Fix crash on an endless method with empty parentheses (#361)

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Fixed
+- Fix crash when formatting an endless method with empty parentheses (`def foo() = 1`). ([#362](https://github.com/ruby-formatter/rufo/pull/362))
 
 ### Changed
 

lib/rufo/formatter.rb

@@ -2015,6 +2015,9 @@ def visit_def_from_name(name, params, body)
         check :on_rparen
         next_token
         write "()"
+        # Consume the space after `)` like the other branches do, so an endless
+        # method body (`def foo() = 1`) is detected below instead of crashing.
+        skip_space
       else
         write "("
 

spec/lib/rufo/formatter_source_specs/endless_methods.rb.spec

@@ -15,3 +15,15 @@ def foo = puts(    "a")
 
 #~# EXPECTED
 def foo = puts("a")
+
+#~# ORIGINAL format_endless_method_with_empty_params
+def foo() = 1
+
+#~# EXPECTED
+def foo() = 1
+
+#~# ORIGINAL format_endless_method_with_empty_params_and_spacing
+def foo()   =    1
+
+#~# EXPECTED
+def foo() = 1