1 files changed, 61 insertions, 0 deletions
diff --git a/test/ruby/test_arity.rb b/test/ruby/test_arity.rb
new file mode 100644
index 0000000000..23c2cd9e67
--- /dev/null
+++ b/test/ruby/test_arity.rb
@@ -0,0 +1,61 @@
+require 'test/unit'
+
+class TestArity < Test::Unit::TestCase
+  def err_mess(method_proc = nil, argc = 0)
+    args = (1..argc).to_a
+    case method_proc
+      when nil
+        yield
+      when Symbol
+        method(method_proc).call(*args)
+      else
+        method_proc.call(*args)
+    end
+    fail "Expected ArgumentError to be raised"
+  rescue ArgumentError => err
+    s = err.to_s
+    assert s =~ /wrong number of arguments \((.*)\)/, "Unexpected ArgumentError's message: #{s}"
+    $1
+  end
+
+  def a
+  end
+
+  def b(a, b, c, d=1, e=2, f, g, h, i, &block)
+  end
+
+  def c(a, b, c, d=1, e=2, *rest)
+  end
+
+  def d(a, b: 42)
+  end
+
+  def e(a, b:42, **c)
+  end
+
+  def f(a, b, c=1, *rest, d: 3)
+  end
+
+  def test_method_err_mess
+    assert_equal "1 for 0",     err_mess(:a, 1)
+    assert_equal "10 for 7..9", err_mess(:b, 10)
+    assert_equal "2 for 3+",    err_mess(:c, 2)
+    assert_equal "2 for 1",     err_mess(:d, 2)
+    assert_equal "0 for 1",     err_mess(:d, 0)
+    assert_equal "2 for 1",     err_mess(:e, 2)
+    assert_equal "0 for 1",     err_mess(:e, 0)
+    assert_equal "1 for 2+",    err_mess(:f, 1)
+  end
+
+  def test_proc_err_mess
+    assert_equal "0 for 1..2",  err_mess(->(b, c=42){}, 0)
+    assert_equal "1 for 2+",    err_mess(->(a, b, c=42, *d){}, 1)
+    assert_equal "3 for 4+",    err_mess(->(a, b, *c, d, e){}, 3)
+    assert_equal "3 for 1..2",  err_mess(->(b, c=42){}, 3)
+    assert_equal "1 for 0",     err_mess(->(&block){}, 1)
+    # Double checking:
+    p = Proc.new{|b, c=42| :ok}
+    assert_equal :ok,  p.call(1, 2, 3)
+    assert_equal :ok,  p.call
+  end
+end