Fix field argument removed message

lib/graphql/schema_comparator/changes.rb

@@ -169,7 +169,7 @@ def initialize(object_type, field, argument)
         end
 
         def message
-          "Argument `#{argument.graphql_name}: #{argument.type.graphql_name}` was removed from field `#{object_type.graphql_name}.#{field.graphql_name}`"
+          "Argument `#{argument.graphql_name}: #{argument.type.to_type_signature}` was removed from field `#{object_type.graphql_name}.#{field.graphql_name}`"
         end
 
         def path

test/lib/graphql/schema_comparator/changes/field_argument_removed_test.rb

@@ -0,0 +1,35 @@
+require "test_helper"
+
+class GraphQL::SchemaComparator::Changes::FieldArgumentRemovedTest < Minitest::Test
+  class Type < GraphQL::Schema::Object
+    graphql_name "Type"
+
+    field :field, String, null: true do
+      argument :nullable, String, required: false
+      argument :non_null, String, required: true
+      argument :non_null_with_default, String, required: true, default_value: "bar"
+    end
+  end
+
+  def test_nullable_removed
+    change = GraphQL::SchemaComparator::Changes::FieldArgumentRemoved.new(
+      Type,
+      Type.fields["field"],
+      Type.fields["field"].arguments["nullable"],
+    )
+
+    assert change.breaking?
+    assert_equal change.message, "Argument `nullable: String` was removed from field `Type.field`"
+  end
+
+  def test_non_null_removed
+    change = GraphQL::SchemaComparator::Changes::FieldArgumentRemoved.new(
+      Type,
+      Type.fields["field"],
+      Type.fields["field"].arguments["nonNull"],
+    )
+
+    assert change.breaking?
+    assert_equal change.message, "Argument `nonNull: String!` was removed from field `Type.field`"
+  end
+end