Support Ruby method names and operator overrides, including Unicode

Fixes #253

This patch contains these changes:

* Add 50+ new Ruby tests for method name/operator override matching.
* Unicode method names are now supported (#253).
* `=` method name postfixes are now supported.
* These operator overrides are now supported:
  `<`, `<=`, `!` `!@`, `~@`, `!`, `!=`, `!~`, `=~`
* The `<>` "operator" override is removed. It appears that this was
  a typo in the regular expression (`<=?>` should have been `<=>?`).

Syntax verified with https://docs.ruby-lang.org/en/2.7.0/syntax/methods_rdoc.html

1 files changed, 38 insertions, 2 deletions

diff --git a/tests/test_ruby.py b/tests/test_ruby.py
index 86a9ee77..9697bea8 100644
--- a/tests/test_ruby.py
+++ b/tests/test_ruby.py
@@ -9,8 +9,8 @@
 
 import pytest
 
-from pygments.token import Operator, Number, Text, Token
-from pygments.lexers import RubyLexer
+from pygments.token import Name, Number, Operator, Text, Token
+from pygments.lexers.ruby import RubyLexer
 
 
 @pytest.fixture(scope='module')
@@ -147,3 +147,39 @@ def test_escaped_bracestring(lexer):
         (Token.Text, u'\n'),
     ]
     assert list(lexer.get_tokens(fragment)) == tokens
+
+
+@pytest.mark.parametrize(
+    'method_name',
+    (
+        # Bare, un-scoped method names
+        'a', 'A', 'z', 'Z', 'は', '\u0080', '\uffff',
+        'aは0_', 'はA__9', '\u0080はa0_', '\uffff__99Z',
+
+        # Method names with trailing characters
+        'aは!', 'はz?', 'はa=',
+
+        # Scoped method names
+        'self.a', 'String.は_', 'example.AZ09_!',
+
+        # Operator overrides
+        '+', '+@', '-', '-@', '!', '!@', '~', '~@',
+        '*', '**', '/', '%', '&', '^', '`',
+        '<=>', '<', '<<', '<=', '>', '>>', '>=',
+        '==', '!=', '===', '=~', '!~',
+        '[]', '[]=',
+    )
+)
+def test_positive_method_names(lexer, method_name):
+    """Validate positive method name parsing."""
+
+    text = 'def ' + method_name
+    assert list(lexer.get_tokens(text))[-2] == (Name.Function, method_name.rpartition('.')[2])
+
+
+@pytest.mark.parametrize('method_name', ('1', '_', '<>', '<<=', '>>=', '&&', '||', '==?', '==!', '===='))
+def test_negative_method_names(lexer, method_name):
+    """Validate negative method name parsing."""
+
+    text = 'def ' + method_name
+    assert list(lexer.get_tokens(text))[-2] != (Name.Function, method_name)