feat: Add clearer message for CoercionNotSupportedError (#113)

lib/typed/coercion.rb

@@ -11,11 +11,11 @@ def self.register_coercer(coercer)
 
     sig { type_parameters(:U).params(type: T::Types::Base, value: Value).returns(Result[Value, CoercionError]) }
     def self.coerce(type:, value:)
-      coercer = CoercerRegistry.instance.select_coercer_by(type: type)
+      coercer = CoercerRegistry.instance.select_coercer_by(type:)
 
-      return Failure.new(CoercionNotSupportedError.new) unless coercer
+      return Failure.new(CoercionNotSupportedError.new(type:)) unless coercer
 
-      coercer.new.coerce(type: type, value: value)
+      coercer.new.coerce(type:, value:)
     end
   end
 end

lib/typed/coercion/coercion_not_supported_error.rb

@@ -2,6 +2,13 @@
 
 module Typed
   module Coercion
-    class CoercionNotSupportedError < CoercionError; end
+    class CoercionNotSupportedError < CoercionError
+      extend T::Sig
+
+      sig { params(type: T::Types::Base).void }
+      def initialize(type:)
+        super("Coercer not found for type #{type}.")
+      end
+    end
   end
 end

test/typed/coercion/coercion_not_supported_error_test.rb

@@ -0,0 +1,11 @@
+# typed: true
+
+require "test_helper"
+
+class CoercionNotSupportedErrorTest < Minitest::Test
+  def test_formats_message
+    error = Typed::Coercion::CoercionNotSupportedError.new(type: T::Utils.coerce(RubyRank))
+
+    assert_equal("Coercer not found for type RubyRank.", error.message)
+  end
+end

test/typed/coercion_test.rb

@@ -24,6 +24,6 @@ def test_when_coercer_isnt_matched_coerce_returns_failure
     result = Typed::Coercion.coerce(type: T::Utils.coerce(BigDecimal), value: "testing")
 
     assert_failure(result)
-    assert_error(Typed::Coercion::CoercionNotSupportedError.new, result)
+    assert_error(Typed::Coercion::CoercionNotSupportedError.new(type: T::Utils.coerce(BigDecimal)), result)
   end
 end