bison@2.7: add test

Formula/bison@2.7.rb

@@ -12,4 +12,32 @@ class BisonAT27 < Formula
                           "--prefix=#{prefix}"
     system "make", "install"
   end
+
+  test do
+    (testpath/"test.y").write <<-EOS.undent
+      %{ #include <iostream>
+         using namespace std;
+         extern void yyerror (char *s);
+         extern int yylex ();
+      %}
+      %start prog
+      %%
+      prog:  //  empty
+          |  prog expr '\\n' { cout << "pass"; exit(0); }
+          ;
+      expr: '(' ')'
+          | '(' expr ')'
+          |  expr expr
+          ;
+      %%
+      char c;
+      void yyerror (char *s) { cout << "fail"; exit(0); }
+      int yylex () { cin.get(c); return c; }
+      int main() { yyparse(); }
+    EOS
+    system "#{bin}/bison", "test.y"
+    system ENV.cxx, "test.tab.c", "-o", "test"
+    assert_equal "pass", shell_output("echo \"((()(())))()\" | ./test")
+    assert_equal "fail", shell_output("echo \"())\" | ./test")
+  end
 end