INSTANCE_VARIABLE_GET_METHOD = Kernel.instance_method(:instance_variable_get)
+
+	module BindingAssert
+		def assert(**kwargs)
+			kwargs.each do |name, type|
+				string_name = (Symbol === name) ? name.name : name
+				first_byte = string_name.getbyte(0)
+
+				if first_byte == 64 # @foo
+					if string_name.getbyte(1) == 64 # @@foo
+						value = CLASS_VARIABLE_GET_METHOD.bind_call(
+							CLASS_METHOD.bind_call(receiver), name
+						)
+					else # @foo
+						value = INSTANCE_VARIABLE_GET_METHOD.bind_call(receiver, name)
+					end
+				elsif first_byte == 36 # $foo
+					raise if string_name.match?(/[\s\.]/)
+					value = eval(string_name)
+				else # foo
+					value = local_variable_get(name)
+				end
+
+				unless type === value
+					raise ::TypeError.new(<<~MESSAGE)
+						Assertion failed!
+
+						  #{name}
+						    Expected: #{type.inspect}
+						    Actual (#{value.class}): #{value.inspect}
+					MESSAGE
+				end
+			end
+		end
+	end
+
+	::Binding.include(Literal::BindingAssert)
+
+
+
 	def self.Value(*args, **kwargs, &block)
 		value_class = Class.new(Literal::Value)
 

test/assert.test.rb

@@ -0,0 +1,50 @@
+$a = 1
+
+test "assert with local variable" do
+	refute_raises do
+		a = 1
+		b = "Hello"
+
+		binding.assert(a: Integer, b: String)
+		binding.assert("a" => Integer, "b" => String)
+	end
+
+	assert_raises Literal::TypeError do
+		a = 1
+		binding.assert(a: String)
+	end
+end
+
+test "assert with global variable" do
+	refute_raises do
+		binding.assert("$a": Integer)
+	end
+
+	assert_raises Literal::TypeError do
+		binding.assert("$a": String)
+	end
+end
+
+test "assert with instance variable" do
+	refute_raises do
+		@a = 1
+		binding.assert("@a": Integer)
+	end
+
+	assert_raises Literal::TypeError do
+		@a = 1
+		binding.assert("@a": String)
+	end
+end
+
+test "assert with class variable" do
+	refute_raises do
+		@@a = 1
+		binding.assert("@@a": Integer)
+	end
+
+	assert_raises Literal::TypeError do
+		@@a = 1
+		binding.assert("@@a": String)
+	end
+end