Merge pull request #38 from jturkel/add-argument-with-default

Adding non-null arguments with a default value should be non-breaking

Author: swalkinshaw

lib/graphql/schema_comparator/changes.rb

@@ -579,8 +579,8 @@ class InputFieldAdded < AbstractChange
         attr_reader :input_object_type, :field, :criticality
 
         def initialize(input_object_type, field)
-          @criticality = if field.type.non_null?
-            Changes::Criticality.breaking(reason: "Adding a non-null field to an existing input type will cause existing queries that use this input type to error because they will not provide a value for this new field.")
+          @criticality = if field.type.non_null? && !field.default_value?
+            Changes::Criticality.breaking(reason: "Adding a non-null input field without a default value to an existing input type will cause existing queries that use this input type to error because they will not provide a value for this new field.")
           else
             Changes::Criticality.non_breaking
           end
@@ -602,8 +602,8 @@ class FieldArgumentAdded < AbstractChange
         attr_reader :type, :field, :argument, :criticality
 
         def initialize(type, field, argument)
-          @criticality = if argument.type.non_null?
-            Changes::Criticality.breaking(reason: "Adding a required argument to an existing field is a breaking change because it will cause existing uses of this field to error.")
+          @criticality = if argument.type.non_null? && !argument.default_value?
+            Changes::Criticality.breaking(reason: "Adding a required argument without a default value to an existing field is a breaking change because it will cause existing uses of this field to error.")
           else
             Changes::Criticality.non_breaking
           end

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

@@ -0,0 +1,59 @@
+require "test_helper"
+
+class GraphQL::SchemaComparator::Changes::FieldArgumentAddedTest < Minitest::Test
+  def setup
+    @type = GraphQL::ObjectType.define do
+      name "Type"
+    end
+
+    @field = GraphQL::Field.define do
+      name "field"
+    end
+
+    @nullable_argument = GraphQL::Argument.define do
+      name "foo"
+      type GraphQL::STRING_TYPE
+    end
+
+    @non_null_argument = GraphQL::Argument.define do
+      name "foo"
+      type !GraphQL::STRING_TYPE
+    end
+
+    @non_null_argument_with_default = GraphQL::Argument.define do
+      name "foo"
+      type !GraphQL::STRING_TYPE
+      default_value "bar"
+    end
+  end
+
+  def test_nullable_added
+    change = GraphQL::SchemaComparator::Changes::FieldArgumentAdded.new(
+      @type,
+      @field,
+      @nullable_argument
+    )
+
+    assert change.non_breaking?
+  end
+
+  def test_non_null_added
+    change = GraphQL::SchemaComparator::Changes::FieldArgumentAdded.new(
+      @type,
+      @field,
+      @non_null_argument
+    )
+
+    assert change.breaking?
+  end
+
+  def test_non_null_with_default_added
+    change = GraphQL::SchemaComparator::Changes::FieldArgumentAdded.new(
+      @type,
+      @field,
+      @non_null_argument_with_default
+    )
+
+    assert change.non_breaking?
+  end
+end

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

@@ -0,0 +1,52 @@
+require "test_helper"
+
+class GraphQL::SchemaComparator::Changes::InputFieldAddedTest < Minitest::Test
+  def setup
+    @input_type = GraphQL::InputObjectType.define do
+      name "Input"
+    end
+
+    @nullable_input_field = GraphQL::Argument.define do
+      name "foo"
+      type GraphQL::STRING_TYPE
+    end
+
+    @non_null_input_field = GraphQL::Argument.define do
+      name "foo"
+      type !GraphQL::STRING_TYPE
+    end
+
+    @non_null_input_field_with_default = GraphQL::Argument.define do
+      name "foo"
+      type !GraphQL::STRING_TYPE
+      default_value "bar"
+    end
+  end
+
+  def test_nullable_added
+    change = GraphQL::SchemaComparator::Changes::InputFieldAdded.new(
+      @input_type,
+      @nullable_input_field
+    )
+
+    assert change.non_breaking?
+  end
+
+  def test_non_null_added
+    change = GraphQL::SchemaComparator::Changes::InputFieldAdded.new(
+      @input_type,
+      @non_null_input_field
+    )
+
+    assert change.breaking?
+  end
+
+  def test_non_null_with_default_added
+    change = GraphQL::SchemaComparator::Changes::InputFieldAdded.new(
+      @input_type,
+      @non_null_input_field_with_default
+    )
+
+    assert change.non_breaking?
+  end
+end