From e194c86243ce0ff91809bdc090d5f8789b947e28 Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 09:46:54 -0700
Subject: [PATCH 1/6] first commit, remove old unit tests

---
 test/stdlib/Float_test.rb | 195 ++------------------------------------
 1 file changed, 6 insertions(+), 189 deletions(-)

diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index 4981ac9e2f..4eaf2d4e68 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -1,196 +1,13 @@
-require_relative "test_helper"
+require_relative 'test_helper'
 
-class FloatTest < StdlibTest
-  target Float
-
-  def test_calc
-    10.0 % 3
-    10.0 % 3.1
-    10.0 % 3r
-
-    3.0 * 1
-    3.0 * 1.1
-    3.0 * Complex.rect(1,2)
-    3.0 * 2r
-
-    3.1 ** 2
-    3.1 ** 1.2
-    3.1 ** Complex.rect(1,2)
-    3.1 ** 2r
-
-    3.0 + 1
-    3.0 + 1.1
-    3.0 + 2r
-    3.0 + Complex.rect(1,2)
-
-    3.0 - 1
-    3.0 - 1.1
-    3.0 - 2r
-    3.0 - Complex.rect(1,2)
-
-    3.0 / 1
-    3.0 / 1.1
-    3.0 / 2r
-    3.0 / Complex.rect(1,2)
-  end
-
-  def test_compare
-    1.0 <=> 1
-    1.0 < 1
-    1.0 <= 3r
-    1.0 > 3.1
-  end
-
-  def test_eq
-    a = 1.0
-
-    a == 1
-    a == Object.new
-
-    a === 1
-    a === Object.new
-  end
-
-  def test_abs
-    a = 3.1
-
-    a.abs
-    a.abs2
-  end
-
-  def test_angle
-    a = 3.1
-
-    a.angle
-    a.arg
-    -a.phase
-  end
-
-  def test_ceil
-    a = 31.2
-
-    a.ceil
-    a.ceil(3)
-    a.ceil(ToInt.new)
-  end
-
-  def test_coerce
-    1.2.coerce(3)
-    2.5.coerce(1.1)
-  end
-
-  def test_denominator
-    a = 13.3
-
-    a.denominator
-  end
-
-  def test_div
-    a = 12.3
-
-    a.div(3)
-    a.div(3.1)
-    a.div(12r)
-
-    a.divmod(3)
-    a.divmod(3.1)
-    a.divmod(1r/5)
-  end
-
-  def test_fdiv
-    a = 3.2
-
-    a.fdiv(3)
-    a.fdiv(3.1)
-    a.fdiv(1r/3)
-    a.fdiv(Complex.rect(1,2))
-  end
-
-  def test_floor
-    a = 3.2
-
-    a.floor()
-    a.floor(-1)
-    a.floor(ToInt.new) # No to_int support
-  end
-
-  def test_modulo
-    a = 3.2
-
-    a.modulo(2)
-    a.modulo(1.1)
-    a.modulo(a)
-  end
-
-  def test_numerator
-    a = 3.2
-
-    a.numerator
-  end
-
-  def test_polar
-    3.1.polar
-    (-3.12).polar
-  end
-
-  def test_quo
-    a = 1.11
-
-    a.quo(3)
-    a.quo(1.3)
-    a.quo(1r/3)
-    a.quo(Complex.rect(1,2))
-  end
-
-  def test_rationalize
-    a = 1.22232.next_float
-
-    a.rationalize
-    a.rationalize(3.11)
-  end
-
-  def test_reminder
-    a = 1.4
-
-    a.remainder(3)
-    a.remainder(3.1)
-    a.remainder(3r/5)
-  end
-
-  def test_round
-    a = 1.3
-
-    a.round(half: :up)
-    a.round(2, half: :up)
-    a.round(ToInt.new(-2), half: :up)
-  end
-
-  def test_step
-    a = 1.3
-
-    a.step { break }
-    a.step(1, 2) { }
-    a.step(by: 3, to: 100) { }
-  end
-
-  def test_to_s
-    a = 1.3
-
-    a.to_s
-  end
-
-  def test_truncate
-    a = 1.3
+class FloatSingletonTest < Test::Unit::TestCase
+  include TestHelper
 
-    a.truncate
-    a.truncate(1)
-  end
+  testing 'singleton(Float)'
 end
 
-class FloatConstantTest < Test::Unit::TestCase
+class FloatInstanceTest < Test::Unit::TestCase
   include TestHelper
 
-  def test_constant
-    assert_const_type "Float", "Float::INFINITY"
-  end
+  testing 'Float'
 end

From c40dbb00ded1edc18aa82c2814525fe2fa6d4088 Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 09:55:03 -0700
Subject: [PATCH 2/6] added constants in

---
 core/float.rbs            | 230 +++++++++++++++++++-------------------
 test/stdlib/Float_test.rb |  66 +++++++++++
 2 files changed, 182 insertions(+), 114 deletions(-)

diff --git a/core/float.rbs b/core/float.rbs
index d5d00a50a6..f3fa7f9644 100644
--- a/core/float.rbs
+++ b/core/float.rbs
@@ -253,6 +253,122 @@
 # *   #truncate: Returns `self` truncated to a given precision.
 #
 class Float < Numeric
+  # <!-- rdoc-file=numeric.c -->
+  # The minimum number of significant decimal digits in a double-precision
+  # floating point.
+  #
+  # Usually defaults to 15.
+  #
+  DIG: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # The difference between 1 and the smallest double-precision floating point
+  # number greater than 1.
+  #
+  # Usually defaults to 2.2204460492503131e-16.
+  #
+  EPSILON: Float
+
+  # <!-- rdoc-file=numeric.c -->
+  # An expression representing positive infinity.
+  #
+  INFINITY: Float
+
+  %a{deprecated:Does not actually exist}
+  Infinity: Float
+
+  # <!-- rdoc-file=numeric.c -->
+  # The number of base digits for the `double` data type.
+  #
+  # Usually defaults to 53.
+  #
+  MANT_DIG: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # The largest possible integer in a double-precision floating point number.
+  #
+  # Usually defaults to 1.7976931348623157e+308.
+  #
+  MAX: Float
+
+  # <!-- rdoc-file=numeric.c -->
+  # The largest positive exponent in a double-precision floating point where 10
+  # raised to this power minus 1.
+  #
+  # Usually defaults to 308.
+  #
+  MAX_10_EXP: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # The largest possible exponent value in a double-precision floating point.
+  #
+  # Usually defaults to 1024.
+  #
+  MAX_EXP: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # The smallest positive normalized number in a double-precision floating point.
+  #
+  # Usually defaults to 2.2250738585072014e-308.
+  #
+  # If the platform supports denormalized numbers, there are numbers between zero
+  # and Float::MIN. <code>0.0.next_float</code> returns the smallest positive
+  # floating point number including denormalized numbers.
+  #
+  MIN: Float
+
+  # <!-- rdoc-file=numeric.c -->
+  # The smallest negative exponent in a double-precision floating point where 10
+  # raised to this power minus 1.
+  #
+  # Usually defaults to -307.
+  #
+  MIN_10_EXP: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # The smallest possible exponent value in a double-precision floating point.
+  #
+  # Usually defaults to -1021.
+  #
+  MIN_EXP: Integer
+
+  # <!-- rdoc-file=numeric.c -->
+  # An expression representing a value which is "not a number".
+  #
+  NAN: Float
+
+  # <!-- rdoc-file=numeric.c -->
+  # The base of the floating point, or number of unique digits used to represent
+  # the number.
+  #
+  # Usually defaults to 2 on most systems, which would represent a base-10
+  # decimal.
+  #
+  RADIX: Integer
+
+  # Deprecated, do not use.
+  #
+  # Represents the rounding mode for floating point addition at the start time.
+  #
+  # Usually defaults to 1, rounding to the nearest number.
+  #
+  # Other modes include:
+  #
+  # -1
+  # :   Indeterminable
+  # 0
+  # :   Rounding towards zero
+  # 1
+  # :   Rounding to the nearest number
+  # 2
+  # :   Rounding towards positive infinity
+  # 3
+  # :   Rounding towards negative infinity
+  #
+  #
+  %a{deprecated}
+  ROUNDS: Integer
+
   # <!--
   #   rdoc-file=numeric.c
   #   - self % other -> float
@@ -1200,117 +1316,3 @@ class Float < Numeric
   #
   def zero?: () -> bool
 end
-
-# <!-- rdoc-file=numeric.c -->
-# The minimum number of significant decimal digits in a double-precision
-# floating point.
-#
-# Usually defaults to 15.
-#
-Float::DIG: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# The difference between 1 and the smallest double-precision floating point
-# number greater than 1.
-#
-# Usually defaults to 2.2204460492503131e-16.
-#
-Float::EPSILON: Float
-
-# <!-- rdoc-file=numeric.c -->
-# An expression representing positive infinity.
-#
-Float::INFINITY: Float
-
-Float::Infinity: Float
-
-# <!-- rdoc-file=numeric.c -->
-# The number of base digits for the `double` data type.
-#
-# Usually defaults to 53.
-#
-Float::MANT_DIG: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# The largest possible integer in a double-precision floating point number.
-#
-# Usually defaults to 1.7976931348623157e+308.
-#
-Float::MAX: Float
-
-# <!-- rdoc-file=numeric.c -->
-# The largest positive exponent in a double-precision floating point where 10
-# raised to this power minus 1.
-#
-# Usually defaults to 308.
-#
-Float::MAX_10_EXP: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# The largest possible exponent value in a double-precision floating point.
-#
-# Usually defaults to 1024.
-#
-Float::MAX_EXP: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# The smallest positive normalized number in a double-precision floating point.
-#
-# Usually defaults to 2.2250738585072014e-308.
-#
-# If the platform supports denormalized numbers, there are numbers between zero
-# and Float::MIN. <code>0.0.next_float</code> returns the smallest positive
-# floating point number including denormalized numbers.
-#
-Float::MIN: Float
-
-# <!-- rdoc-file=numeric.c -->
-# The smallest negative exponent in a double-precision floating point where 10
-# raised to this power minus 1.
-#
-# Usually defaults to -307.
-#
-Float::MIN_10_EXP: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# The smallest possible exponent value in a double-precision floating point.
-#
-# Usually defaults to -1021.
-#
-Float::MIN_EXP: Integer
-
-# <!-- rdoc-file=numeric.c -->
-# An expression representing a value which is "not a number".
-#
-Float::NAN: Float
-
-# <!-- rdoc-file=numeric.c -->
-# The base of the floating point, or number of unique digits used to represent
-# the number.
-#
-# Usually defaults to 2 on most systems, which would represent a base-10
-# decimal.
-#
-Float::RADIX: Integer
-
-# Deprecated, do not use.
-#
-# Represents the rounding mode for floating point addition at the start time.
-#
-# Usually defaults to 1, rounding to the nearest number.
-#
-# Other modes include:
-#
-# -1
-# :   Indeterminable
-# 0
-# :   Rounding towards zero
-# 1
-# :   Rounding to the nearest number
-# 2
-# :   Rounding towards positive infinity
-# 3
-# :   Rounding towards negative infinity
-#
-#
-Float::ROUNDS: Integer
diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index 4eaf2d4e68..52f862eaf9 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -4,6 +4,72 @@ class FloatSingletonTest < Test::Unit::TestCase
   include TestHelper
 
   testing 'singleton(Float)'
+
+  def test_constant_DIG
+    assert_const_type 'Integer',
+                      'Float::DIG'
+  end
+
+  def test_constant_EPSILON
+    assert_const_type 'Float',
+                      'Float::EPSILON'
+  end
+
+  def test_constant_INFINITY
+    assert_const_type 'Float',
+                      'Float::INFINITY'
+  end
+
+  def test_constant_MANT_DIG
+    assert_const_type 'Integer',
+                      'Float::MANT_DIG'
+  end
+
+  def test_constant_MAX
+    assert_const_type 'Float',
+                      'Float::MAX'
+  end
+
+  def test_constant_MAX_10_EXP
+    assert_const_type 'Integer',
+                      'Float::MAX_10_EXP'
+  end
+
+  def test_constant_MAX_EXP
+    assert_const_type 'Integer',
+                      'Float::MAX_EXP'
+  end
+
+  def test_constant_MIN
+    assert_const_type 'Float',
+                      'Float::MIN'
+  end
+
+  def test_constant_MIN_10_EXP
+    assert_const_type 'Integer',
+                      'Float::MIN_10_EXP'
+  end
+
+  def test_constant_MIN_EXP
+    assert_const_type 'Integer',
+                      'Float::MIN_EXP'
+  end
+
+  def test_constant_NAN
+    assert_const_type 'Float',
+                      'Float::NAN'
+  end
+
+  def test_constant_RADIX
+    assert_const_type 'Integer',
+                      'Float::RADIX'
+  end
+
+  def test_constant_ROUNDS
+    notify "Skipping test: Float::ROUNDS does not exist" unless defined? Float::ROUNDS
+    assert_const_type 'Integer',
+                      'Float::ROUNDS'
+  end
 end
 
 class FloatInstanceTest < Test::Unit::TestCase

From c1a53542311c2a7083956ab1ee6cb16ece4f756c Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 09:57:48 -0700
Subject: [PATCH 3/6] added instance method shell

---
 test/stdlib/Float_test.rb | 190 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 189 insertions(+), 1 deletion(-)

diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index 52f862eaf9..fde2bfeef0 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -66,7 +66,7 @@ def test_constant_RADIX
   end
 
   def test_constant_ROUNDS
-    notify "Skipping test: Float::ROUNDS does not exist" unless defined? Float::ROUNDS
+    return unless defined? Float::ROUNDS
     assert_const_type 'Integer',
                       'Float::ROUNDS'
   end
@@ -76,4 +76,192 @@ class FloatInstanceTest < Test::Unit::TestCase
   include TestHelper
 
   testing 'Float'
+
+  def test_op_mod
+    omit 'todo'
+  end
+
+  def test_op_mul
+    omit 'todo'
+  end
+
+  def test_op_pow
+    omit 'todo'
+  end
+
+  def test_op_add
+    omit 'todo'
+  end
+
+  def test_op_sub
+    omit 'todo'
+  end
+
+  def test_op_uneg
+    omit 'todo'
+  end
+
+  def test_op_div
+    omit 'todo'
+  end
+
+  def test_op_lth
+    omit 'todo'
+  end
+
+  def test_op_leq
+    omit 'todo'
+  end
+
+  def test_op_cmp
+    omit 'todo'
+  end
+
+  def test_op_eq
+    omit 'todo'
+  end
+
+  def test_op_eqq
+    omit 'todo'
+  end
+
+  def test_op_gth
+    omit 'todo'
+  end
+
+  def test_op_geq
+    omit 'todo'
+  end
+
+  def test_abs
+    omit 'todo'
+  end
+
+  def test_angle
+    omit 'todo'
+  end
+
+  def test_arg
+    omit 'todo'
+  end
+
+  def test_ceil
+    omit 'todo'
+  end
+
+  def test_coerce
+    omit 'todo'
+  end
+
+  def test_denominator
+    omit 'todo'
+  end
+
+  def test_divmod
+    omit 'todo'
+  end
+
+  def test_eql?
+    omit 'todo'
+  end
+
+  def test_fdiv
+    omit 'todo'
+  end
+
+  def test_finite?
+    omit 'todo'
+  end
+
+  def test_floor
+    omit 'todo'
+  end
+
+  def test_hash
+    omit 'todo'
+  end
+
+  def test_infinite?
+    omit 'todo'
+  end
+
+  def test_inspect
+    omit 'todo'
+  end
+
+  def test_magnitude
+    omit 'todo'
+  end
+
+  def test_modulo
+    omit 'todo'
+  end
+
+  def test_nan?
+    omit 'todo'
+  end
+
+  def test_negative?
+    omit 'todo'
+  end
+
+  def test_next_float
+    omit 'todo'
+  end
+
+  def test_numerator
+    omit 'todo'
+  end
+
+  def test_phase
+    omit 'todo'
+  end
+
+  def test_positive?
+    omit 'todo'
+  end
+
+  def test_prev_float
+    omit 'todo'
+  end
+
+  def test_quo
+    omit 'todo'
+  end
+
+  def test_rationalize
+    omit 'todo'
+  end
+
+  def test_round
+    omit 'todo'
+  end
+
+  def test_to_f
+    omit 'todo'
+  end
+
+  def test_to_i
+    omit 'todo'
+  end
+
+  def test_to_int
+    omit 'todo'
+  end
+
+  def test_to_r
+    omit 'todo'
+  end
+
+  def test_to_s
+    omit 'todo'
+  end
+
+  def test_truncate
+    omit 'todo'
+  end
+
+  def test_zero?
+    omit 'todo'
+  end
 end

From 4e15c0e7dcfde3f728a4b594757f0045be622378 Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 10:13:00 -0700
Subject: [PATCH 4/6] first stage of singleton methods

---
 core/float.rbs            |  17 +++--
 test/stdlib/Float_test.rb | 128 +++++++++++++++++++++++++++++---------
 2 files changed, 107 insertions(+), 38 deletions(-)

diff --git a/core/float.rbs b/core/float.rbs
index f3fa7f9644..db219b9402 100644
--- a/core/float.rbs
+++ b/core/float.rbs
@@ -576,7 +576,7 @@ class Float < Numeric
   #
   # Related: Float#eql? (requires `other` to be a Float).
   #
-  def ==: (untyped) -> bool
+  def ==: (untyped other) -> bool
 
   # <!-- rdoc-file=numeric.c -->
   # Returns `true` if `other` has the same value as `self`, `false` otherwise:
@@ -591,7 +591,7 @@ class Float < Numeric
   #
   # Related: Float#eql? (requires `other` to be a Float).
   #
-  def ===: (untyped) -> bool
+  alias === ==
 
   # <!--
   #   rdoc-file=numeric.c
@@ -727,7 +727,7 @@ class Float < Numeric
   #
   # Raises an exception if a type conversion fails.
   #
-  def coerce: (Numeric) -> [ Float, Float ]
+  def coerce: (_ToF) -> [ Float, self ]
 
   # <!--
   #   rdoc-file=rational.c
@@ -784,7 +784,7 @@ class Float < Numeric
   #
   # Related: Float#== (performs type conversions).
   #
-  def eql?: (untyped) -> bool
+  def eql?: (untyped other) -> bool
 
   # <!-- rdoc-file=numeric.c -->
   # Returns the quotient from dividing `self` by `other`:
@@ -795,8 +795,7 @@ class Float < Numeric
   #     f.quo(Rational(2, 1)) # => 1.57
   #     f.quo(Complex(2, 0))  # => (1.57+0.0i)
   #
-  def fdiv: (Complex) -> Complex
-          | (Numeric) -> Float
+  alias fdiv quo
 
   # <!--
   #   rdoc-file=numeric.c
@@ -910,7 +909,7 @@ class Float < Numeric
   #     f = 0.0/0.0  # => NaN
   #     f.infinite?  # => nil
   #
-  def infinite?: () -> Integer?
+  def infinite?: () -> (-1 | 1)?
 
   # <!-- rdoc-file=numeric.c -->
   # Returns a string containing a representation of `self`; depending of the value
@@ -964,7 +963,7 @@ class Float < Numeric
   #     10.0 % 4.0            # => 2.0
   #     10.0 % Rational(4, 1) # => 2.0
   #
-  def modulo: (Numeric) -> Float
+  alias modulo %
 
   # <!--
   #   rdoc-file=numeric.c
@@ -1194,7 +1193,7 @@ class Float < Numeric
   # -->
   # Returns `self` (which is already a Float).
   #
-  def to_f: () -> Float
+  def to_f: () -> self
 
   # <!--
   #   rdoc-file=numeric.c
diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index fde2bfeef0..6d23b95808 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -77,7 +77,19 @@ class FloatInstanceTest < Test::Unit::TestCase
 
   testing 'Float'
 
-  def test_op_mod
+  def with_floats(infinity: true, nan: true)
+    yield 0.0
+    yield -0.0
+    yield 12.34
+    yield -38e99
+    yield Float::MIN
+    yield Float::MAX
+    yield Float::INFINITY if infinity
+    yield -Float::INFINITY if infinity
+    yield Float::NAN if nan
+  end
+
+  def test_op_mod(method: :%)
     omit 'todo'
   end
 
@@ -98,7 +110,10 @@ def test_op_sub
   end
 
   def test_op_uneg
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Float',
+                        float, :-@
+    end
   end
 
   def test_op_div
@@ -117,12 +132,18 @@ def test_op_cmp
     omit 'todo'
   end
 
-  def test_op_eq
-    omit 'todo'
+  def test_op_eq(method: :==)
+    with_floats do |float|
+      with_untyped.and float do |other|
+        next unless defined? other.==
+        assert_send_type  '(untyped) -> bool',
+                          float, method, other
+      end
+    end
   end
 
   def test_op_eqq
-    omit 'todo'
+    test_op_eq(method: :===)
   end
 
   def test_op_gth
@@ -133,8 +154,11 @@ def test_op_geq
     omit 'todo'
   end
 
-  def test_abs
-    omit 'todo'
+  def test_abs(method: :abs)
+    with_floats do |float|
+      assert_send_type  '() -> Float',
+                        float, method
+    end
   end
 
   def test_angle
@@ -150,7 +174,12 @@ def test_ceil
   end
 
   def test_coerce
-    omit 'todo'
+    with_floats do |float|
+      with_float do |other|
+        assert_send_type  '(_ToF) -> [Float, Float]',
+                          float, :coerce, other
+      end
+    end
   end
 
   def test_denominator
@@ -162,15 +191,23 @@ def test_divmod
   end
 
   def test_eql?
-    omit 'todo'
+    with_floats do |float|
+      with_untyped.and float do |other|
+        assert_send_type  '(untyped) -> bool',
+                          float, :eql?, other
+      end
+    end
   end
 
   def test_fdiv
-    omit 'todo'
+    test_quo(method: :fdiv)
   end
 
   def test_finite?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> bool',
+                        float, :finite?
+    end
   end
 
   def test_floor
@@ -178,35 +215,50 @@ def test_floor
   end
 
   def test_hash
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Integer',
+                        float, :hash
+    end
   end
 
   def test_infinite?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> (-1 | 1)?',
+                        float, :infinite?
+    end
   end
 
   def test_inspect
-    omit 'todo'
+    test_to_s(method: :inspect)
   end
 
   def test_magnitude
-    omit 'todo'
+    test_abs(method: :magnitude)
   end
 
   def test_modulo
-    omit 'todo'
+    test_op_mod(method: :modulo)
   end
 
   def test_nan?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> bool',
+                        float, :nan?
+    end
   end
 
   def test_negative?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> bool',
+                        float, :negative?
+    end
   end
 
   def test_next_float
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Float',
+                        float, :next_float
+    end
   end
 
   def test_numerator
@@ -218,14 +270,20 @@ def test_phase
   end
 
   def test_positive?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> bool',
+                        float, :positive?
+    end
   end
 
   def test_prev_float
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Float',
+                        float, :next_float
+    end
   end
 
-  def test_quo
+  def test_quo(method: :quo)
     omit 'todo'
   end
 
@@ -238,23 +296,32 @@ def test_round
   end
 
   def test_to_f
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Float',
+                        float, :to_f
+    end
   end
 
-  def test_to_i
-    omit 'todo'
+  def test_to_i(method: :to_i)
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Integer',
+                        float, method
+    end
   end
 
   def test_to_int
-    omit 'todo'
+    test_to_i(method: :to_int)
   end
 
   def test_to_r
     omit 'todo'
   end
 
-  def test_to_s
-    omit 'todo'
+  def test_to_s(method: :to_s)
+    with_floats do |float|
+      assert_send_type  '() -> String',
+                        float, method
+    end
   end
 
   def test_truncate
@@ -262,6 +329,9 @@ def test_truncate
   end
 
   def test_zero?
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> bool',
+                        float, :zero?
+    end
   end
 end

From 7e5a705ebe4a3e67d8244864e29c6557fc2762d8 Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 14:02:46 -0700
Subject: [PATCH 5/6] almost all done

---
 core/float.rbs             |  71 ++++++-----
 core/numeric.rbs           |   8 ++
 test/stdlib/Float_test.rb  | 251 +++++++++++++++++++++++++++++++++----
 test/stdlib/test_helper.rb |  37 ++++++
 4 files changed, 312 insertions(+), 55 deletions(-)

diff --git a/core/float.rbs b/core/float.rbs
index db219b9402..28c54b3fd7 100644
--- a/core/float.rbs
+++ b/core/float.rbs
@@ -396,10 +396,8 @@ class Float < Numeric
   #     10.0 % 4.0            # => 2.0
   #     10.0 % Rational(4, 1) # => 2.0
   #
-  def %: (Integer) -> Float
-       | (Float) -> Float
-       | (Rational) -> Float
-       | (Numeric) -> Numeric
+  def %: (Integer | Float other) -> Float
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Modulo[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -413,8 +411,8 @@ class Float < Numeric
   #     f * Rational(1, 2) # => 1.57
   #     f * Complex(2, 0)  # => (6.28+0.0i)
   #
-  def *: (Complex) -> Complex
-       | (Numeric) -> Float
+  def *: (Integer | Float other) -> Float
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Times[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -429,8 +427,9 @@ class Float < Numeric
   #     f ** Rational(2, 1) # => 9.8596
   #     f ** Complex(2, 0)  # => (9.8596+0i)
   #
-  def **: (Complex) -> Complex
-        | (Numeric) -> Float
+  def **: (Integer other) -> Float
+        | (Float other) -> (Float | Complex)
+        | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Power[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -449,8 +448,8 @@ class Float < Numeric
   #     3.14 + Complex(1, 0)   # => (4.140000000000001+0i)
   #     3.14 + Rational(1, 1)  # => 4.140000000000001
   #
-  def +: (Complex) -> Complex
-       | (Numeric) -> Float
+  def +: (Integer | Float other) -> Float
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Add[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -464,8 +463,8 @@ class Float < Numeric
   #     f - Rational(1, 1)    # => 2.14
   #     f - Complex(1, 0)     # => (2.14+0i)
   #
-  def -: (Complex) -> Complex
-       | (Numeric) -> Float
+  def -: (Integer | Float other) -> Float
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Subtract[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.rb
@@ -491,8 +490,8 @@ class Float < Numeric
   #     f / Rational(2, 1) # => 1.57
   #     f / Complex(2, 0)  # => (1.57+0.0i)
   #
-  def /: (Complex) -> Complex
-       | (Numeric) -> Float
+  def /: (Integer | Float other) -> Float
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Divide[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -509,7 +508,8 @@ class Float < Numeric
   # <code>Float::NAN < Float::NAN</code> returns an implementation-dependent
   # value.
   #
-  def <: (Numeric) -> bool
+  def <: (Integer | Float other) -> bool
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_LessThan[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -527,7 +527,8 @@ class Float < Numeric
   # <code>Float::NAN <= Float::NAN</code> returns an implementation-dependent
   # value.
   #
-  def <=: (Numeric) -> bool
+  def <=: (Integer | Float other) -> bool
+        | [S, R] (Numeric::_Coerce[self, RBS::Ops::_LessThanOrEqual[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -558,7 +559,8 @@ class Float < Numeric
   # Class Float includes module Comparable, each of whose methods uses Float#<=>
   # for comparison.
   #
-  def <=>: (Numeric) -> Integer?
+  def <=>: (Float other) -> (-1 | 0 | 1)?
+         | (untyped other) -> Integer?
 
   # <!--
   #   rdoc-file=numeric.c
@@ -607,7 +609,8 @@ class Float < Numeric
   # <code>Float::NAN > Float::NAN</code> returns an implementation-dependent
   # value.
   #
-  def >: (Numeric) -> bool
+  def >: (Integer | Float other) -> bool
+       | [S, R] (Numeric::_Coerce[self, RBS::Ops::_GreaterThan[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.c
@@ -624,7 +627,8 @@ class Float < Numeric
   # <code>Float::NAN >= Float::NAN</code> returns an implementation-dependent
   # value.
   #
-  def >=: (Numeric) -> bool
+  def >=: (Integer | Float other) -> bool
+        | [S, R] (Numeric::_Coerce[self, RBS::Ops::_GreaterThanOrEqual[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=numeric.rb
@@ -641,7 +645,7 @@ class Float < Numeric
   # <!-- rdoc-file=complex.c -->
   # Returns 0 if `self` is positive, Math::PI otherwise.
   #
-  def angle: ...
+  alias angle arg
 
   # <!--
   #   rdoc-file=complex.c
@@ -649,7 +653,7 @@ class Float < Numeric
   # -->
   # Returns 0 if `self` is positive, Math::PI otherwise.
   #
-  alias arg angle
+  def arg: () -> (0 | Float) # NB: Can also return `NaN` if self is NaN
 
   # <!--
   #   rdoc-file=numeric.c
@@ -711,7 +715,7 @@ class Float < Numeric
   # Related: Float#floor.
   #
   def ceil: () -> Integer
-          | (int digits) -> (Integer | Float)
+          | (int ndigits) -> (Integer | Float)
 
   # <!--
   #   rdoc-file=numeric.c
@@ -763,8 +767,13 @@ class Float < Numeric
   #     13.0.divmod(4.0)            # => [3, 1.0]
   #     13.0.divmod(Rational(4, 1)) # => [3, 1.0]
   #
-  def divmod: (Integer | Float | Rational) -> [ Integer, Float ]
-            | (Numeric) -> [ Numeric, Numeric ]
+  def divmod: (Integer | Float other) -> [ Integer, Float ]
+            | [S, R] (Numeric::_Coerce[self, _DivMod[S, R], S] other) -> R
+
+ # An interface for defining the `divmod` method. Used in `Integer#divmod`
+  interface _DivMod[O, R]
+    def divmod: (O other) -> R
+  end
 
   # <!--
   #   rdoc-file=numeric.c
@@ -876,7 +885,7 @@ class Float < Numeric
   # Related: Float#ceil.
   #
   def floor: () -> Integer
-           | (int digits) -> (Integer | Numeric)
+           | (int ndigits) -> (Integer | Float)
 
   # <!--
   #   rdoc-file=numeric.c
@@ -1043,12 +1052,12 @@ class Float < Numeric
   #
   # See also Float#denominator.
   #
-  def numerator: () -> Integer
+  def numerator: () -> (Integer | Float)
 
   # <!-- rdoc-file=complex.c -->
   # Returns 0 if `self` is positive, Math::PI otherwise.
   #
-  alias phase angle
+  alias phase arg
 
   def polar: () -> [ Float, Integer | Float ]
 
@@ -1108,8 +1117,8 @@ class Float < Numeric
   #     f.quo(Rational(2, 1)) # => 1.57
   #     f.quo(Complex(2, 0))  # => (1.57+0.0i)
   #
-  def quo: (Complex) -> Complex
-         | (Numeric) -> Float
+  def quo: (Integer | Float other) -> Float
+         | [S, R] (Numeric::_Coerce[self, RBS::Ops::_Divide[S, R], S] other) -> R
 
   # <!--
   #   rdoc-file=rational.c
@@ -1125,7 +1134,7 @@ class Float < Numeric
   #
   # See also Float#to_r.
   #
-  def rationalize: (?Numeric eps) -> Rational
+  def rationalize: (?Numeric eps) -> Rational # NB: `rationalize` has a bug in its logic, so `Numeric` is the safe choice
 
   def rect: () -> [ Float, Numeric ]
 
@@ -1305,7 +1314,7 @@ class Float < Numeric
   # Related: Float#round.
   #
   def truncate: () -> Integer
-              | (Integer ndigits) -> (Integer | Float)
+              | (int ndigits) -> (Integer | Float)
 
   # <!--
   #   rdoc-file=numeric.rb
diff --git a/core/numeric.rbs b/core/numeric.rbs
index fe6f800cda..cfa450c0b5 100644
--- a/core/numeric.rbs
+++ b/core/numeric.rbs
@@ -158,6 +158,14 @@
 class Numeric
   include Comparable
 
+ # The direction you can round
+  type round_mode = :up | :down | :even | 'up' | 'down' | 'even' | string | nil
+
+  # An interface that indicates a type can be coerced.
+  interface _Coerce[O, Other, Self]
+    def coerce: (O other) -> [Other, Self]
+  end
+
   # <!--
   #   rdoc-file=numeric.c
   #   - self % other -> real_numeric
diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index 6d23b95808..3a932559f2 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -90,23 +90,88 @@ def with_floats(infinity: true, nan: true)
   end
 
   def test_op_mod(method: :%)
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, method, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, method, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, method, 12.0
+      # no `Complex` as it doesnt have `%`
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, method, Coercable.for_op(:%) # Note: `.for_op(:%)` is correct
+    end
   end
 
   def test_op_mul
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, :*, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, :*, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, :*, 12.0
+      assert_send_type  '(Complex) -> Complex',
+                        float, :*, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :*, Coercable.for_op(:*)
+    end
   end
 
   def test_op_pow
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, :**, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, :**, 12r
+      assert_send_type  '(Rational) -> (Float | Complex)',
+                        float, :**, 1/2r
+      assert_send_type  '(Float) -> Float',
+                        float, :**, 12.0
+      assert_send_type  '(Float) -> (Float | Complex)',
+                        float, :**, 0.5
+      assert_send_type  '(Complex) -> Complex',
+                        float, :**, 0i
+      assert_send_type  '(Complex) -> Complex',
+                        float, :**, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :**, Coercable.for_op(:**)
+    end
   end
 
   def test_op_add
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, :+, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, :+, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, :+, 12.0
+      assert_send_type  '(Complex) -> Complex',
+                        float, :+, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :+, Coercable.for_op(:+)
+    end
   end
 
   def test_op_sub
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, :-, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, :-, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, :-, 12.0
+      assert_send_type  '(Complex) -> Complex',
+                        float, :-, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :-, Coercable.for_op(:-)
+    end
   end
 
   def test_op_uneg
@@ -117,19 +182,63 @@ def test_op_uneg
   end
 
   def test_op_div
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, :/, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, :/, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, :/, 12.0
+      assert_send_type  '(Complex) -> Complex',
+                        float, :/, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :/, Coercable.for_op(:/)
+    end
   end
 
   def test_op_lth
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> bool',
+                        float, :<, 12
+      assert_send_type  '(Rational) -> bool',
+                        float, :<, 12r
+      assert_send_type  '(Float) -> bool',
+                        float, :<, 12.0
+      # Notably not `Complex` as complex doesn't define `<`
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :<, Coercable.for_op(:<)
+    end
   end
 
   def test_op_leq
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> bool',
+                        float, :<=, 12
+      assert_send_type  '(Rational) -> bool',
+                        float, :<=, 12r
+      assert_send_type  '(Float) -> bool',
+                        float, :<=, 12.0
+      # Notably not `Complex` as complex doesn't define `<=`
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :<=, Coercable.for_op(:<=)
+    end
   end
 
   def test_op_cmp
-    omit 'todo'
+    with_floats do |float|
+      with_floats do |float2|
+        assert_send_type  '(Float) -> (-1 | 0 | 1)?',
+                          float, :<=>, float2
+      end
+
+      with_untyped.and float do |other|
+        assert_send_type  '(untyped) -> Integer?',
+                          float, :<=>, other
+      end
+    end
   end
 
   def test_op_eq(method: :==)
@@ -147,11 +256,33 @@ def test_op_eqq
   end
 
   def test_op_gth
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> bool',
+                        float, :>, 12
+      assert_send_type  '(Rational) -> bool',
+                        float, :>, 12r
+      assert_send_type  '(Float) -> bool',
+                        float, :>, 12.0
+      # Notably not `Complex` as complex doesn't define `>`
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :>, Coercable.for_op(:>)
+    end
   end
 
   def test_op_geq
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '(Integer) -> bool',
+                        float, :>=, 12
+      assert_send_type  '(Rational) -> bool',
+                        float, :>=, 12r
+      assert_send_type  '(Float) -> bool',
+                        float, :>=, 12.0
+      # Notably not `Complex` as complex doesn't define `>=`
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, :>=, Coercable.for_op(:>=)
+    end
   end
 
   def test_abs(method: :abs)
@@ -162,15 +293,26 @@ def test_abs(method: :abs)
   end
 
   def test_angle
-    omit 'todo'
+    test_arg(method: :angle)
   end
 
-  def test_arg
-    omit 'todo'
+  def test_arg(method: :arg)
+    with_floats do |float|
+      assert_send_type  '() -> (0 | Float)',
+                        float, method
+    end
   end
 
   def test_ceil
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Integer',
+                        float, :ceil
+
+      with_int(-1).and with_int(1) do |ndigits|
+        assert_send_type  '(int) -> (Float | Integer)',
+                          float, :ceil, ndigits
+      end
+    end
   end
 
   def test_coerce
@@ -183,11 +325,23 @@ def test_coerce
   end
 
   def test_denominator
-    omit 'todo'
+    with_floats do |float|
+      assert_send_type  '() -> Integer',
+                        float, :denominator
+    end
   end
 
   def test_divmod
-    omit 'todo'
+    assert_send_type  '(Integer) -> [Integer, Float]',
+                      38.0, :divmod, 12
+    assert_send_type  '(Rational) -> [Integer, Float]',
+                      38.0, :divmod, 12r
+    assert_send_type  '(Float) -> [Integer, Float]',
+                      38.0, :divmod, 12.0
+    # Notably not `Complex` as complex doesn't define `divmod`
+
+    assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                      38.0, :divmod, Coercable.for_op(:divmod)
   end
 
   def test_eql?
@@ -211,7 +365,15 @@ def test_finite?
   end
 
   def test_floor
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Integer',
+                        float, :floor
+
+      with_int(-1).and with_int(1) do |ndigits|
+        assert_send_type  '(int) -> (Float | Integer)',
+                          float, :floor, ndigits
+      end
+    end
   end
 
   def test_hash
@@ -262,11 +424,19 @@ def test_next_float
   end
 
   def test_numerator
-    omit 'todo'
+    with_floats do |float|
+      if float.nan? || float.infinite?
+        assert_send_type  '() -> Float',
+                          float, :numerator
+      else
+        assert_send_type  '() -> Integer',
+                          float, :numerator
+      end
+    end
   end
 
   def test_phase
-    omit 'todo'
+    test_arg(method: :phase)
   end
 
   def test_positive?
@@ -284,11 +454,33 @@ def test_prev_float
   end
 
   def test_quo(method: :quo)
-    omit 'todo'
+    # note: `quo` (and `fdiv`) actually is just a thin wrapper around `/`.
+    with_floats do |float|
+      assert_send_type  '(Integer) -> Float',
+                        float, method, 12
+      assert_send_type  '(Rational) -> Float',
+                        float, method, 12r
+      assert_send_type  '(Float) -> Float',
+                        float, method, 12.0
+      assert_send_type  '(Complex) -> Complex',
+                        float, method, 12i
+
+      assert_send_type  '(Coercable) -> Coercable::OpReturn',
+                        float, method, Coercable.for_op(:/)
+    end
   end
 
   def test_rationalize
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '(Integer) -> Rational',
+                        float, :rationalize, 1
+      assert_send_type  '(Rational) -> Rational',
+                        float, :rationalize, 1r
+      assert_send_type  '(Float) -> Rational',
+                        float, :rationalize, 1.2
+      assert_send_type  '(Complex) -> Rational',
+                        float, :rationalize, 1i
+    end
   end
 
   def test_round
@@ -314,7 +506,10 @@ def test_to_int
   end
 
   def test_to_r
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Rational',
+                        float, :to_r
+    end
   end
 
   def test_to_s(method: :to_s)
@@ -325,7 +520,15 @@ def test_to_s(method: :to_s)
   end
 
   def test_truncate
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Integer',
+                        float, :truncate
+
+      with_int(-1).and with_int(1) do |ndigits|
+        assert_send_type  '(int) -> (Float | Integer)',
+                          float, :truncate, ndigits
+      end
+    end
   end
 
   def test_zero?
diff --git a/test/stdlib/test_helper.rb b/test/stdlib/test_helper.rb
index b11939079d..4e09efc365 100644
--- a/test/stdlib/test_helper.rb
+++ b/test/stdlib/test_helper.rb
@@ -71,6 +71,43 @@ def with_timeout(seconds: 1, nanoseconds: 0)
   end
 end
 
+class Coercable < RBS::UnitTest::Convertibles::BlankSlate
+  class OpReturn < ::RBS::UnitTest::Convertibles::BlankSlate
+  end
+
+  class CoerceOther < ::RBS::UnitTest::Convertibles::BlankSlate
+    attr_reader :__value__
+    def initialize(value) = @__value__ = value
+  end
+
+  class CoerceSelf < ::RBS::UnitTest::Convertibles::BlankSlate
+    def initialize(method, &block)
+      ::Kernel.instance_method(:define_singleton_method).bind_call(self, method, &block)
+    end
+  end
+
+  def self.for_op(method, result: noresult = true, &block)
+    if block_given?
+      unless noresult
+        raise ArgumentError, "cannot provide both a block and a result"
+      end
+    else
+      block = proc { |other| noresult ? OpReturn.new : result }
+    end
+
+    new(CoerceSelf.new(method, &block)) { |x| CoerceOther.new(x) }
+  end
+
+  def initialize(self_ret, &converter)
+    @self_ret = self_ret
+    @converter = converter || ->(x) { x }
+  end
+
+  def coerce(rhs)
+    [@self_ret, @converter.(rhs)]
+  end
+end
+
 class Writer
   attr_reader :buffer
 

From 3ce0204b475ed8f9b3c9a3474252e1a7252d245d Mon Sep 17 00:00:00 2001
From: SamW <mail@sampersand.me>
Date: Wed, 17 Jun 2026 14:09:25 -0700
Subject: [PATCH 6/6] finished off float!

---
 core/float.rbs             |  4 ++--
 test/stdlib/Float_test.rb  | 20 +++++++++++++++++++-
 test/stdlib/test_helper.rb |  9 +++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/core/float.rbs b/core/float.rbs
index 28c54b3fd7..a6e0acfcbd 100644
--- a/core/float.rbs
+++ b/core/float.rbs
@@ -1193,8 +1193,8 @@ class Float < Numeric
   #
   # Related: Float#truncate.
   #
-  def round: (?half: :up | :down | :even) -> Integer
-           | (int digits, ?half: :up | :down | :even) -> (Integer | Float)
+  def round: (?half: Numeric::round_mode) -> Integer
+           | (int digits, ?half: Numeric::round_mode) -> (Integer | Float)
 
   # <!--
   #   rdoc-file=numeric.rb
diff --git a/test/stdlib/Float_test.rb b/test/stdlib/Float_test.rb
index 3a932559f2..b1a8ca3ed5 100644
--- a/test/stdlib/Float_test.rb
+++ b/test/stdlib/Float_test.rb
@@ -484,7 +484,25 @@ def test_rationalize
   end
 
   def test_round
-    omit 'todo'
+    with_floats infinity: false, nan: false do |float|
+      assert_send_type  '() -> Integer',
+                        float, :round
+
+      with_round_mode do |mode|
+        assert_send_type  '(half: Numeric::round_mode) -> Integer',
+                          float, :round, half: mode
+      end
+
+      with_int(-1).and with_int(1) do |digits|
+        assert_send_type  '(int) -> (Integer | Float)',
+                          float, :round, digits
+
+        with_round_mode do |mode|
+          assert_send_type  '(int, half: Numeric::round_mode) -> (Integer | Float)',
+                            float, :round, digits, half: mode
+        end
+      end
+    end
   end
 
   def test_to_f
diff --git a/test/stdlib/test_helper.rb b/test/stdlib/test_helper.rb
index 4e09efc365..30eab1952b 100644
--- a/test/stdlib/test_helper.rb
+++ b/test/stdlib/test_helper.rb
@@ -41,6 +41,15 @@ def if_ruby(range, skip: true)
 end
 
 module WithStdlibAliases
+  def with_round_mode(&block)
+    block.call(nil)
+
+    %i[up down even].each do |mode|
+      block.call(mode)
+      with_string(mode.to_s, &block)
+    end
+  end
+
   def with_timeout(seconds: 1, nanoseconds: 0)
     unless block_given?
       return RBS::UnitTest::WithAliases::WithEnum.new(