feat: add Failure equivalents

lib/typed/result.rb

@@ -151,6 +151,15 @@ def self.Success(payload)
     Success.new(payload)
   end
 
+  sig do
+    type_parameters(:T)
+      .params(error: T.type_parameter(:T))
+      .returns(Typed::Failure[T.type_parameter(:T)])
+  end
+  def self.Failure(error)
+    Failure.new(error)
+  end
+
   class Failure < Result
     extend T::Sig
     extend T::Generic
@@ -225,5 +234,10 @@ def on_error(&block)
     def payload_or(value)
       value
     end
+
+    sig { params(other: T.untyped).returns(T::Boolean) }
+    def ==(other)
+      other.is_a?(Failure) && other.error == error
+    end
   end
 end

test/test_data/failure.out

@@ -19,8 +19,8 @@ test/test_data/failure.rb:26: Expected `Integer` but found `String("error")` for
     26 |    Typed::Failure[Integer].new("error")
                                         ^^^^^^^
   Expected `Integer` for argument `error` of method `Typed::Failure#initialize`:
-    ./lib/typed/result.rb:178:
-     178 |    sig { params(error: Error).void }
+    ./lib/typed/result.rb:187:
+     187 |    sig { params(error: Error).void }
                            ^^^^^
   Got `String("error")` originating from:
     test/test_data/failure.rb:26:

test/typed/failure_test.rb

@@ -15,6 +15,10 @@ def test_blank_is_convenience_for_nil_error
     assert_nil failure.error
   end
 
+  def test_Failure_convenience_method
+    assert_equal @failure, Typed::Failure("Something bad")
+  end
+
   def test_it_is_failure
     assert_predicate @failure, :failure?
     assert_predicate @failure_without_error, :failure?
@@ -50,4 +54,10 @@ def test_on_error_calls_block_with_error_and_returns_self
   def test_payload_or_returns_value
     assert_equal(2, @failure.payload_or(2))
   end
+
+  def test_equals_works
+    assert_equal(@failure, Typed::Failure.new("Something bad"))
+    refute_equal(@failure, Typed::Failure.blank)
+    refute_equal(@failure, Typed::Success.new("Something bad"))
+  end
 end

test/typed/success_test.rb

@@ -16,7 +16,7 @@ def test_blank_is_convenience_for_nil_payload
   end
 
   def test_Success_convenience_method
-    assert_equal Typed::Success.new("Testing"), Typed::Success("Testing")
+    assert_equal @success, Typed::Success("Testing")
   end
 
   def test_it_is_success
@@ -55,6 +55,6 @@ def test_payload_or_returns_payload
   def test_equals_works
     assert_equal(@success, Typed::Success.new("Testing"))
     refute_equal(@success, Typed::Success.blank)
-    refute_equal(@success, Typed::Failure.blank)
+    refute_equal(@success, Typed::Failure.new("Testing"))
   end
 end