Add tests for sample dir and tweak samples

Samples are tweaked

- not to raise "TypeError: scan() yielded String (must be Array[2])"
- allow both script usage and lib usage by adding $0 check

sample/array2.y

@@ -27,15 +27,15 @@ end
       when /\A\s+/
         str = $'
       when /\A\w+/
-        yield :ITEM, $&
+        yield [:ITEM, $&]
         str = $'
       else
         c = str[0,1]
-        yield c, c
+        yield [c, c]
         str = str[1..-1]
       end
     end
-    yield false, '$'   # is optional from Racc 1.3.7
+    yield [false, '$']   # is optional from Racc 1.3.7
   end
 
   def next_token

sample/calc.y

@@ -48,18 +48,20 @@ end
 
 ---- footer
 
-parser = Calcp.new
-puts
-puts 'type "Q" to quit.'
-puts
-while true
+if $0 == __FILE__
+  parser = Calcp.new
   puts
-  print '? '
-  str = gets.chop!
-  break if /q/i =~ str
-  begin
-    puts "= #{parser.parse(str)}"
-  rescue ParseError
-    puts $!
+  puts 'type "Q" to quit.'
+  puts
+  while true
+    puts
+    print '? '
+    str = gets.chop!
+    break if /q/i =~ str
+    begin
+      puts "= #{parser.parse(str)}"
+    rescue ParseError
+      puts $!
+    end
   end
 end

sample/hash.y

@@ -29,18 +29,18 @@ end
       when /\A\s+/
         str = $'
       when /\A\w+/
-        yield :IDENT, $&
+        yield [:IDENT, $&]
         str = $'
       when /\A=>/
-        yield '=>', '=>'
+        yield ['=>', '=>']
         str = $'
       else
         c = str[0,1]
-        yield c, c
+        yield [c, c]
         str = str[1..-1]
       end
     end
-    yield false, '$'   # is optional from Racc 1.3.7
+    yield [false, '$']   # is optional from Racc 1.3.7
   end
 
 ---- footer

test/case.rb

@@ -11,6 +11,7 @@
 module Racc
   class TestCase < Test::Unit::TestCase
     PROJECT_DIR = File.expand_path(File.join(__dir__, '..'))
+    SAMPLE_DIR = File.join(PROJECT_DIR, 'sample')
 
     test_dir = File.join(PROJECT_DIR, 'test')
     test_dir = File.join(PROJECT_DIR, 'racc') unless File.exist?(test_dir)

test/test_sample.rb

@@ -0,0 +1,80 @@
+require File.expand_path('lib/helper', __dir__)
+
+module Racc
+  class TestSample < TestCase
+    # working samples
+    [
+      {
+        grammar_file: "array.y",
+        parser_class: :ArrayParser,
+        testcases: [
+          { input: "[1]", expected: ["1"] },
+          { input: "[1, 2]", expected: ["1", "2"] },
+        ]
+      },
+      {
+        grammar_file: "array2.y",
+        parser_class: :ArrayParser2,
+        testcases: [
+          { input: "[1]", expected: ["1"] },
+          { input: "[1, 2]", expected: ["1", "2"] },
+        ]
+      },
+      {
+        grammar_file: "calc.y",
+        parser_class: :Calcp,
+        testcases: [
+          { input: "1", expected: 1 },
+          { input: "10", expected: 10 },
+          { input: "2 + 1", expected: 3 },
+          { input: "2 - 1", expected: 1 },
+          { input: "3 * 4", expected: 12 },
+          { input: "4 / 2", expected: 2 },
+          { input: "3 / 2", expected: 1 },
+          { input: "2 + 3 * 4", expected: 14 },
+          { input: "(2 + 3) * 4", expected: 20 },
+          { input: "2 + (3 * 4)", expected: 14 },
+        ]
+      },
+      {
+        grammar_file: "hash.y",
+        parser_class: :HashParser,
+        testcases: [
+          { input: "{}", expected: {} },
+          { input: "{ a => b }", expected: { "a" => "b" } },
+          { input: "{ a => b, 1 => 2 }", expected: { "a" => "b", "1" => "2" } },
+        ]
+      },
+    ].each do |data|
+      define_method "test_#{data[:grammar_file]}" do
+        outfile = compile_sample(data[:grammar_file])
+
+        load(outfile)
+
+        parser_class = Object.const_get(data[:parser_class])
+        data[:testcases].each do |testcase|
+          input = testcase[:input]
+          actual = parser_class.new.parse(input)
+          expected = testcase[:expected]
+          assert_equal(expected, actual, "expected #{expected} but got #{actual} when input is #{input}")
+        end
+      ensure
+        remove_const_f(data[:parser_class])
+      end
+    end
+
+    private
+
+    # returns the generated file's path
+    def compile_sample(yfile)
+      file = File.basename(yfile, '.y')
+      out = File.join(@OUT_DIR, file)
+      ruby RACC, File.join(SAMPLE_DIR, yfile), "-o#{out}"
+      out
+    end
+
+    def remove_const_f(const_name)
+      Object.send(:remove_const, const_name) if Object.const_defined?(const_name, false)
+    end
+  end
+end