diff --git a/core/symbol.rbs b/core/symbol.rbs
index da9d75801..fafd9c578 100644
--- a/core/symbol.rbs
+++ b/core/symbol.rbs
@@ -131,9 +131,7 @@ class Symbol
   #     Symbol.all_symbols.size    # => 9334
   #     Symbol.all_symbols.take(3) # => [:!, :"\"", :"#"]
   #
-  def self.all_symbols: () -> ::Array[Symbol]
-
-  public
+  def self.all_symbols: () -> Array[Symbol]
 
   # <!--
   #   rdoc-file=string.c
@@ -152,8 +150,8 @@ class Symbol
   #
   # Related: String#<=>.
   #
-  def <=>: (Symbol other) -> Integer
-         | (untyped other) -> Integer?
+  def <=>: (Symbol object) -> (-1 | 0 | 1)
+         | (untyped) -> nil
 
   # <!--
   #   rdoc-file=string.c
@@ -161,12 +159,12 @@ class Symbol
   # -->
   # Returns `true` if `object` is the same object as `self`, `false` otherwise.
   #
-  def ==: (untyped obj) -> bool
+  def ==: (untyped object) -> bool
 
   # <!-- rdoc-file=string.c -->
   # Returns `true` if `object` is the same object as `self`, `false` otherwise.
   #
-  def ===: (untyped obj) -> bool
+  alias === ==
 
   # <!--
   #   rdoc-file=string.c
@@ -176,7 +174,7 @@ class Symbol
   # variables; see String#=~.
   #
   def =~: (Regexp regex) -> Integer?
-        | [T] (String::_MatchAgainst[self, T] object) -> T
+        | [T] (String::_MatchAgainst[String, T] object) -> T
 
   # <!--
   #   rdoc-file=string.c
@@ -188,12 +186,10 @@ class Symbol
   # -->
   # Equivalent to `symbol.to_s[]`; see String#[].
   #
-  def []: (int index) -> String?
-        | (int start, int length) -> String?
-        | (Range[Integer?] range) -> String?
-        | (Regexp regexp) -> String?
-        | (Regexp regexp, int | String capture) -> String?
-        | (String match_str) -> String?
+  def []: (int start, ?int length) -> String?
+        | (range[int?] range) -> String?
+        | (Regexp regexp, ?MatchData::capture backref) -> String?
+        | (String substring) -> String?
 
   # <!--
   #   rdoc-file=string.c
@@ -240,7 +236,8 @@ class Symbol
   #
   # Related: Symbol#casecmp?, String#casecmp.
   #
-  def casecmp: (untyped other) -> Integer?
+  def casecmp: (Symbol object) -> (-1 | 0 | 1)?
+             | (untyped) -> nil
 
   # <!--
   #   rdoc-file=string.c
@@ -273,7 +270,8 @@ class Symbol
   #
   # Related: Symbol#casecmp, String#casecmp?.
   #
-  def casecmp?: (untyped other) -> bool?
+  def casecmp?: (Symbol object) -> bool?
+              | (untyped) -> nil
 
   # <!--
   #   rdoc-file=string.c
@@ -321,7 +319,7 @@ class Symbol
   #
   # Related: Symbol#inspect, Symbol#name.
   #
-  def id2name: () -> String
+  alias id2name to_s
 
   # <!--
   #   rdoc-file=string.c
@@ -340,7 +338,7 @@ class Symbol
   #   - intern()
   # -->
   #
-  def intern: () -> Symbol
+  alias intern to_sym
 
   # <!--
   #   rdoc-file=string.c
@@ -358,8 +356,8 @@ class Symbol
   # Equivalent to `self.to_s.match`, including possible updates to global
   # variables; see String#match.
   #
-  def match: (Regexp | string pattern, ?int pos) -> MatchData?
-           | (Regexp | string pattern, ?int pos) { (MatchData) -> void } -> untyped
+  def match: (Regexp | string pattern, ?int offset) -> MatchData?
+           | [T] (Regexp | string pattern, ?int offset) { (MatchData matchdata) -> T } -> T?
 
   # <!--
   #   rdoc-file=string.c
@@ -367,7 +365,7 @@ class Symbol
   # -->
   # Equivalent to `sym.to_s.match?`; see String#match.
   #
-  def match?: (Regexp | string pattern, ?int pos) -> bool
+  def match?: (Regexp | string pattern, ?int offset) -> bool
 
   # <!-- rdoc-file=string.c -->
   # Equivalent to `self.to_s.succ.to_sym`:
@@ -378,6 +376,20 @@ class Symbol
   #
   def next: () -> Symbol
 
+  # <!--
+  #   rdoc-file=string.c
+  #   - name -> string
+  # -->
+  # Returns a frozen string representation of `self` (not including the leading
+  # colon):
+  #
+  #     :foo.name         # => "foo"
+  #     :foo.name.frozen? # => true
+  #
+  # Related: Symbol#to_s, Symbol#inspect.
+  #
+  def name: () -> String
+
   # <!-- rdoc-file=string.c -->
   # Equivalent to `self.to_s.length`; see String#length.
   #
@@ -394,7 +406,7 @@ class Symbol
   # -->
   # Equivalent to `self.to_s.start_with?`; see String#start_with?.
   #
-  def start_with?: (*string | Regexp prefixes) -> bool
+  def start_with?: (*Regexp | string prefixes) -> bool
 
   # <!--
   #   rdoc-file=string.c
@@ -445,7 +457,7 @@ class Symbol
   #
   # Related: Symbol#inspect, Symbol#name.
   #
-  alias to_s id2name
+  def to_s: () -> String
 
   # <!--
   #   rdoc-file=symbol.rb
@@ -455,7 +467,7 @@ class Symbol
   #
   # Related: String#to_sym.
   #
-  alias to_sym intern
+  def to_sym: () -> self
 
   # <!--
   #   rdoc-file=string.c
@@ -469,6 +481,4 @@ class Symbol
             | (:ascii | :lithuanian | :turkic) -> Symbol
             | (:lithuanian, :turkic) -> Symbol
             | (:turkic, :lithuanian) -> Symbol
-
-  def clone: (?freeze: true?) -> self
 end
diff --git a/test/stdlib/Symbol_test.rb b/test/stdlib/Symbol_test.rb
index bdfe378a0..4603dab1c 100644
--- a/test/stdlib/Symbol_test.rb
+++ b/test/stdlib/Symbol_test.rb
@@ -1,12 +1,12 @@
-require_relative "test_helper"
+require_relative 'test_helper'
 
 class SymbolSingletonTest < Test::Unit::TestCase
   include TestHelper
 
-  testing "singleton(::Symbol)"
+  testing 'singleton(::Symbol)'
 
   def test_all_symbols
-    assert_send_type "() -> Array[Symbol]",
+    assert_send_type '() -> Array[Symbol]',
                      Symbol, :all_symbols
   end
 end
@@ -14,33 +14,37 @@ def test_all_symbols
 class SymbolInstanceTest < Test::Unit::TestCase
   include TestHelper
 
-  testing "::Symbol"
+  testing '::Symbol'
 
-  def test_cmp
-    assert_send_type "(Symbol) -> Integer",
-                     :a, :<=>, :a
-    assert_send_type "(Integer) -> nil",
-                     :a, :<=>, 42
+  def test_op_cmp
+    %i[a b s y z].each do |other|
+      assert_send_type '(Symbol) -> (-1 | 0 |1)',
+                       :s, :<=>, other
+    end
+
+    with_untyped do |untyped|
+      next if Symbol === untyped
+
+      assert_send_type '(untyped) -> nil',
+                       :a, :<=>, untyped
+    end
   end
 
-  def test_eq
-    assert_send_type "(Symbol) -> true",
-                     :a, :==, :a
-    assert_send_type "(Integer) -> false",
-                     :a, :==, 42
+  def test_op_eq(method: :==)
+    with_untyped.and :a do |untyped|
+      assert_send_type '(untyped) -> bool',
+                       :a, method, untyped
+    end
   end
 
-  def test_eqq
-    assert_send_type "(Symbol) -> true",
-                     :a, :===, :a
-    assert_send_type "(Integer) -> false",
-                     :a, :===, 42
+  def test_op_eqq
+    test_op_eq(method: :===)
   end
 
-  def test_match_op
-    assert_send_type "(Regexp) -> Integer",
+  def test_op_match
+    assert_send_type '(Regexp) -> Integer',
                      :a, :=~, /a/
-    assert_send_type "(nil) -> nil",
+    assert_send_type '(nil) -> nil',
                      :a, :=~, nil
 
     matcher = BlankSlate.new
@@ -51,312 +55,282 @@ def matcher.=~(rhs)
                      :hello, :=~, matcher
   end
 
-  def test_aref
-    assert_send_type "(Integer) -> String",
-                     :a, :[], 0
-    assert_send_type "(ToInt) -> String",
-                     :a, :[], ToInt.new(0)
-    assert_send_type "(Integer) -> nil",
-                     :a, :[], 1
-    assert_send_type "(ToInt) -> nil",
-                     :a, :[], ToInt.new(1)
-    assert_send_type "(Integer, Integer) -> String",
-                     :a, :[], 0, 1
-    assert_send_type "(Integer, Integer) -> nil",
-                     :a, :[], 2, 1
-    assert_send_type "(ToInt, ToInt) -> String",
-                     :a, :[], ToInt.new(0), ToInt.new(1)
-    assert_send_type "(ToInt, ToInt) -> nil",
-                     :a, :[], ToInt.new(2), ToInt.new(1)
-    assert_send_type "(Range[Integer]) -> String",
-                     :a, :[], 0..1
-    assert_send_type "(Range[Integer]) -> nil",
-                     :a, :[], 2..1
-    assert_send_type "(Range[Integer?]) -> String",
-                     :a, :[], (0...)
-    assert_send_type "(Range[Integer?]) -> nil",
-                     :a, :[], (2...)
-    assert_send_type "(Range[Integer?]) -> String",
-                     :a, :[], (...0)
-    assert_send_type "(Regexp) -> String",
-                     :a, :[], /a/
-    assert_send_type "(Regexp) -> nil",
-                     :a, :[], /b/
-    assert_send_type "(Regexp, Integer) -> String",
-                     :a, :[], /a/, 0
-    assert_send_type "(Regexp, Integer) -> nil",
-                     :a, :[], /b/, 0
-    assert_send_type "(Regexp, ToInt) -> String",
-                     :a, :[], /a/, ToInt.new(0)
-    assert_send_type "(Regexp, ToInt) -> nil",
-                     :a, :[], /b/, ToInt.new(0)
-    assert_send_type "(Regexp, String) -> String",
-                     :a, :[], /(?<a>a)/, "a"
-    assert_send_type "(Regexp, String) -> nil",
-                     :a, :[], /(?<b>b)/, "b"
-    assert_send_type "(String) -> String",
-                     :a, :[], "a"
-    assert_send_type "(String) -> nil",
-                     :a, :[], "b"
+  def test_op_aref(method: :[])
+    # (int start, ?int length) -> String?
+    with_int(3) do |start|
+      assert_send_type  '(int) -> String',
+                        :'hello, world', method, start
+      assert_send_type  '(int) -> nil',
+                        :q, method, start
+
+      with_int 3 do |length|
+        assert_send_type  '(int, int) -> String',
+                          :'hello, world', method, start, length
+        assert_send_type  '(int, int) -> nil',
+                          :q, method, start, length
+      end
+    end
+
+    # (range[int?] range) -> String?
+    with_range with_int(3).and_nil, with_int(5).and_nil do |range|
+      assert_send_type  '(range[int?]) -> String',
+                        :hello, method, range
+
+      next if nil == range.begin # if the starting value is `nil`, you can't get `nil` outputs.
+      assert_send_type  '(range[int?]) -> nil',
+                        :hi, method, range
+    end
+
+    # (Regexp regexp, ?MatchData::capture backref) -> String?
+    assert_send_type  '(Regexp) -> String',
+                      :hello, method, /./
+    assert_send_type  '(Regexp) -> nil',
+                      :hello, method, /doesn't match/
+    with_int(1).and 'a', :a do |backref|
+      assert_send_type  '(Regexp, MatchData::capture) -> String',
+                        :hallo, method, /(?<a>)./, backref
+      assert_send_type  '(Regexp, MatchData::capture) -> nil',
+                        :hallo, method, /(?<a>)doesn't match/, backref
+    end
+
+    # (String substring) -> String?
+    assert_send_type  '(String) -> String',
+                      :hello, method, 'hello'
+    assert_send_type  '(String) -> nil',
+                      :hello, method, 'does not exist'
+    refute_send_type  '(_ToStr) -> untyped',
+                      :hello, method, ToStr.new('e')
   end
 
   def test_capitalize
-    assert_send_type "() -> Symbol",
+    assert_send_type '() -> Symbol',
                      :a, :capitalize
-    assert_send_type "(:ascii) -> Symbol",
+    assert_send_type '(:ascii) -> Symbol',
                      :a, :capitalize, :ascii
-    assert_send_type "(:lithuanian) -> Symbol",
+    assert_send_type '(:lithuanian) -> Symbol',
                      :a, :capitalize, :lithuanian
-    assert_send_type "(:turkic) -> Symbol",
+    assert_send_type '(:turkic) -> Symbol',
                      :a, :capitalize, :turkic
-    assert_send_type "(:lithuanian, :turkic) -> Symbol",
+    assert_send_type '(:lithuanian, :turkic) -> Symbol',
                      :a, :capitalize, :lithuanian, :turkic
-    assert_send_type "(:turkic, :lithuanian) -> Symbol",
+    assert_send_type '(:turkic, :lithuanian) -> Symbol',
                      :a, :capitalize, :turkic, :lithuanian
   end
 
   def test_casecmp
-    assert_send_type "(Symbol) -> 0",
-                     :a, :casecmp, :A
-    assert_send_type "(Symbol) -> -1",
-                     :a, :casecmp, :B
-    assert_send_type "(Symbol) -> 1",
-                     :b, :casecmp, :A
-    assert_send_type "(Symbol) -> nil",
-                     "\u{e4 f6 fc}".encode("ISO-8859-1").to_sym, :casecmp, :"\u{c4 d6 dc}"
-    assert_send_type "(Integer) -> nil",
-                     :a, :casecmp, 42
+    %i[a A s S z Z].each do |other|
+      assert_send_type '(Symbol) -> (-1 | 0 | 1)',
+                       :s, :casecmp, other
+    end
+
+    # invalid encoding
+    assert_send_type '(Symbol) -> nil',
+                     "\u{e4 f6 fc}".encode('ISO-8859-1').to_sym, :casecmp, :"\u{c4 d6 dc}"
+
+    with_untyped do |other|
+      next if Symbol === other
+
+      assert_send_type '(untyped) -> nil',
+                       :a, :casecmp, other
+    end
   end
 
-  def test_casecmp_p
-    assert_send_type "(Symbol) -> true",
-                     :a, :casecmp?, :A
-    assert_send_type "(Symbol) -> false",
-                     :a, :casecmp?, :B
-    assert_send_type "(Symbol) ->nil",
-                     "\u{e4 f6 fc}".encode("ISO-8859-1").to_sym, :casecmp?, :"\u{c4 d6 dc}"
-    assert_send_type "(Integer) -> nil",
-                     :a, :casecmp?, 42
+  def test_casecmp?
+    %i[a A s S z Z].each do |other|
+      assert_send_type '(Symbol) -> bool',
+                       :s, :casecmp?, other
+    end
+
+    # invalid encoding
+    assert_send_type '(Symbol) -> nil',
+                     '\u{e4 f6 fc}'.encode('ISO-8859-1').to_sym, :casecmp?, :'\u{c4 d6 dc}'
+
+    with_untyped do |other|
+      next if Symbol === other
+
+      assert_send_type '(untyped) -> nil',
+                       :a, :casecmp?, other
+    end
   end
 
   def test_downcase
-    assert_send_type "() -> Symbol",
+    assert_send_type '() -> Symbol',
                      :a, :downcase
-    assert_send_type "(:ascii) -> Symbol",
+    assert_send_type '(:ascii) -> Symbol',
                      :a, :downcase, :ascii
-    assert_send_type "(:fold) -> Symbol",
+    assert_send_type '(:fold) -> Symbol',
                      :a, :downcase, :fold
-    assert_send_type "(:lithuanian) -> Symbol",
+    assert_send_type '(:lithuanian) -> Symbol',
                      :a, :downcase, :lithuanian
-    assert_send_type "(:turkic) -> Symbol",
+    assert_send_type '(:turkic) -> Symbol',
                      :a, :downcase, :turkic
-    assert_send_type "(:lithuanian, :turkic) -> Symbol",
+    assert_send_type '(:lithuanian, :turkic) -> Symbol',
                      :a, :downcase, :lithuanian, :turkic
-    assert_send_type "(:turkic, :lithuanian) -> Symbol",
+    assert_send_type '(:turkic, :lithuanian) -> Symbol',
                      :a, :downcase, :turkic, :lithuanian
   end
 
   def test_empty_p
-    assert_send_type "() -> true",
-                     :"", :empty?
-    assert_send_type "() -> false",
+    assert_send_type '() -> bool',
                      :a, :empty?
   end
 
   def test_encoding
-    assert_send_type "() -> Encoding",
+    assert_send_type '() -> Encoding',
                      :a, :encoding
   end
 
   def test_end_with?
-    assert_send_type "() -> false",
+    assert_send_type '() -> bool',
                      :a, :end_with?
-    assert_send_type "(String) -> true",
-                     :a, :end_with?, "a"
-    assert_send_type "(String) -> false",
-                     :a, :end_with?, "b"
-    assert_send_type "(String, String) -> true",
-                     :a, :end_with?, "a", "b"
-    assert_send_type "(ToStr) -> true",
-                     :a, :end_with?, ToStr.new("a")
+    
+    with_string 'a' do |string_a|
+      assert_send_type '(string) -> true',
+                       :a, :end_with?, string_a
+
+      with_string 'b' do |string_b|
+        assert_send_type '(string, string) -> true',
+                         :a, :end_with?, string_a, string_b
+      end
+    end
   end
 
   def test_id2name
-    assert_send_type "() -> String",
-                     :a, :id2name
+    test_to_s(method: :id2name)
   end
 
   def test_inspect
-    assert_send_type "() -> String",
+    assert_send_type '() -> String',
                      :a, :inspect
   end
 
   def test_intern
-    assert_send_type "() -> Symbol",
-                     :a, :intern
+    test_to_sym(method: :intern)
   end
 
-  def test_length
-    assert_send_type "() -> Integer",
-                     :a, :length
+  def test_length(method: :length)
+    assert_send_type '() -> Integer',
+                     :a, method
   end
 
   def test_match
-    assert_send_type "(Regexp) -> MatchData",
-                     :a, :match, /a/
-    assert_send_type "(Regexp) -> nil",
-                     :a, :match, /b/
-    assert_send_type "(String) -> MatchData",
-                     :a, :match, "a"
-    assert_send_type "(String) -> nil",
-                     :a, :match, "b"
-    assert_send_type "(ToStr) -> MatchData",
-                     :a, :match, ToStr.new("a")
-    assert_send_type "(ToStr) -> nil",
-                     :a, :match, ToStr.new("b")
-    assert_send_type "(Regexp, Integer) -> MatchData",
-                     :a, :match, /a/, 0
-    assert_send_type "(Regexp, Integer) -> nil",
-                     :a, :match, /a/, 1
-    assert_send_type "(String, Integer) -> MatchData",
-                     :a, :match, "a", 0
-    assert_send_type "(String, Integer) -> nil",
-                     :a, :match, "a", 1
-    assert_send_type "(ToStr, Integer) -> MatchData",
-                     :a, :match, ToStr.new("a"), 0
-    assert_send_type "(ToStr, Integer) -> nil",
-                     :a, :match, ToStr.new("a"), 1
-    assert_send_type "(Regexp, ToInt) -> MatchData",
-                     :a, :match, /a/, ToInt.new(0)
-    assert_send_type "(Regexp, ToInt) -> nil",
-                     :a, :match, /a/, ToInt.new(1)
-    assert_send_type "(String, ToInt) -> MatchData",
-                     :a, :match, "a", ToInt.new(0)
-    assert_send_type "(String, ToInt) -> nil",
-                     :a, :match, "a", ToInt.new(1)
-    assert_send_type "(ToStr, ToInt) -> MatchData",
-                     :a, :match, ToStr.new("a"), ToInt.new(0)
-    assert_send_type "(ToStr, ToInt) -> nil",
-                     :a, :match, ToStr.new("a"), ToInt.new(1)
-    assert_send_type "(Regexp) { (MatchData) -> void } -> untyped",
-                     :a, :match, /a/ do |_m| end
+    with_string('l').and /l/ do |pattern|
+      assert_send_type  '(Regexp | string) -> MatchData',
+                        :hello, :match, pattern
+      assert_send_type  '(Regexp | string) -> nil',
+                        :heya, :match, pattern
+
+      assert_send_type  '[T] (Regexp | string) { (MatchData) -> T } -> T',
+                        :hello, :match, pattern do 1r end
+      assert_send_type  '[T] (Regexp | string) { (MatchData) -> T } -> nil',
+                        :heya, :match, pattern do 1r end
+
+      with_int 0 do |offset|
+        assert_send_type  '(Regexp | string, int) -> MatchData',
+                          :hello, :match, pattern, offset
+        assert_send_type  '(Regexp | string, int) -> nil',
+                          :heya, :match, pattern, offset
+
+        assert_send_type  '[T] (Regexp | string, int) { (MatchData) -> T } -> T',
+                          :hello, :match, pattern, offset do 1r end
+        assert_send_type  '[T] (Regexp | string, int) { (MatchData) -> T } -> nil',
+                          :heya, :match, pattern, offset do 1r end
+      end
+    end
   end
 
   def test_match?
-    assert_send_type "(Regexp) -> true",
-                     :a, :match?, /a/
-    assert_send_type "(Regexp) -> false",
-                     :a, :match?, /b/
-    assert_send_type "(String) -> true",
-                     :a, :match?, "a"
-    assert_send_type "(String) -> false",
-                     :a, :match?, "b"
-    assert_send_type "(ToStr) -> true",
-                     :a, :match?, ToStr.new("a")
-    assert_send_type "(ToStr) -> false",
-                     :a, :match?, ToStr.new("b")
-    assert_send_type "(Regexp, Integer) -> true",
-                     :a, :match?, /a/, 0
-    assert_send_type "(Regexp, Integer) -> false",
-                     :a, :match?, /a/, 1
-    assert_send_type "(String, Integer) -> true",
-                     :a, :match?, "a", 0
-    assert_send_type "(String, Integer) -> false",
-                     :a, :match?, "a", 1
-    assert_send_type "(ToStr, Integer) -> true",
-                     :a, :match?, ToStr.new("a"), 0
-    assert_send_type "(ToStr, Integer) -> false",
-                     :a, :match?, ToStr.new("a"), 1
-    assert_send_type "(Regexp, ToInt) -> true",
-                     :a, :match?, /a/, ToInt.new(0)
-    assert_send_type "(Regexp, ToInt) -> false",
-                     :a, :match?, /a/, ToInt.new(1)
-    assert_send_type "(String, ToInt) -> true",
-                     :a, :match?, "a", ToInt.new(0)
-    assert_send_type "(String, ToInt) -> false",
-                     :a, :match?, "a", ToInt.new(1)
-    assert_send_type "(ToStr, ToInt) -> true",
-                     :a, :match?, ToStr.new("a"), ToInt.new(0)
-    assert_send_type "(ToStr, ToInt) -> false",
-                     :a, :match?, ToStr.new("a"), ToInt.new(1)
+    with_string('l').and /l/ do |pattern|
+      assert_send_type  '(Regexp | string) -> bool',
+                        :hello, :match?, pattern
+      assert_send_type  '(Regexp | string) -> bool',
+                        :heya, :match?, pattern
+
+      with_int 0 do |offset|
+        assert_send_type  '(Regexp | string, int) -> bool',
+                          :hello, :match?, pattern, offset
+        assert_send_type  '(Regexp | string, int) -> bool',
+                          :heya, :match?, pattern, offset
+      end
+    end
+  end
+
+  def test_next(method: :next)
+    assert_send_type '() -> Symbol',
+                     :a, method
   end
 
-  def test_next
-    assert_send_type "() -> Symbol",
-                     :a, :next
+  def test_name
+    assert_send_type '() -> String',
+                     :a, :name
   end
 
   def test_size
-    assert_send_type "() -> Integer",
-                     :a, :size
+    test_length(method: :size)
+  end
+
+  def test_slice
+    test_op_aref(method: :slice)
   end
 
   def test_start_with?
-    assert_send_type "() -> false",
-                     :a, :start_with?
-    assert_send_type "(String) -> true",
-                     :a, :start_with?, "a"
-    assert_send_type "(String) -> false",
-                     :a, :start_with?, "b"
-    assert_send_type "(String, String) -> true",
-                     :a, :start_with?, "b", "a"
-    assert_send_type "(ToStr) -> true",
-                     :a, :start_with?, ToStr.new("a")
-    assert_send_type "(ToStr) -> false",
-                     :a, :start_with?, ToStr.new("b")
-    assert_send_type "(ToStr, ToStr) -> true",
-                     :a, :start_with?, ToStr.new("b"), ToStr.new("a")
-    assert_send_type "(Regexp) -> true",
-                     :a, :start_with?, /a/
+    assert_send_type  '() -> bool',
+                      :hello, :start_with?
+
+    with_string('he').and /he/ do |prefix|
+      assert_send_type  '(*string | Regexp) -> bool',
+                        :hello, :start_with?, prefix
+      assert_send_type  '(*string | Regexp) -> bool',
+                        :hello, :start_with?, prefix, prefix
+    end
   end
 
   def test_succ
-    assert_send_type "() -> Symbol",
-                     :a, :succ
+    test_next(method: :succ)
   end
 
   def test_swapcase
-    assert_send_type "() -> Symbol",
+    assert_send_type '() -> Symbol',
                      :a, :swapcase
-    assert_send_type "(:ascii) -> Symbol",
+    assert_send_type '(:ascii) -> Symbol',
                      :a, :swapcase, :ascii
-    assert_send_type "(:lithuanian) -> Symbol",
+    assert_send_type '(:lithuanian) -> Symbol',
                      :a, :swapcase, :lithuanian
-    assert_send_type "(:turkic) -> Symbol",
+    assert_send_type '(:turkic) -> Symbol',
                      :a, :swapcase, :turkic
-    assert_send_type "(:lithuanian, :turkic) -> Symbol",
+    assert_send_type '(:lithuanian, :turkic) -> Symbol',
                      :a, :swapcase, :lithuanian, :turkic
-    assert_send_type "(:turkic, :lithuanian) -> Symbol",
+    assert_send_type '(:turkic, :lithuanian) -> Symbol',
                      :a, :swapcase, :turkic, :lithuanian
   end
 
   def test_to_proc
-    assert_send_type "() -> Proc",
+    assert_send_type '() -> Proc',
                      :a, :to_proc
   end
 
-  def test_to_s
-    assert_send_type "() -> String",
-                     :a, :to_s
+  def test_to_s(method: :to_s)
+    assert_send_type '() -> String',
+                     :a, method
   end
 
-  def test_to_sym
-    assert_send_type "() -> Symbol",
-                     :a, :to_sym
+  def test_to_sym(method: :to_sym)
+    assert_send_type '() -> Symbol',
+                     :a, method
   end
 
   def test_upcase
-    assert_send_type "() -> Symbol",
+    assert_send_type '() -> Symbol',
                      :a, :upcase
-    assert_send_type "(:ascii) -> Symbol",
+    assert_send_type '(:ascii) -> Symbol',
                      :a, :upcase, :ascii
-    assert_send_type "(:lithuanian) -> Symbol",
+    assert_send_type '(:lithuanian) -> Symbol',
                      :a, :upcase, :lithuanian
-    assert_send_type "(:turkic) -> Symbol",
+    assert_send_type '(:turkic) -> Symbol',
                      :a, :upcase, :turkic
-    assert_send_type "(:lithuanian, :turkic) -> Symbol",
+    assert_send_type '(:lithuanian, :turkic) -> Symbol',
                      :a, :upcase, :lithuanian, :turkic
-    assert_send_type "(:turkic, :lithuanian) -> Symbol",
+    assert_send_type '(:turkic, :lithuanian) -> Symbol',
                      :a, :upcase, :turkic, :lithuanian
   end
 end